JP2009075957A - Power circuit and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power circuit and a semiconductor device mounted with the power circuit capable of high accuracy detection with low loss of electric power even under high voltage. <P>SOLUTION: The power circuit has a main power supply 3 for supplying a load current; a main transistor 4 for adjusting the load current; a sense transistor 5 similar in characteristics to the main transistor 4; and a current detecting resistance 9 connected to the sense transistor 5. An auxiliary power supply 10 included in a current detecting circuit 2 connected to the reference potential of the main power supply 3 included in a main circuit 1 is used to supply a required current to the sense transistor 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power supply device for controlling a direct current, for example, a power supply circuit including a current detection circuit for detecting a current when a large current flows from a direct current high-voltage power supply to a load, and a semiconductor device equipped with the power supply circuit, Furthermore, the present invention relates to a technique effective when applied to a control circuit using the power supply circuit, a control device using the control circuit, and the like.

For example, there are many current detection circuit technologies, and the most frequently used method is a shunt resistance detection method. However, the shunt resistance detection method has a disadvantage that loss is large at a large current. For example, Japanese Patent Application Laid-Open No. H10-133707 discloses a method for detecting the current with high accuracy while suppressing this loss.
JP-A-6-180332

  By the way, in Patent Document 1, a current is supplied from a main power source, and a potential difference is generated between commonly connected terminals, so that highly accurate detection cannot be performed. Furthermore, when the main power source is at a high voltage, there remains a problem that a large power loss occurs.

  Accordingly, an object of the present invention is to provide a power supply circuit capable of realizing highly accurate detection and low power loss even at a high voltage, and a semiconductor device mounted with the power supply circuit.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  That is, a typical outline is that a main power source that supplies a load current, a main transistor that adjusts the load current, a sense transistor that has similar characteristics to the main transistor, and a power source that has a current detection resistor connected to the sense transistor The circuit is configured to supply a necessary current to the sense transistor by using an auxiliary power source included in the current detection circuit connected to a reference potential of the main power source included in the main circuit.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  That is, the effect obtained by the typical one is that current does not flow between the main circuit and the current detection circuit, and voltage drop due to parasitic impedance does not occur, so that detection accuracy can be improved. Furthermore, power loss can be suppressed much more than when a detection circuit is configured between a high potential and a ground potential. As a result, from the above two effects, it is possible to realize a power supply circuit with high accuracy detection and low power loss, a semiconductor device equipped with the power supply circuit, and the like.

(Outline of the embodiment of the present invention)
The embodiment of the present invention is configured such that in a power supply circuit, a necessary current is supplied to the sense transistor using an auxiliary power supply provided separately from the main power supply. For example, in order to measure the current of a path at a high potential, a potential that is several volts lower than the high potential is formed using a charge pump circuit or the like, and current detection is performed between the potentials.

  In particular, when detecting a current flowing through a transistor to which a high voltage is applied, a power supply circuit that can reduce power loss, maintain high detection accuracy, and achieve cost reduction, and a semiconductor device including the power supply circuit, Provides a control circuit using the power supply circuit, a control device using the control circuit, and the like.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

(Embodiment 1)
FIG. 1 shows an example of the configuration of a power supply circuit according to Embodiment 1 of the present invention.

  The power supply circuit according to the first embodiment includes a main circuit 1 and a current detection circuit 2.

  The main circuit 1 includes a main power supply 3, a main transistor 4, and a load 6. The main power supply 3 functions as a first power supply for supplying a load current, and the main transistor 4 functions as a first transistor for adjusting the load current.

  The current detection circuit 2 includes an auxiliary power supply 10, a sense transistor 5, a current detection operational amplifier 7, a transistor 8, and a current detection resistor 9. The auxiliary power supply 10 has one end connected to the reference potential side of the main power supply 3 and functions as a second power supply for supplying a current flowing through the sense transistor 5. The sense transistor 5 is a second transistor having characteristics similar to those of the main transistor 4. Function as.

  In the configuration of the main circuit 1 and the current detection circuit 2, the source terminals of the main transistor 4 and the sense transistor 5 are connected to each other, and the voltage applied to the drain terminal of the main transistor 4 and the drain terminal of the sense transistor 5 is controlled to be the same. A feedback loop is formed. The feedback loop for controlling the voltage equally is configured using the current detection operational amplifier 7.

