JP2018182524A - Semiconductor device, battery monitoring system, activation signal detection method, and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent or reduce the occurrence of harmful effects due to noise entering a communication line in communication between semiconductor devices performed via a communication line.SOLUTION: An activation detection circuit includes: a first input terminal and a second input terminal connected with a first communication line; a rectification unit provided between the first and second terminals for generating current if potential of the first input terminal is higher than potential of the second input terminal; a voltage generation unit for generating voltage if the current is generated; and an output unit for outputting a detection signal in response to generation of the voltage.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a semiconductor device, a battery monitoring system, a detection method of a start signal, and a communication method.

  A battery monitoring system is known that monitors the state of each of a plurality of battery cells that configure a battery pack using a plurality of battery monitoring semiconductor devices connected in a communicable manner.

  For example, Patent Document 1 includes monitoring means for monitoring the battery voltage of a battery cell group, voltage generation means for generating a driving voltage from the battery voltage of the battery cell group, communication means operating with the driving voltage, and power saving mode. A battery monitoring system is described which comprises a plurality of battery monitoring devices each provided with control means for controlling the driving of the voltage generating means according to the setting signal. In this battery monitoring system, when the power saving mode setting signal is output, in one of the battery monitoring devices that received it, the control means activates the voltage generation means to bring it into a driving state, and supplies the supply voltage according to the drive voltage. Supply to the other battery monitoring device. In the other battery monitoring device to which the supply voltage is supplied, the control means activates the voltage generation means to bring it into a driving state.

JP 2014-134454 A

  In a battery monitoring system configured such that a plurality of battery monitoring semiconductor devices (hereinafter referred to as battery monitoring ICs) are communicatively connected in multiple stages, each of the battery monitoring ICs is operated from a stop state (power-down state) When starting up, the controller that controls the plurality of battery monitoring ICs transmits a start signal to the battery monitoring IC of the first stage.

  Each of the battery monitoring ICs is provided with a start detection circuit for detecting a start signal, and the battery monitoring IC at the first stage transitions to the active state when it detects the start signal supplied from the controller in its own start detection circuit. The start signal is transmitted to the battery monitoring IC of the stage. The battery monitoring IC of the next stage transitions to the active state when it detects the startup signal supplied from the battery monitoring IC of the first stage in its startup detection circuit. The supply of the start signal from the battery monitoring IC of the first stage to the battery monitoring IC of the next stage is performed via a communication line for performing communication between these battery monitoring ICs. Noise may be mixed into the communication line, and the noise mixed into the communication line may erroneously detect the start signal in the start detection circuit of the battery monitoring IC of the next stage.

  Each of the battery monitoring ICs includes a communication circuit connected to the communication line, and transmits and receives various data between the battery monitoring ICs. Communication between the battery monitoring ICs may be performed using a differential signal to eliminate the influence of common mode noise mixed in the communication line. For example, when a power supply voltage not containing noise is applied to the communication circuit of the battery monitoring IC of the next stage that communicates with the communication circuit of the battery monitoring IC of the first stage, the battery monitoring IC of the first stage via the communication line Consider the case where noise is mixed in the communication signal supplied from the. When the amplitude of the noise mixed in the communication signal exceeds the voltage width of the power supply voltage applied to the communication circuit of the battery monitoring IC of the next stage, the reception signal received by the battery monitoring IC of the next stage has the voltage level of the power supply voltage. There is a risk that the communication signal supplied from the battery monitoring IC in the first stage can not be properly received by the battery monitoring IC in the next stage.

  The present invention has been made in view of the above-described points, and it is an object of the present invention to suppress the occurrence of adverse effects due to noise mixed in a communication line in communication between semiconductor devices performed via the communication line. .

  A semiconductor device according to the present invention includes a start detection circuit that outputs a detection signal when a start signal supplied via a pair of first communication lines forming a differential transmission line is detected; A first power supply circuit and a second power supply circuit activated respectively when the detection signal is output, and a first communication line connected to the first power supply circuit, the power supply voltage supplied from the first power supply circuit A second communication circuit for transmitting the start signal to a pair of second communication lines constituting a differential transmission line when the first communication circuit and the second power supply circuit receive the supply voltage from the second power supply circuit and start up; And a circuit. The activation detection circuit is provided between a first input terminal and a second input terminal connected to the first communication line, and the first terminal and the second terminal, A rectifying unit that generates a current when the potential of the input terminal of the input terminal is higher than the potential of the second input terminal, a voltage generating unit that generates a voltage when the current is generated, and the generation of the voltage And an output unit that outputs the detection signal.

  A battery monitoring system according to the present invention is a battery monitoring system including a first semiconductor device and a second semiconductor device for monitoring the state of each of a plurality of battery cells connected in series. Each of the first semiconductor device and the second semiconductor device is activated to output a detection signal when the activation signal supplied through the pair of first communication lines constituting the differential transmission line is detected. A detection circuit, a first power supply circuit and a second power supply circuit activated respectively when the detection signal is output from the activation detection circuit, and the first communication line, the first power supply being connected A first communication circuit receiving supply of a power supply voltage from the circuit, and a pair of second communication circuits forming the differential transmission line when the start is received by receiving the supply of the power supply voltage from the second power supply circuit; The power supply voltage is supplied from the second communication circuit to be sent to the communication line and the power supply circuit activated when the detection signal is output, and the voltage of the corresponding battery cell among the plurality of battery cells is measured. Cell voltage measurement circuit . The second communication circuit of the first semiconductor device and the first communication circuit of the second semiconductor device are connected via a communication line. The activation detection circuit is provided between a first input terminal and a second input terminal connected to the first communication line, and the first terminal and the second terminal, A rectifying unit that generates a current when the potential of the input terminal of the input terminal is higher than the potential of the second input terminal, a voltage generating unit that generates a voltage when the current is generated, and the generation of the voltage And an output unit that outputs the detection signal.