  In the main circuit 1, the main power supply 3, the main transistor 4, and the load 6 are connected in series, and a current adjustment signal is input from the input terminal 11 to the gate terminal of the main transistor 4. That is, the positive terminal (reference potential) of the main power supply 3 is connected to the source terminal of the main transistor 4. The drain terminal of the main transistor 4 is connected to one terminal of the load 6. The other terminal of the load 6 and the negative terminal of the main power supply 3 are connected to the GND potential.

  In the current detection circuit 2, the main transistor 4 and the sense transistor 5 have a gate terminal and a source terminal connected in common. The drain terminal of the main transistor 4 is connected to one terminal of the load 6 and the non-inverting input terminal (+) of the current detection operational amplifier 7. The drain terminal of the sense transistor 5 is connected to the inverting input terminal (−) of the current detection operational amplifier 7 and the drain terminal of the transistor 8. The output of the current detection operational amplifier 7 is connected to the gate terminal of the transistor 8. The source terminal of the transistor 8 is connected to one terminal of the current detection resistor 9. The other terminal of the current detection resistor 9 is connected to the negative terminal of the auxiliary power supply 10. The positive terminals (reference potential) of the main power supply 3 and the auxiliary power supply 10 and the source terminals of the main transistor 4 and the sense transistor 5 are connected in common. The plus / minus power supply terminal of the current detection operational amplifier 7 is connected to the plus / minus terminal of the auxiliary power supply 10, and the drive current of the current detection operational amplifier 7 is supplied from the auxiliary power supply 10.

  The main transistor 4 and the sense transistor 5 have similar characteristics, are formed on the same semiconductor substrate, and the size of the sense transistor 5 (or the number of unit transistors, etc.) is 1 / N of the main transistor 4. When all the node potentials of the transistors 4 and 5 are equal, the on-resistance of the sense transistor 5 is N times the on-resistance of the main transistor 4, and a current 1 / N of the main transistor 4 flows through the sense transistor 5.

  In the power supply circuit of FIG. 1, the voltage output from the main power supply 3 is applied to both ends of the main transistor 4 and the load 6, and current is supplied to the load 6 according to the gate voltage state of the main transistor 4 and the state of the load 6. Since the source terminal and gate terminal of the main transistor 4 and the sense transistor 5 are commonly connected, and the current detection operational amplifier 7 forms a feedback loop, the drain voltages of the main transistor 4 and the sense transistor 5 are equal. . Since all terminal potentials of the main transistor 4 and the sense transistor 5 are equal, a current proportional to the current flowing through the main transistor 4 flows through the sense transistor 5 in accordance with the on-resistance ratio of the main transistor 4 and sense transistor 5. The current flowing through the sense transistor 5 flows through the transistor 8 and the current detection resistor 9, and the voltage across the current detection resistor 9 becomes the detection voltage. The auxiliary power supply 10 has a voltage smaller than that of the main power supply 3 and supplies a current that flows through the sense transistor 5, the transistor 8, and the current detection resistor 9 and a current that drives the current detection operational amplifier 7.

  As described above, in the current detection circuit 2 that accurately diverts the current flowing through the load 6 and the main transistor 4 to the sense transistor 5 and the current detection resistor 9 using the current detection operational amplifier 7, a voltage smaller than that of the main power supply 3 is used. The auxiliary power supply 10 is used to provide a slightly lower potential from the main power supply 3 to detect the current flowing through the main transistor 4 to which a high voltage is applied.

  If configured as in the first embodiment, the main circuit 1 and the current detection circuit 2 are individually set with current routes, and the influence of the parasitic impedance existing between the source terminals of the main transistor 4 and the sense transistor 5 is affected. Current detection is possible without receiving. As a result, a voltage drop due to parasitic impedance does not occur, which has an effect of improving detection accuracy. Furthermore, compared with the case where the circuit is configured without using the auxiliary power supply 10, the power loss is double the voltage of the auxiliary power supply 10 corresponding to the voltage of the main power supply 3, so that a significant loss reduction effect can be obtained.

  Although the current detection resistor 9 is arranged on the low side of the transistor 8 in the first embodiment, the current detection resistor 9 may be arranged on the high side of the transistor 8 or on the route of the current flowing through the sense transistor 5. If it is okay.

  In the first embodiment, the gate terminals of the main transistor 4 and the sense transistor 5 are connected in common. However, it is sufficient that an equal voltage is applied to the gate terminals of the main transistor 4 and the sense transistor 5 at a timing when current is desired to be detected.

  In the first embodiment, the main transistor 4 and the sense transistor 5 are P-type MOSFETs as an example. However, both the transistors 4 and 5 may be N-type MOSFETs or bipolar transistors. The same. Similarly, the transistor 8 can be configured by a P-type MOSFET, a bipolar transistor, a variable resistor, a voltage-current converter, and the like. For example, when each transistor is composed of an N-type MOSFET, the connection between the source terminal and the drain terminal is reversed, and when each transistor is composed of a bipolar transistor, the source terminal is an emitter terminal and a drain terminal. Replaces the collector terminal and the gate terminal to the base terminal.

  Furthermore, since the current detection operational amplifier 7 according to the first embodiment needs to form an accurate voltage feedback circuit, the circuit for reducing the offset voltage of the current detection operational amplifier 7 includes a capacitor and a switch. An offset cancel circuit may be incorporated in the current detection operational amplifier 7.

(Embodiment 2)
FIG. 2 shows an example of the configuration of the power supply circuit according to Embodiment 2 of the present invention.

  In the power supply circuit of the second embodiment, a control unit 20 is added in addition to the main circuit 1 and the current detection circuit 2 described in the first embodiment (FIG. 1).

  The control unit 20 includes a subtraction circuit 21 that converts a reference value of the detection voltage in the current detection resistor 9 to a ground potential, and a control circuit 22 that controls the power supply voltage of the main power supply 3.

  The subtraction circuit 21 includes an operational amplifier 23, a resistor 24, a resistor 25, a resistor 26, and a resistor 27. Each terminal of the current detection resistor 9 is connected to the non-inverting input terminal / inverting input terminal of the operational amplifier 23 through resistors 24 and 25. A resistor 26 having one terminal connected to the GND potential is connected to the non-inverting input terminal of the operational amplifier 23. A resistor 27 is connected between the inverting input terminal and the output terminal of the operational amplifier 23. The driving current for the operational amplifier 23 is supplied from the main power supply 3. At this time, the current route is designed not to pass between the source terminal of the main transistor 4 and the source terminal of the sense transistor 5. The subtraction circuit 21 inputs a voltage generated at both ends of the current detection resistor 9, and outputs a differential voltage as current information. As a result, the reference value of the detection voltage can be converted to the ground potential.

  The control circuit 22 includes an operational amplifier 28, a comparator 29, a reference voltage 30, a resistor 31, a resistor 32, a capacitor 33, a power source 34, a power source 35, and a triangular wave generator 36. The output of the subtraction circuit 21 is connected to the inverting input terminal of the operational amplifier 28 through the resistor 31. A reference voltage 30 is connected to the non-inverting input terminal of the operational amplifier 28. The output terminal of the operational amplifier 28 is connected to the non-inverting input terminal of the comparator 29. A triangular wave generator 36 is connected to the non-inverting input terminal of the comparator 29. A resistor 32 and a capacitor 33 are connected between the inverting input terminal and the output terminal of the operational amplifier 28. The driving current for the operational amplifier 28 is supplied from the power supply 34. The driving current for the comparator 29 is supplied from the power source 35. The current information output from the subtraction circuit 21 is input to the control circuit 22 and controls the main circuit 1 according to the current information. Here, when the main circuit 1 is controlled, the current information is converted into a PWM signal for driving the main power supply 3.

  By adopting the configuration of the second embodiment, in addition to the effects of the first embodiment, the reference value of the detection voltage generated at both ends of the current detection resistor 9 can be converted into the ground potential. It becomes possible to use it for control.

  In the second embodiment, the detected current information is converted into a PWM signal for driving the main power supply 3. However, the detected current information depends on the configuration of the control circuit 22 and the main circuit 1, and the detected current information is the gate voltage of the main transistor 4. It does not matter how it is used.

(Embodiment 3)
FIG. 3 shows an example of the configuration of the power supply circuit according to Embodiment 3 of the present invention.

  The power supply circuit according to the third embodiment is different from the second embodiment (FIG. 2) in the configuration of the subtracting circuit 21 and includes a voltage dividing resistor 40, a voltage dividing resistor 41, and a power source.