  In the method of detecting a start signal according to the present invention, when a start signal supplied via a pair of communication lines constituting a differential transmission line is detected, detection of the start signal in a start detection circuit which outputs a detection signal In the method, when the potential of the first input terminal among the first input terminal and the second input terminal connected to the communication line is higher than the potential of the second input terminal, Generating the current, and outputting the detection signal based on the voltage generated as the current is generated, without generating the current when the potential of the first input terminal is lower than the potential of the second input terminal. Including.

  Another semiconductor device according to the present invention receives a supply of a voltage from a battery cell and outputs a first power supply voltage, and a supply of the first power supply voltage, and externally receives a differential signal. A first communication circuit for communicating with the second power supply circuit, and a second power supply circuit receiving supply of voltage from the battery cell and outputting a second power supply voltage having a voltage level different from that of the first power supply voltage And a second communication circuit that receives the supply of the second power supply voltage and communicates with the outside by a differential signal.

  Another communication system according to the present invention is a battery monitoring system including a first semiconductor device and a second semiconductor device that monitors the state of each of a plurality of battery cells connected in series. Each of the first semiconductor device and the second semiconductor device receives a supply of voltage from a battery cell and outputs a first power supply voltage, and a supply of the first power supply voltage. Receiving, supplying a voltage from the battery cell to a first communication circuit that communicates with the outside by a differential signal, and outputting a second power supply voltage having a voltage level different from the voltage level of the first power supply voltage And a second communication circuit that receives supply of the second power supply voltage and communicates with the outside by a differential signal, and a voltage of a corresponding battery cell among the plurality of battery cells. And a cell voltage measurement circuit to be measured. The second communication circuit of the first semiconductor device and the first communication circuit of the second semiconductor device are connected via a pair of communication lines that form a differential transmission line.

  A communication method according to the present invention includes a communication circuit provided in a first semiconductor device including a cell voltage measurement circuit that measures a voltage of a battery cell on the high potential side among a plurality of battery cells connected in series; And a communication circuit provided in a second semiconductor device including a cell voltage measurement circuit for measuring a voltage of a battery cell on the low potential side among the battery cells, the battery on the high potential side A power supply circuit that supplies a voltage output from a power supply circuit that receives a supply of voltage from a cell as a power supply voltage of a communication circuit provided in the first semiconductor device, and receives a supply of a voltage from the low potential battery cell Supplying the voltage output from the circuit as a power supply voltage of a communication circuit provided in the second semiconductor device.

  According to the present invention, in communication between semiconductor devices performed via a communication line, it is possible to suppress the occurrence of adverse effects due to noise mixed in the communication line.

It is a circuit block diagram showing composition of a battery surveillance system concerning an embodiment of the present invention. It is a circuit diagram showing an example of composition of a starting detection circuit concerning an embodiment of the present invention. It is a timing chart which shows operation at the time of starting of a battery monitoring system concerning an embodiment of the present invention. It is a timing chart which shows the voltage of each part at the time of starting of the battery monitoring system concerning the embodiment of the present invention in the case where noise is not generated in the connection line of a battery cell. It is a timing chart which shows the voltage of each part at the time of starting of the battery monitoring system concerning the embodiment of the present invention in the case where noise is generated in the connection line of a battery cell. FIG. 7 is a circuit diagram showing a configuration of a start detection circuit according to a comparative example. It is a timing chart which shows the voltage of each part at the time of starting of the battery monitoring system using the starting detection circuit concerning a comparative example. It is a timing chart which shows the voltage of each part at the time of starting of the battery monitoring system using the starting detection circuit concerning a comparative example. It is a timing chart which shows the voltage of each part of battery monitoring IC at the time of the signal transmission from battery monitoring IC of the first step to battery monitoring IC of the next step, when noise is not generated in the connection line of a battery cell. It is a timing chart which shows the voltage of each part of battery monitoring IC at the time of the signal transmission from battery monitoring IC of the first step to battery monitoring IC of the next step, when noise is not generated in the connection line of a battery cell. It is a timing chart which shows the voltage of each part of battery monitoring IC at the time of the signal transmission from battery monitoring IC of the first step to battery monitoring IC of the next step, when noise is generated in the connection line of a battery cell. It is a timing chart which shows the voltage of each part of battery monitoring IC at the time of the signal transmission from battery monitoring IC of the first step to battery monitoring IC of the next step, when noise is generated in the connection line of a battery cell. It is a circuit block diagram which shows the structure of the battery monitoring system provided with battery monitoring IC which concerns on a comparative example. In the battery monitoring system according to the comparative example, the voltage of each portion of the battery monitoring IC at the time of signal transmission from the battery monitoring IC of the first stage to the battery monitoring IC of the next stage when noise is generated in the connection line of the battery cell Is a timing chart showing In the battery monitoring system according to the comparative example, the voltage of each portion of the battery monitoring IC at the time of signal transmission from the battery monitoring IC of the first stage to the battery monitoring IC of the next stage when noise is generated in the connection line of the battery cell Is a timing chart showing

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, substantially the same or equivalent components or parts are denoted by the same reference numerals.

  FIG. 1 is a circuit block diagram showing a configuration of a battery monitoring system 1 according to an embodiment of the present invention. Battery monitoring system 1 is a system for monitoring the state of each battery cell 50 of a battery pack including a plurality of battery cells 50 connected in series.

  Battery monitoring system 1 communicably connects battery monitoring ICs 10_1 and 10_2 connected in cascade, an MCU (Micro Controller Unit) 22 for controlling battery monitoring ICs 10_1 and 10_2, MCU 22 and battery monitoring IC 10_1, and electrically connects them. And an assembled battery including a plurality of battery cells 50. In the present embodiment, a battery monitoring system having a two-stage battery monitoring IC is illustrated as an example, but the number of stages of the battery monitoring IC is appropriately changed according to the number of battery cells to be monitored. It is possible.

  The plurality of battery cells 50 are grouped to include a plurality of different battery cells, forming battery cell groups 51A, 51B. The battery monitoring IC 10_1 is provided corresponding to the battery cell group 51A on the high potential side, and monitors the state of each of the battery cells 50 included in the battery cell group 51A. Battery monitoring IC 10_2 is provided corresponding to battery cell group 51B, and monitors the state of each of battery cells 50 included in battery cell group 51B. The number of battery cells 50 monitored by each of the battery monitoring ICs 10_1 and 10_2 can be changed as appropriate.

  The battery monitoring ICs 10_1 and 10_2 are semiconductor devices each including an integrated circuit (IC: Integrated Circuit) formed on a semiconductor substrate. The battery monitoring ICs 10_1 and 10_2 have the same configuration, and respectively have the booster circuit 11, the step-down circuit 12, the cell voltage measurement circuit 13, the start detection circuit 14, the regulator 15, the control circuit 16, and the first communication circuit 17. , And the second communication circuit 18 and the switch circuit 19.

  The cell voltage measurement circuit 13 is connected to each electrode of each battery cell 50 constituting the corresponding battery cell group, and measures the cell voltage of each battery cell 50.

  The low-pass filter 20 removes noise components from the positive electrodes of the battery cells on the highest potential side of the battery cell groups 51A and 51B. The booster circuit 11 outputs a voltage VUP (> VCC) obtained by boosting the voltage VCC from which the noise component output from the low pass filter 20 is removed. The voltage VUP output from the booster circuit 11 is supplied to the cell voltage measurement circuit 13.

  The step-down circuit 12 is directly connected to the positive electrode of the battery cell 50 on the highest potential side in the corresponding battery cell group, and outputs a voltage VCC2 (<VCC1) obtained by reducing the voltage VCC1 of the positive electrode of the battery cell.

  The negative electrode of the battery cell 50 on the lowest potential side in the corresponding battery cell group is connected to the low potential side power supply input terminal of the regulator 15, and the voltage VSS of the negative electrode of the battery cell 50 is input. The output terminal of the low pass filter 20 is connected to the power supply input terminal on the high potential side of the regulator 15, and the output voltage VCC of the low pass filter 20 is input. The regulator 15 outputs a voltage VDD (<VCC2) having a predetermined voltage level.

  The first communication circuit 17 is supplied with the voltage VCC1 of the positive electrode of the battery cell 50 on the highest potential side in the corresponding battery cell group and the voltage VCC2 output from the step-down circuit 12 as a power supply voltage. The first communication circuit 17 of the battery monitoring IC 10_1 is connected to the insulating circuit 24 via the pair of communication lines L1 and L2. The communication lines L1 and L2 constitute a differential transmission line, and transmit differential signals whose signal levels are complementary to each other. That is, the first communication circuit 17 communicates with the MCU 22 using differential signals through the communication lines L1 and L2.

  The second communication circuit 18 is supplied with the voltage VSS of the negative electrode of the battery cell 50 on the lowest potential side in the corresponding battery cell group and the voltage VDD output from the regulator 15 as a power supply voltage. The second communication circuit 18 of the battery monitoring IC 10_1 is connected to the first communication circuit 17 of the battery monitoring IC 10_2 via the pair of communication lines L3 and L4. The communication lines L3 and L4 constitute a differential transmission line, and transmit differential signals whose signal levels are complementary to each other. That is, the second communication circuit 18 of the battery monitoring IC 10_1 and the first communication circuit 17 of the battery monitoring IC 10_2 communicate with each other using differential signals through the communication lines L3 and L4. Capacitors C1 and C2 for blocking a DC component are provided in the middle of the communication line L3 and in the middle of the communication line L4, respectively.

  The control circuit 16 controls the first communication circuit 17, the second communication circuit 18 and the cell voltage measurement circuit 13.

  The start detection circuit 14 of the battery monitoring IC 10_1 is connected to the communication lines L1 and L2 via the switch circuit 19. The start detection circuit 14 of the battery monitoring IC 10_1 outputs a detection signal Sd when it detects a start signal supplied from the MCU 22 via the communication lines L1 and L2 when the battery monitoring IC 10_1 is in the stop state (power down state). . The detection signal Sd output from the start detection circuit 14 of the battery monitoring IC 10_1 is supplied to the booster circuit 11, the step-down circuit 12, and the regulator 15 of the battery monitoring IC 10_1. The booster circuit 11, the step-down circuit 12, and the regulator 15 of the battery monitoring IC 10_1 in the stopped state are activated when the detection signal Sd is supplied, and respectively output the voltages VUP, VCC2, and VDD.

  The start detection circuit 14 of the battery monitoring IC 10_2 is connected to the communication lines L3 and L4 via the switch circuit 19 circuit. When battery monitoring IC 10_2 is in the stopped state (power-down state), start-up detection circuit 14 of battery monitoring IC 10_2 is connected to communication lines L3 and L4 from second communication circuit 18 of battery monitoring IC 10_1 that has been activated first. When a start signal supplied via the circuit is detected, the detection signal Sd is output. The detection signal Sd output from the start detection circuit 14 of the battery monitoring IC 10_2 is supplied to the booster circuit 11, the step-down circuit 12, and the regulator 15 of the battery monitoring IC 10_2. The booster circuit 11, the step-down circuit 12, and the regulator 15 of the battery monitoring IC 10_2 in the stopped state are activated when the detection signal Sd is supplied, and respectively output the voltages VUP, VCC2, and VDD.

  FIG. 2 is a circuit diagram showing an example of the configuration of the start detection circuit 14 according to the embodiment of the present invention. The start detection circuit 14 has an input terminal T1 connected to the communication line L1 (or L4) via the switch circuit 19 and an input terminal T2 connected to the communication line L2 (or L3) via the switch circuit 19. The input terminals T1 and T2 are connected to the VCC line to which the voltage VCC is supplied via the resistance elements R1 and R2, respectively, and are pulled up to the voltage VCC.

  The start-up detection circuit 14 includes a rectifying unit 31 including a resistor element R3 and a diode D1 provided between the input terminals T1 and T2. One end of the resistive element R3 is connected to the input terminal T1, and the other end is connected to the anode of the diode D1. The cathode of the diode D1 is connected to the input terminal T2.