  In the subtraction circuit 21, the voltage dividing resistor 40 and the voltage dividing resistor 41 are connected in series. One terminal of the voltage dividing resistor 40 is connected to one terminal of the current detection resistor 9, and the voltage dividing resistor 40 and the voltage dividing resistor 41 are connected to each other. The connection node is connected to the resistor 24, and one terminal (GND potential) of the voltage dividing resistor 41 is connected to the resistor 25. In the subtraction circuit 21, the detection voltage generated at one end of the current detection resistor 9 is divided by the voltage dividing resistor 40 and the voltage dividing resistor 41 and is generated at one end of the voltage dividing resistor 41. The driving current for the operational amplifier 23 is supplied from a low voltage power source 42.

  By adopting the configuration of the third embodiment, in addition to the effects of the first embodiment, the drive voltage of the operational amplifier 23 can be lowered, and the low-voltage power source 42 for driving the control circuit 22 and the IC. Thus, the operational amplifier 23 can be driven. As a result, the loss generated in the operational amplifier 23 can be significantly reduced.

(Embodiment 4)
FIG. 4 shows an example of the configuration of a power supply circuit according to Embodiment 4 of the present invention.

  In the power supply circuit according to the fourth embodiment, the negative terminal of the auxiliary power supply 10 is set to the GND2 potential higher than the GND potential, and the subtracting circuit 21 and the control circuit 22 are operated at the GND2 potential. Furthermore, a voltage dividing resistor 50, a voltage dividing resistor 51, a reference voltage 52, a comparator 53, and a power source 54 are added to the control unit 20.

  The voltage dividing resistor 50 and the voltage dividing resistor 51 are connected in series, one terminal of the voltage dividing resistor 50 is connected to the output of the comparator 29, and the connection node between the voltage dividing resistor 40 and the voltage dividing resistor 41 is inverted by the comparator 53. One terminal of the voltage dividing resistor 51 is connected to the GND potential to the input terminal. A reference voltage 52 is connected to the non-inverting input terminal of the comparator 53. The drive current for the comparator 53 is supplied from the power supply 54. The voltage level of the PWM waveform output from the control circuit 22 is dropped by the voltage dividing resistor 50 and the voltage dividing resistor 51, and the voltage of the node to which the voltage dividing resistor 50 and the voltage dividing resistor 51 are connected and the reference voltage 52 are obtained by the comparator 53. The PWM waveform of the required voltage level is generated by comparison.

  If the configuration of the fourth embodiment is adopted, a part of the control circuit 22 operates based on the voltage at one end of the auxiliary power supply 10, and the GND2 potential is higher than the GND potential. It is possible to realize the drive voltage of the control circuits 23 and 28 and the comparator 29 with a low voltage, and to configure the control unit 20 with extremely low loss.

(Embodiment 5)
FIG. 5 shows an example of the configuration of a power supply circuit according to Embodiment 5 of the present invention.

  In the power supply circuit of the fifth embodiment, the main circuit 1 and the control circuit 22 of the second embodiment (FIG. 2) are the same, but the current detection circuit 2 and the subtraction circuit 21 are different. The current detection circuit 2 includes a transistor 60, a transistor 61, a transistor 62, a transistor 63, and a current detection resistor 64. The transistors 60 and 61, the transistors 62 and 63 constitute current mirror circuits, respectively, and the detection current flowing through the sense transistor 5 and the transistor 8 flows through the current detection resistor 64. In the subtracting circuit 21, the driving current for the operational amplifier 23 is supplied from a low voltage power source 42.

  The current detection circuit 2 is sensed in proportion to the current flowing through the load 6 by the first current mirror circuit composed of the transistor 60 and the transistor 61 and the second current mirror circuit composed of the transistor 62 and the transistor 63. The detection current flowing through the transistor 5 and the transistor 8 is supplied to the current detection resistor 64, and a detection voltage is obtained across the current detection resistor 64.

  In the fifth embodiment, since this configuration is adopted, a detection voltage proportional to the GND potential can be obtained as the voltage generated in the current detection resistor 64, so that the control unit 20 can be driven at a low voltage. Therefore, since the drive voltage of the subtraction circuit 21 can be driven at a low voltage, the low loss subtraction circuit 21 can be configured. Since the current detection circuit 2 is also applied with a high voltage only by the transistor 63, the loss is suppressed by adjusting the current values of the first current mirror circuit and the second current mirror circuit, and the other circuits of the current detection circuit 2 are controlled. Can operate at a low voltage, so that loss can be suppressed.