  The start detection circuit 14 has a voltage generation unit 32 that generates a voltage when a current is generated in the rectification unit 31. The voltage generation unit 32 includes a p-channel type transistor M1, a resistance element R4, and inverters A1 and A2. The gate of the transistor M1 is connected to the connection point of the resistive element R3 and the diode D1, the source is connected to the input terminal T1, and the drain is connected to one end of the resistive element R4. The other end of the resistive element R4 is connected to the VSS line to which the voltage VSS is supplied. The input end of the inverter A1 is connected to the connection point of the transistor M1 and the resistance element R4, and the output end is connected to the input end of the inverter A2.

  The start detection circuit 14 has a latch circuit La that functions as an output unit 33 that outputs a detection signal Sd in accordance with the generation of a voltage in the voltage generation unit 32. The input end of the latch circuit La is connected to the output end of the inverter A2.

  The operation at the time of start of the battery monitoring system 1 will be described below. FIG. 3 is a timing chart showing an operation at the time of startup of the battery monitoring system 1.

  When the battery monitoring ICs 10_1 and 10_2 are in the stopped state (power down state), in the battery monitoring ICs 10_1 and 10_2, the booster circuit 11, the step-down circuit 12 and the regulator 15 are off and the voltages VCC1, VCC2 and VDD are generated. Absent. That is, in the battery monitoring ICs 10_1 and 10_2, since the power supply voltage is not supplied to the first communication circuit 17, the second communication circuit 18 and the control circuit 16, these circuits are in the stop state. When the battery monitoring ICs 10_1 and 10_2 are in the stop state, the switch of the switch circuit 19 is turned on, and the start detection circuit 14 can receive the start signal.

  When the start signal is output from the MCU 22, the start signal is converted into a differential signal type signal in the isolation circuit 24. The activation signal converted into the differential signal format is input to the battery monitoring IC 10_1 of the first stage via the communication lines L1 and L2, and is input to the activation detection circuit 14 of the battery monitoring IC 10_1 via the switch circuit 19. When the start-up detection circuit 14 of the battery monitoring IC 10_1 in the first stage detects a start-up signal, it outputs a detection signal Sd and supplies it to the voltage booster circuit 11, the step-down circuit 12 and the regulator 15 of the battery monitoring IC 10_1. The booster circuit 11, the step-down circuit 12 and the regulator 15 of the battery monitoring IC 10_1 are activated when the detection signal Sd is supplied, and respectively output voltages VUP, VCC1 and VCC2, VDD. As a result, the cell voltage measurement circuit 13, the control circuit 16, the first communication circuit 17 and the second communication circuit 18 of the battery monitoring IC 10_1 receive supply of the power supply voltage, and these circuits are activated to monitor the battery. The IC 10_1 is in operation.

  The second communication circuit 18 of the battery monitoring IC 10_1 in the first stage, which has been activated, outputs a start signal in the form of a differential signal and supplies it to the battery monitoring IC 10_2 in the next stage via the communication lines L3 and L4. Here, start signals of the differential signal format transmitted from the battery monitoring IC 10_1 of the first stage are TX and TXN, and start signals of the differential signal format received by the battery monitoring IC 10_2 of the next stage are RX and RXN. The start-up detection circuit 14 of the battery monitoring IC 10_2 at the next stage outputs a detection signal Sd when detecting the start-up signal. As a result, the cell voltage measurement circuit 13, the control circuit 16, the first communication circuit 17 and the second communication circuit 18 of the battery monitoring IC 10_2 in the next stage are activated, and the battery monitoring IC 10_2 is in an operating state.

  Noise may occur in a connection line in which a plurality of battery cells 50 constituting a battery pack are connected in series. Therefore, noise is also superimposed on the voltage VSS at the connection point of the battery cell group 51A and the battery cell group 51B. In the battery monitoring IC 10_1, noise is also superimposed on the voltage VDD output from the regulator 15 to which the voltage VSS is supplied. Furthermore, noise is also superimposed on the communication lines L3 (TX, RX) and L4 (TXN, RXN) connected to the second communication circuit 18 to which the voltage VSS and the voltage VDD are supplied as the power supply voltage. The noise superimposed on the communication lines L3 (TX, RX) and L4 (TXN, RXN) is in-phase noise.

  FIG. 4A is a timing chart showing voltages of the respective parts at the time of startup of the battery monitoring system 1 when noise is not generated in the connection line of the battery cell 50. FIG. 4B is a timing chart showing the voltage of each part at the time of startup of the battery monitoring system 1 when noise is generated in the connection line of the battery cell 50.

  According to the start detection circuit 14 according to the embodiment of the present invention, the battery monitoring IC 10_1 in the first stage to the battery monitoring IC 10_2 in the next stage via the communication lines L3 and L4 due to the noise generated in the connection line of the battery cell 50. Even when noise is superimposed on the supplied start signal (TX, TXN, RX, RXN), the start detection circuit 14 of the battery monitoring IC 10_2 at the next stage is appropriate as in the case where noise is not generated (see FIG. 4A) The detection signal Sd can be output at proper timing. That is, according to the start detection circuit 14 according to the embodiment of the present invention, it is possible to prevent erroneous detection of the start signal even when noise is generated in the communication line through which the start signal is transmitted.

  The operation of the start detection circuit 14 will be described below. When the input terminals T1 and T2 of the start-up detection circuit 14 are at the same potential, the diode D1 maintains the off state, and the rectifying unit 31 configured of the resistor element R3 and the diode D1 does not generate a current. Therefore, since the transistor M1 maintains the off state, the input end of the inverter A1 and the output end of the inverter A2 maintain the low level. Thus, the signal level of the detection signal Sd output from the latch circuit La maintains a low level indicating that the start signal is not detected. The same applies to the case where the potential of the input terminal T2 is higher than the potential of the input terminal T1.