  The current mirror circuits of the fifth embodiment have different voltages applied to the left and right, so that a Wilson current mirror circuit may be used to detect an accurate current.

(Embodiment 6)
FIG. 6 shows an example of the configuration of a power supply circuit according to Embodiment 6 of the present invention.

  The power supply circuit according to the sixth embodiment is similar to the first embodiment (FIG. 1) in that a switch 71 for cutting off the current flowing through the current detection resistor 9 is used to protect the main transistor 4 and the sense transistor 5 when they are off. , A switch 72, a switch 73, and a switch 74 are added. The switch 71 and the switch 72 are synchronized with the main transistor 4 and the sense transistor 5, and the corresponding switches 72 and 71 are turned on when the transistors 4 and 5 are turned on, and are turned off when turned off. The switch 73 and the switch 74 are synchronized with a signal having a phase opposite to that of the main transistor 4 and the sense transistor 5. When the transistors 4 and 5 are turned on, the corresponding switches 74 and 73 are turned off. Turn on.

  In the sixth embodiment, the switch 71, the switch 72, the switch 73, and the switch 74 block the current flowing through the current detection resistor 9 when the main transistor 4 and the sense transistor 5 are in the OFF state, Has a configuration in which no current flows. Furthermore, there is an effect of determining the potential of an indeterminate node, which can contribute to the high-speed response of the current detection operational amplifier 7.

(Embodiment 7)
FIG. 7 shows an example of the configuration of a power supply circuit according to Embodiment 7 of the present invention.

  In the power supply circuit according to the seventh embodiment, the main circuit 1 is a circuit that supplies current from the main power supply 3 to the load 6 and performs on / off of the current and adjustment of the current value by the main transistor 4. The difference from the first embodiment (FIG. 1) is that the main transistor 4 is connected to the low side of the load 6. That is, the plus terminal of the main power supply 3 is connected to one terminal of the load 6. The other terminal of the load 6 is connected to the drain terminal of the main transistor 4. The source terminal of the main transistor 4 and the negative terminal of the main power supply 3 are connected to the GND potential.

  The current detection circuit 2 has a sense transistor 5 in which a main transistor 4 and a drain terminal are connected in common and a feedback loop is formed so that a source terminal has the same potential as the main transistor 4 using a current detection operational amplifier 7. The detection current proportional to the current flowing through the main transistor 4 is configured to flow through the current detection resistor 9. That is, the main transistor 4 and the sense transistor 5 commonly connect the gate terminal and the drain terminal. The source terminal of the main transistor 4 is connected to the plus terminal of the auxiliary power supply 10 and the non-inverting input terminal (+) of the current detection operational amplifier 7. The source terminal of the sense transistor 5 is connected to the inverting input terminal (−) of the current detection operational amplifier 7 and the drain terminal of the transistor 8. The output of the current detection operational amplifier 7 is connected to the gate terminal of the transistor 8. The source terminal of the transistor 8 is connected to one terminal of the current detection resistor 9. The other terminal of the current detection resistor 9 is connected to the negative terminal of the auxiliary power supply 10. The plus / minus power supply terminal of the current detection operational amplifier 7 is connected to the plus terminal / auxiliary power supply 10 minus terminal of the auxiliary power supply 81. In this current detection circuit 2, an auxiliary power supply 10 is necessary to generate a sufficient detection voltage in the current detection resistor 9, and the GND potential of the negative terminal of the main power supply 3 is used as a reference voltage, which is lower than this reference voltage. The current detection circuit 2 is operating at the potential.

  Further, the control unit 20 includes an addition / subtraction circuit 82 instead of the subtraction circuit 21, and the voltage across the current detection resistor 9 is input to the addition / subtraction circuit 82, but only the voltage output from the auxiliary power supply 10. Since the voltage is low, an auxiliary power supply 81 that outputs the same voltage as the auxiliary power supply 10 is provided, and the voltage of the auxiliary power supply 81 is added to the voltage across the current detection resistor 9 via the resistor 83. The output of the addition / subtraction circuit 82 can detect a voltage proportional to the load current from the GND potential, and transmits the load current information to the control circuit 22.

  In the seventh embodiment, the GND potential at the minus terminal of the main power supply 3 is used as a reference voltage, and the adder / subtractor circuit 82 detects a voltage proportional to the load current from the GND potential and transmits the detected voltage to the control circuit 22, so that It is possible to obtain the same effects as those of Embodiments 1 and 2.