  On the other hand, the start signal is input to the input terminals T1 and T2 of the start detection circuit 14, the potential of the input terminal T1 becomes higher than the potential of the input terminal T2, and the potential difference between the input terminals T1 and T2 is the order of the diode D1. When it becomes larger than the directional voltage VF, the diode D1 is turned on, and the rectifying unit 31 configured by the resistance element R3 and the diode D1 generates a current. This current causes a potential difference between both ends of the resistance element R3, and the transistor M1 is turned on. When the transistor M1 is turned on, a current flows through the resistance element R4, a high level voltage is input to the input end of the inverter A1, and a high level voltage is generated at the output end of the inverter A2. As a result, the signal level of the detection signal Sd output from the latch circuit La changes to the high level indicating that the start signal has been detected. When the signal level of the detection signal Sd is changed to the high level, the latch circuit La maintains the signal level of the detection signal Sd at the high level while the battery monitoring IC is in the operating state.

  As described above, according to the start detection circuit 14 according to the present embodiment, when the potential of the input terminal T1 becomes higher than the potential of the input terminal T2, the signal level of the detection signal Sd detects that the start signal is detected. The signal level of the detection signal Sd is low when transitioning to the high level shown, the potential of the input terminal T1 and the potential of the input terminal T2 are the same, and the potential of the input terminal T2 becomes higher than the potential of the input terminal T1. Maintain the level. Therefore, even if the in-phase noise is superimposed on the start signals (TX, TXN, RX, RXN) supplied from the battery monitoring IC 10_1 of the first stage to the battery monitoring IC 10_2 of the next stage via the communication lines L3 and L4, the battery of the next stage The start detection circuit 14 of the monitoring IC 10_2 can appropriately detect the start signal.

  FIG. 5 is a circuit diagram showing a configuration of the start detection circuit 14X according to the comparative example. The start detection circuit 14X includes input terminals T11 and T12, n-channel transistors M11 and M12, p-channel transistors M13 and M14, an inverter A11, a latch circuit La, and resistance elements R11, R12, R13, R14, and R15. It consists of

  Activation signals are input to the input terminals T11 and T12 through communication lines, respectively. One end of the resistive element R11 is connected to the input terminal T11, and the other end is connected to the VSS line. One end of the resistive element R12 is connected to the input terminal T12, and the other end is connected to the voltage VSS line. That is, the input terminals T11 and T12 are pulled down.

  The transistor M11 has a gate connected to the input terminal T11, a source connected to the VSS line, and a drain connected to the drain of the transistor M13 and the gate of the transistor M14. The transistor M12 has a gate connected to the input terminal T12, a source connected to the VSS line, and a drain connected to the drain of the transistor M14 and the gate of the transistor M13.

  The sources of the transistors M13 and M14 are connected to the VCC line via the resistors R13 and R14, respectively. The input end of the inverter A11 is connected to the drain of the transistor M12, and is connected to the VCC line via the resistor element R15, and the output end is connected to the input end of the latch circuit La.

  In the start detection circuit 14X according to the comparative example, when the start signal at high level to the input terminal T12 and low level to the input terminal T11 is input, the input end of the inverter A11 becomes low level and the output end becomes high level, and the latch The signal level of the detection signal Sd output from the output end of the circuit La becomes a high level indicating that the start signal has been detected.

  FIGS. 6A and 6B are timing charts showing voltages of respective portions at the start of the battery monitoring system using the start detection circuit 14X according to the comparative example instead of the start detection circuit 14 according to the embodiment of the present invention, FIG. 6A shows the case where noise is not generated in the connection line of the battery cell 50, and FIG. 6B shows the case where noise is generated in the connection line of the battery cell 50.

  As shown in FIG. 6A, when noise is not generated in the connection line of the battery cell 50, the start detection circuit 14X according to the comparative example uses the start signal (RX, RXN) received from the battery monitoring IC 10_1 in the first stage. Based on this, the signal level of the detection signal Sd is transitioned to the high level at an appropriate timing.

  On the other hand, as shown in FIG. 6B, in the battery monitoring IC 10_2, even when noise is generated in the connection line of the battery cell 50, the voltage VSS and the voltage VCC applied as the power supply voltage of the start detection circuit 14X are Noise is not superimposed. In the battery monitoring IC 10 _ 2, the voltage VSS is fixed to the ground voltage (GND), and the voltage VCC is an output signal of the low pass filter 20. On the other hand, the noise superimposed on the communication lines L3 and L4 is applied to the input terminals T11 and T12 of the start detection circuit 14X of the battery monitoring IC 10_2. In such a situation, the transistors M11 and M12 whose gates are connected to the input terminals T11 and T12 are turned on and off by the noise applied to the input terminals T11 and T12, and the parasitic capacitance Cp1 of the drain of the transistor M11 and the transistor M12 are When the parasitic capacitance Cp2 of the drain is different (Cp1 <Cp2), the voltage level of the drain of the transistor M12 oscillates between the high level and the low level, and thereby the detection signal Sd output from the latch circuit La The level may transition to the high level and be held. That is, when noise is superimposed on the communication lines L3 and L4, the start detection circuit 14X of the battery monitoring IC 10_2 in the next stage may erroneously detect the start signal.

  On the other hand, according to the start detection circuit 14 according to the embodiment of the present invention, as described above, the diode D1 maintains the off state even when the common phase noise is applied to the input terminals T1 and T2. Since the high level voltage is not applied to the input terminal, the signal level of the detection signal Sd is prevented from transitioning to the high level due to the in-phase noise superimposed on the communication line.

  Next, an operation in the case where each of the battery monitoring ICs 10_1 and 10_2 measures the voltage of the battery cell 50 and transmits the measurement result to the MCU 22 will be described.

  First, the MCU 22 outputs a command to measure the voltage of the battery cell 50 to the battery monitoring ICs 10_1 and 10_2. This command is received by the first communication circuit 17 of the battery monitoring IC 10 _ 1 of the first stage via the insulating circuit 24. The first communication circuit 17 of the battery monitoring IC 10_1 transmits the received command to the control circuit 16. The control circuit 16 causes the cell voltage measurement circuit 13 to measure the cell voltage of the battery cell 50 based on the command from the MCU 22. The control circuit 16 also transmits a command from the MCU 22 to the second communication circuit 18. The second communication circuit 18 transmits a command from the MCU 22 to the battery monitoring IC 10_2 at the next stage via the communication lines L3 and L4.