(Embodiment 8)
FIG. 8 shows an example of the configuration of a semiconductor device on which the power supply circuit according to the eighth embodiment of the present invention is mounted.

  The semiconductor device according to the eighth embodiment describes a transistor package 90 having a current detection function as an example of a semiconductor element package based on the power supply circuit according to the second embodiment (FIG. 2). Needless to say, the configuration of the semiconductor device is not limited to the power supply circuit of the second embodiment, but can also be applied to the case where the power supply circuit of the first embodiment or the third to seventh embodiments is mounted.

  The transistor package 90 includes a power transistor chip 91 and a current detection IC chip 92.

  In the power transistor chip 91, the main transistor 4 and the sense transistor 5 are generated on the same substrate. By generating on the same substrate, the characteristics of the main transistor 4 and the sense transistor 5 are similar.

  The current detection IC chip 92 includes a current detection operational amplifier 7, transistors 8 and 93, an auxiliary power supply 10, a resistor 94, a subtraction circuit 21, an auxiliary power supply generation circuit 95, and the like. In this current detection IC chip 92, a transistor 93 and a resistor 94 are added between the main transistor 4, the load 6, and the current adjustment signal input terminal 11, and auxiliary power generation for generating a voltage of the auxiliary power supply 10 is performed. A circuit 95 is also added.

  The current detection resistor 9 is connected to the outside of the current detection IC chip 92 in order to ensure resistance accuracy. In addition, the main power supply 3, the load 6, the control circuit 22, and the reference power supply 96 are also connected to the outside.

  In such a configuration, the reference power supply 96 for generating the voltage of the auxiliary power supply is input to the transistor package 90, and the auxiliary power supply generation circuit 95 in the current detection IC chip 92 is based on the voltage of the reference power supply 96. A voltage of the auxiliary power supply 10 is generated. The voltage generated at both ends of the current detection resistor 9 is input to the subtraction circuit 21, and the output of the subtraction circuit 21 is input to the control circuit 22 to drive the main power supply 3.

  In the eighth embodiment, in addition to the power supply circuit of the second embodiment, the first embodiment also applies to a semiconductor device mounted with the power supply circuit of the first embodiment or the third to seventh embodiments. Since the detection accuracy improvement effect and the significant loss reduction effect can be obtained in the same manner as in .about.7, etc., it is possible to configure a semiconductor device equipped with a highly accurate and low loss power supply circuit.

  Further, in a semiconductor device (transistor package 90) equipped with a power supply circuit as in the present embodiment, a control circuit 22 using the power supply circuit, or a control device using the control circuit 22 (main power supply 3, load 6, a device including a current detection resistor 9, a control circuit 22, and a reference power source 96).

  Although the invention made by the present inventor has been specifically described based on the eight embodiments, the present invention can also be used in combination with these embodiments.

  Further, the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist thereof. For example, in the above-described embodiment, MOSFETs are used as the main transistor 4 and the sense transistor 5, but these transistors may be composed of bipolar transistors, IGBTs, or the like.

  In the above description, the invention made mainly by the present inventor has been described in the light of the dimming switch of the LED power source, which is the field of use behind the invention, but the present invention is intended to detect the current flowing through the transistor, that is, It can be widely used as a high-side switch and a low-side switch for a step-up switching regulator, a high-side switch and a low-side switch for a step-down switching regulator, or a load switch for various electronic devices.