  The command from the MCU 22 transmitted from the battery monitoring IC 10_1 of the first stage is received by the first communication circuit 17 of the battery monitoring IC 10_2 of the next stage. The first communication circuit 17 of the battery monitoring IC 10_2 transmits the received command to the control circuit 16. The control circuit 16 causes the cell voltage measurement circuit 13 to measure the cell voltage of the battery cell 50 based on the command from the MCU 22.

  The measurement result of the cell voltage measured by the cell voltage measurement circuit 13 of the battery monitoring IC 10 _ 2 of the next stage is transmitted to the first communication circuit 17 via the control circuit 16. The first communication circuit 17 of the next-stage battery monitoring IC 10_2 transmits the measurement result of the cell voltage to the second communication circuit 18 of the first-stage battery monitoring IC 10_1 via the communication lines L3 and L4.

  The second communication circuit 18 of the first-stage battery monitoring IC 10_1 transmits the measurement result of the cell voltage received from the next-stage battery monitoring IC 10_2 to the control circuit 16. The control circuit 16 transmits the measurement result of the cell voltage received from the battery monitoring IC 10 _ 2 of the next stage to the first communication circuit 17. Thereafter, the control circuit 16 transmits the measurement result of the cell voltage measured by the cell voltage measurement circuit 13 of the battery monitoring IC 10_1 to the first communication circuit 17. The first communication circuit 17 communicates the measurement result of the cell voltage measured by the cell voltage measurement circuit 13 of the battery monitoring IC 10_2 and the measurement result of the cell voltage measured by the cell voltage measurement circuit 13 of the battery monitoring IC 10_1 as a communication line. The data is sequentially transmitted to the MCU 22 through the L1, L2 and the isolation circuit 24.

  FIGS. 7A and 7B respectively show the cases of the battery monitoring ICs 10_1 and 10_2 at the time of signal transmission from the battery monitoring IC 10_1 of the first stage to the battery monitoring IC 10_2 of the next stage when noise is not generated in the connection line of the battery cell 50. It is a timing chart which shows the voltage of each part.

  In the second communication circuit 18 of the first-stage battery monitoring IC 10_1, the voltage VSS of the negative electrode of the battery cell on the lowest potential side in the battery cell group 51A corresponding to the battery monitoring IC 10_1 and the voltage VDD output from the regulator 15 are power supply voltages Supplied as Therefore, the high level in the differential signal type transmission signals TX and TXN transmitted from the first-stage battery monitoring IC 10_1 is the same level as the level Vdd of the voltage VDD, and the low level in the transmission signals TX and TXN is the level of the voltage VSS It becomes the same level as Vss.

  In the first communication circuit 17 of the battery monitoring IC 10_2 in the next stage, the voltage VCC1 of the positive electrode of the battery cell on the highest potential side in the battery cell group 51B corresponding to the battery monitoring IC 10_2 and the voltage VCC2 output from the step-down circuit 12 It is supplied as a power supply voltage. That is, the first communication circuit 17 of the battery monitoring IC 10_2 is directly connected to the connection line of the battery cell 50, and the voltage VCC1 not passing through the low pass filter 20 and the voltage VCC2 stepped down from the voltage VCC1 are the first power supply voltages. Is supplied to the communication circuit 17 of FIG. The first communication circuit 17 of the battery monitoring IC 10_2 in the next stage receives the transmission signals TX and TXN transmitted from the battery monitoring IC 10_1 in the first stage as reception signals RX and RXN. The high level of the reception signals RX and RXN is the same as the level Vcc1 of the voltage VCC1, and the low level of the reception signals RX and RXN is the same as the level Vcc2 of the voltage VCC2. Since the transmission signals TX and TXN and the reception signals RX and RXN become the same signal, communication becomes possible between the battery monitoring IC 10_1 of the first stage and the battery monitoring IC 10_2 of the next stage.

  8A and 8B show the respective parts of the battery monitoring ICs 10_1 and 10_2 at the time of signal transmission from the battery monitoring IC 10_1 of the first stage to the battery monitoring IC 10_2 of the next stage when noise is generated in the connection line of the battery cell 50. It is a timing chart which shows voltage.

  As shown in FIG. 8A, when noise is generated in the connection line of the battery cell 50, the noise is also superimposed on the voltage VDD and the voltage VSS, and the voltage VDD and the voltage VSS are supplied as the power supply voltage. The noise is also superimposed on the transmission signals TX and TXN transmitted from the communication circuit 18 and the reception signals RX and RXN received by the communication circuit 17 of the battery monitoring IC 10_2. The noise superimposed on the transmission signals TX and TXN and the reception signals RX and RXN transmitted to the communication lines L3 and L4 is in-phase noise.

  As shown in FIG. 8B, when noise is generated in the connection line of the battery cell 50, the noise is also superimposed on the voltages VCC1 and VCC2 supplied as the power supply voltage of the first communication circuit 17 of the battery monitoring IC 10_2 in the next stage. . The noise superimposed on the received signals RX and RXN received by the communication circuit 17 of the battery monitoring IC 10_2 in the next stage and the noise superimposed on the voltages VCC1 and VCC2 are in-phase noise, so the received signals RX and RXN have noise amplitudes of Even if it becomes large, it is not clamped at the level Vcc1 of the voltage VCC1 and the level Vcc2 of the voltage VCC2. Therefore, even if noise is superimposed on the transmission signals TX and TXN, in the first communication circuit 17 of the battery monitoring IC 10_2 in the next stage, the differential signal corresponding to the difference between TX and TXN is the difference between RX and RXN. It becomes possible to receive appropriately as a corresponding differential signal.

  FIG. 9 is a circuit block diagram showing a configuration of a battery monitoring system 1X provided with battery monitoring ICs 10_1X and 10_2X according to a comparative example. In the battery monitoring ICs 10_1X and 10_2X according to the comparative example, the voltage VCC output from the low pass filter 20 from which the noise component is removed and the voltage VUP (> VCC) not including the noise component output from the booster circuit 11 are power supply voltages. As different from the battery monitoring ICs 10_1 and 10_2 according to the embodiment of the present invention.