It is a figure which shows an example of a structure of the power supply circuit in Embodiment 1 of this invention. It is a figure which shows an example of a structure of the power supply circuit in Embodiment 2 of this invention. It is a figure which shows an example of a structure of the power supply circuit in Embodiment 3 of this invention. It is a figure which shows an example of a structure of the power supply circuit in Embodiment 4 of this invention. It is a figure which shows an example of a structure of the power supply circuit in Embodiment 5 of this invention. It is a figure which shows an example of a structure of the power supply circuit in Embodiment 6 of this invention. It is a figure which shows an example of a structure of the power supply circuit in Embodiment 7 of this invention. It is a figure which shows an example of a structure of the semiconductor device carrying the power supply circuit in Embodiment 8 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main circuit, 2 ... Current detection circuit, 3 ... Main power supply, 4 ... Main transistor, 5 ... Sense transistor, 6 ... Load, 7 ... Current detection operational amplifier, 8 ... Transistor, 9 ... Current detection resistance, 10 ... Auxiliary Power supply, 11 ... input terminal,
DESCRIPTION OF SYMBOLS 20 ... Control part, 21 ... Subtraction circuit, 22 ... Control circuit, 23 ... Operational amplifier, 24, 25, 26, 27 ... Resistance, 28 ... Operational amplifier, 29 ... Comparator, 30 ... Reference voltage, 31, 32 ... Resistance, 33 ... Capacitors, 34, 35 ... power source, 36 ... triangular wave generator,
40, 41 ... voltage dividing resistor, 42 ... power supply,
50, 51 ... Voltage dividing resistor, 52 ... Reference voltage, 53 ... Comparator, 54 ... Power supply,
60, 61, 62, 63 ... transistor, 64 ... current detection resistor,
71, 72, 73, 74 ... switches,
81 ... Auxiliary power supply, 82 ... Addition / subtraction circuit, 83 ... Resistance,
DESCRIPTION OF SYMBOLS 90 ... Transistor package, 91 ... Power transistor chip, 92 ... Current detection IC chip, 93 ... Transistor, 94 ... Resistor, 95 ... Auxiliary power generation circuit, 96 ... Reference power supply

Claims (13)

A first power source for supplying a load current; a first transistor for adjusting the load current; a second transistor having characteristics similar to those of the first transistor; and a current detection connected to the second transistor. A first terminal of the first transistor and one terminal of the second transistor connected to each other between source terminals or emitter terminals, or between drain terminals or collector terminals; A power supply circuit in which a feedback loop is formed to control the same voltage applied to the other terminal of the second transistor and the other terminal of the second transistor,
One end of the first power supply is used as a reference potential, the second power supply has a second power supply connected to the reference potential, and the second power supply supplies a current flowing through the second transistor. Power supply circuit. The power supply circuit according to claim 1,
Furthermore, an operational amplifier connected to the other terminal of the first transistor and the other terminal of the second transistor is provided, and a feedback loop for controlling the same voltage is configured using the operational amplifier. Power supply circuit. The power supply circuit according to claim 2,
The power supply circuit, wherein the second power supply supplies driving power for the operational amplifier. The power supply circuit according to claim 2,
The power supply circuit further comprises a circuit for reducing an offset voltage of the operational amplifier. The power supply circuit according to claim 2,
The power supply circuit further includes a switch for cutting off a current flowing through the current detection resistor when the first transistor is off. The power supply circuit according to claim 2,
And a circuit for converting a reference value of a detection voltage in the current detection resistor into a ground potential. The power supply circuit according to claim 2,
The power supply circuit further includes a control unit that controls a power supply voltage of the first power supply, and a part of the control unit operates based on a voltage at one end of the second power supply.   A semiconductor device comprising the power supply circuit according to claim 1. A first transistor for adjusting a load current; a second transistor having characteristics similar to those of the first transistor; and a source of one terminal of the first transistor and one terminal of the second transistor The first transistor and the second transistor are semiconductor devices configured on the same first substrate, wherein terminals or emitter terminals, drain terminals or collector terminals are connected to each other.
The semiconductor device has a second substrate different from the first substrate, constitutes a circuit for detecting a current on the second substrate, and a detection current or a detection voltage depending on a load current Output. The semiconductor device according to claim 9.
A semiconductor device, wherein a feedback loop is formed to control the voltage applied to the other terminal of the first transistor and the other terminal of the second transistor in the same manner. The semiconductor device according to claim 10.
On the second substrate, an operational amplifier connected to the other terminal of the first transistor and the other terminal of the second transistor is configured, and a feedback loop for controlling the voltage equally is provided on the operational amplifier. A semiconductor device characterized by being used. The semiconductor device according to claim 11,
A current detection resistor is connected to the outside of the semiconductor device, and a reference potential of a voltage generated at both ends of the current detection resistor is a second voltage having a voltage lower than the voltage of the first power supply from the voltage of the first power supply. A semiconductor device having a potential obtained by subtracting a voltage of a power source. The semiconductor device according to claim 12,
On the second substrate, a subtraction circuit for converting a reference value of a detection voltage in the current detection resistor into a ground potential and an auxiliary power generation circuit for generating a voltage of the second power source are configured. A semiconductor device.

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