  In the second communication circuit 18 of the first-stage battery monitoring IC 10_1X, the voltage VSS of the negative electrode of the battery cell on the lowest potential side in the battery cell group 51A corresponding to the battery monitoring IC 10_1X and the voltage VDD output from the regulator 15 are power supply voltages Supplied as Therefore, when noise is not generated in the connection line of the battery cell 50, the high level in the transmission signals TX and TXN of the differential signal format transmitted from the battery monitoring IC 10_1X of the first stage is the same level as the level Vdd of the voltage VDD. The low level of the transmission signals TX and TXN is the same level as the level Vss of the voltage VSS.

  In the first communication circuit 17 of the battery monitoring IC 10_2X of the next stage, the voltage VCC from which the noise component output from the low-pass filter 20 is removed and the voltage VUP not including the noise component output from the booster circuit 11 are used as power supply voltages. Supplied. The first communication circuit 17 of the battery monitoring IC 10_2X of the next stage receives the transmission signals TX and TXN transmitted from the battery monitoring IC 10_1X of the first stage as reception signals RX and RXN. When noise is not generated in the connection line of the battery cell 50, the high level in the reception signal RX, RXN is the same level as the level Vup of the voltage VUP, and the low level in the reception signal RX, RXN is the voltage VCC. It becomes the same level as the level Vcc. When noise is not generated in the connection line of the battery cell 50, the transmission signals TX and TXN and the reception signals RX and RXN become the same signal, so the second communication circuit 18 of the first stage battery monitoring IC 10_1X and the second stage Communication is possible with the first communication circuit 17 of the battery monitoring IC 10_2X. As described above, in the battery monitoring ICs 10_1X and 10_2X according to the comparative example, the first communication circuit 17 is supplied with the power supply voltage not including the noise component, while the second communication circuit 18 receives the noise component. Power supply voltage is supplied.

  In the battery monitoring system 1X according to the comparative example, when noise is generated in the connection line of the battery cell 50 in FIGS. 10A and 10B, at the time of signal transmission from the battery monitoring IC 10_1X of the first stage to the battery monitoring IC 10_2X of the next stage. These are timing charts showing the voltages of the respective units of the battery monitoring ICs 10_1X and 10_2X.

  As shown in FIG. 10A, when noise is generated in the connection line of the battery cell 50, the noise is also superimposed on the voltage VDD and the voltage VSS, and the voltage VDD and the voltage VSS are supplied as the power supply voltage. Noise is also superimposed on the transmission signals TX and TXN transmitted from the communication circuit 18 of FIG.

  On the other hand, as shown in FIG. 10B, even when noise is generated in the connection line of battery cell 50, voltage VUP and voltage VCC supplied as the power supply voltage of first communication circuit 17 of battery monitoring IC 10_2X of the next stage are Noise is not superimposed. In such a situation, when the amplitude of the noise increases, the reception signals RX and RXN received by the first communication circuit 17 of the battery monitoring IC 10_2X of the next stage are the first as shown in FIG. 10B. It is clamped at the level Vcc of the voltage VCC which is the power supply voltage of the communication circuit 17 and the level Vup of the voltage VUP. In this case, in the differential signal corresponding to the difference between the reception signal RX and RXN, an indefinite region Z indicated by hatching in FIG. 10B is generated, and the signal transmitted from the second communication circuit 18 of the battery monitoring IC 10_1X is The first communication circuit 17 of the monitoring IC 10_2X can not receive properly.

  As described above, in the battery monitoring system 1X according to the comparative example, the voltage VSS and voltage VDD with noise superimposed are supplied as the power supply voltage to the second communication circuit 18 of the battery monitoring IC 10_1X of the first stage, and the battery of the next stage The first communication circuit 17 of the monitoring IC 10_2X is supplied with the voltage VCC and the voltage VUP not superimposed with noise as a power supply voltage. As a result, when the noise amplitude increases, the reception signals RX and RXN are clamped at the levels Vcc and Vup of the power supply voltage supplied to the first communication circuit 17 of the battery monitoring IC 10_2X, and the battery monitoring IC 10_1X Communication with the battery monitoring IC 10_2X may become impossible.

  On the other hand, according to the battery monitoring system 1 according to the embodiment of the present invention, the second communication circuit 18 of the battery monitoring IC 10_1 of the first stage and the first communication circuit 17 of the battery monitoring IC 10_2 of the next stage mutually have the same noise. Since the power supply voltage including is applied, the reception signals RX and RXN received by the first communication circuit 17 of the battery monitoring IC 10 _ 2 of the next stage are concerned even when the noise amplitude increases. Communication between the second communication circuit 18 of the battery monitoring IC 10_1 and the first communication circuit 17 of the battery monitoring IC 10_2 without clamping at the voltage level of the power supply voltage supplied to the first communication circuit 17 Can be kept good.

  In the above description, the case where the first communication circuit 17 of the battery monitoring IC 10_2 of the next stage receives the signal transmitted from the second communication circuit 18 of the battery monitoring IC 10_1 of the first stage has been described. In the case where the second communication circuit 18 of the battery monitoring IC 10_1 of the first stage receives the signal transmitted from the first communication circuit 17 of the battery monitoring IC 10_2, the same effect can be obtained.

  Further, in the present embodiment, the case where the voltage VCC2 output from the step-down circuit 12 is supplied as the power supply voltage of the first communication circuit 17 has been exemplified. It may be supplied as a power supply voltage. In this case, a voltage not passing through the low pass filter 20 is input to the booster circuit so that noise in phase with noise generated in the connection line of the battery cell 50 is superimposed on the voltage output from the booster circuit.

  The battery monitoring system 1 is an example of the battery monitoring system in the present invention. The battery monitoring ICs 10_1 and 10_2 are examples of the semiconductor device in the present invention. The start detection circuit 14 is an example of the start detection circuit in the present invention. The step-down circuit 12 is an example of the first power supply circuit in the present invention. The regulator 15 is an example of a second power supply circuit in the present invention. The first communication circuit 17 is an example of the first communication circuit in the present invention. The second communication circuit 18 is an example of the second communication circuit in the present invention.

1 Battery monitoring system 10_1, 10_2 Battery monitoring IC
11 step-up circuit 12 step-down circuit 13 cell voltage measurement circuit 14 activation detection circuit 15 regulator 16 control circuit 17 first communication circuit 18 first communication circuit 19 second communication circuit 19 switch circuit 20 low pass filter 31 rectification unit 32 voltage generation unit 33 output unit 50 battery Cell L1, L2, L3, L4 Communication line R1, R2, R3, R4 Resistance element A1, A2 Inverter D1 Diode M1 Transistor La Latch circuit T1, T2 Input terminal

Claims (11)

A start detection circuit which outputs a detection signal when a start signal supplied via a pair of first communication lines constituting a differential transmission line is detected;
A first power supply circuit and a second power supply circuit that are activated when the detection signal is output from the activation detection circuit;
A first communication circuit connected to the first communication line and receiving supply of a power supply voltage from the first power supply circuit;
A second communication circuit for sending out the start signal to a pair of second communication lines constituting a differential transmission line when it is started by receiving supply of a power supply voltage from the second power supply circuit;
Including
The start detection circuit is
A first input terminal and a second input terminal connected to the first communication line;
A rectifying unit provided between the first input terminal and the second input terminal and generating a current when the potential of the first input terminal is higher than the potential of the second input terminal;
A voltage generation unit that generates a voltage when the current is generated;
An output unit that outputs the detection signal according to the generation of the voltage;
Semiconductor devices. The rectifying unit includes a first resistance element and a diode connected to the first resistance element.
The voltage generation unit includes a transistor whose gate is connected to a connection point between the first resistance element and the diode, and a second resistance element connected to the transistor.
The semiconductor device according to claim 1, wherein the output unit includes a latch circuit that holds a signal level of the detection signal. The semiconductor device according to claim 1, further comprising a cell voltage measurement circuit that receives supply of a power supply voltage from a power supply circuit activated when the detection signal is output, and measures a voltage of a battery cell. The semiconductor device according to claim 3, wherein the first power supply circuit and the second power supply circuit each receive supply of a voltage from the battery cell. What is claimed is: 1. A battery monitoring system including a first semiconductor device and a second semiconductor device for monitoring the state of each of a plurality of battery cells connected in series, comprising:
The first semiconductor device and the second semiconductor device are respectively
A start detection circuit which outputs a detection signal when a start signal supplied via a pair of first communication lines constituting a differential transmission line is detected;
A first power supply circuit and a second power supply circuit that are activated when the detection signal is output from the activation detection circuit;
A first communication circuit connected to the first communication line and receiving supply of a power supply voltage from the first power supply circuit;
A second communication circuit for sending out the start signal to a pair of second communication lines constituting a differential transmission line when it is started by receiving supply of a power supply voltage from the second power supply circuit;
A cell voltage measurement circuit receiving supply of a power supply voltage from a power supply circuit activated when the detection signal is output, and measuring a voltage of a corresponding battery cell among the plurality of battery cells;
Including
The second communication circuit of the first semiconductor device and the first communication circuit of the second semiconductor device are connected via a communication line,
The start detection circuit is
A first input terminal and a second input terminal connected to the first communication line;
A rectifying unit provided between the first input terminal and the second input terminal and generating a current when the potential of the first input terminal is higher than the potential of the second input terminal;
A voltage generation unit that generates a voltage when the current is generated;
An output unit that outputs the detection signal according to the generation of the voltage;
Battery monitoring system including: A method for detecting the activation signal in an activation detection circuit which outputs a detection signal when detecting an activation signal supplied through a pair of communication lines constituting a differential transmission line,
A current is generated when the potential of the first input terminal among the first input terminal and the second input terminal connected to the communication line is higher than the potential of the second input terminal; A detection method for outputting the detection signal based on a voltage generated along with the generation of the current without generating the current when the potential of the input terminal of 1 is lower than the potential of the second input terminal. A first power supply circuit receiving voltage supply from the battery cell and outputting a first power supply voltage;
A first communication circuit that receives supply of the first power supply voltage and communicates with the outside by a differential signal;
A second power supply circuit receiving voltage supply from the battery cell and outputting a second power supply voltage having a voltage level different from that of the first power supply voltage;
A second communication circuit that receives supply of the second power supply voltage and communicates with the outside by a differential signal;
Semiconductor devices. The semiconductor device according to claim 7, wherein the first power supply circuit includes a step-down circuit that steps down a terminal voltage of the battery cell. The semiconductor device according to claim 7, further comprising a cell voltage measurement circuit that measures a voltage of the battery cell. What is claimed is: 1. A battery monitoring system including a first semiconductor device and a second semiconductor device for monitoring the state of each of a plurality of battery cells connected in series, comprising:
The first semiconductor device and the second semiconductor device are respectively
A first power supply circuit receiving voltage supply from the battery cell and outputting a first power supply voltage;
A first communication circuit that receives supply of the first power supply voltage and communicates with the outside by a differential signal;
A second power supply circuit receiving voltage supply from the battery cell and outputting a second power supply voltage having a voltage level different from that of the first power supply voltage;
A second communication circuit that receives supply of the second power supply voltage and communicates with the outside by a differential signal;
A cell voltage measurement circuit that measures a voltage of a corresponding battery cell among the plurality of battery cells;
Including
The second communication circuit of the first semiconductor device and the first communication circuit of the second semiconductor device are connected through a pair of communication lines that form a differential transmission line. system. Among the plurality of battery cells connected in series, the communication circuit provided in the first semiconductor device including the cell voltage measurement circuit for measuring the voltage of the battery cell on the high potential side, and the low one of the plurality of battery cells A communication method with a communication circuit provided in a second semiconductor device including a cell voltage measurement circuit for measuring a voltage of a battery cell on a potential side,
Supplying a voltage output from a power supply circuit receiving supply of voltage from the battery cell on the high potential side as a power supply voltage of a communication circuit provided in the first semiconductor device;
A communication method comprising: supplying a voltage output from a power supply circuit that receives supply of voltage from a battery cell on the low potential side as a power supply voltage of a communication circuit provided in the second semiconductor device.