CN203434864U - Step-down switching type power supply unit - Google Patents
Step-down switching type power supply unit Download PDFInfo
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- CN203434864U CN203434864U CN201320490888.2U CN201320490888U CN203434864U CN 203434864 U CN203434864 U CN 203434864U CN 201320490888 U CN201320490888 U CN 201320490888U CN 203434864 U CN203434864 U CN 203434864U
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Abstract
The utility model provides a step-down switching type power supply unit. The step-down switching type power supply unit comprises a power level, a drive circuit and a bootstrap capacitor. The power level comprises an upper bridge switch, a lower bridge switch and an inductor; the upper bridge switch is electrically connected between an input end and a switching node; and the lower bridge switch is electrically connected between the switching node and the ground. The inductance drive circuit is used to control operation of the upper bridge switch and the lower bridge switch. The bootstrap capacitor is electrically connected between a voltage-boosting node and a switching node, and the voltage-boosting node is electrically connected with a supply voltage. When a cross voltage of the bootstrap capacitor is less than a reference voltage, the lower bridge switch is conductive, so the bootstrap capacitor is charged with a self-supply voltage; and, when charging reaches a predetermined period, or when an inductor current reaches a default value, the bootstrap capacitor is not charged any more.
Description
Technical field
The utility model relates to a kind of voltage-dropping type switched power supply, refers to especially the efficient voltage reducing type switched power supply that a kind of whole efficiency of energy utilization is good.
Background technology
Fig. 1 illustrates the schematic diagram of existing voltage-dropping type switched power supply.The power stage 11 of existing voltage-dropping type switched power supply 10 comprises bridge switch MA, lower bridge switch MB and inductance L, is jointly electrically connected on a switching node Lx, and controlled by drive circuit 12.The upper bridge drive circuit 121 that drive circuit 12 comprises and lower bridge drive circuit 122 drive signal S122 according to the first driving signal S121 and second respectively, produce the first operation signal SA and the second operation signal SB, with the conducting (ON) of switching upper bridge switch MA and lower bridge switch MB with close (OFF), to send electric energy to output OUT(drive circuit 12 other from input IN, partly omit).
When the input voltage vin providing when power supply is high pressure; for enough driving forces are provided; as shown in Figure 1; existing voltage-dropping type switched power supply 10 conventionally can be between the supply voltage Vdd of drive circuit 12 inside and the source electrode of upper bridge switch MA; meaning arranges a bootstrap capacitor CBOOT boosting between node VBOOT and switching node Lx, so that required pressure reduction between the grid of upper bridge switch MA and source electrode to be provided.The cross-pressure Vcap of bootstrap capacitor CBOOT is in order to be provided as the operating voltage of upper bridge drive circuit 121.During bridge switch MB conducting instantly, the supply voltage Vdd of self-driven circuit 12 inside is through 13 pairs of bootstrap capacitor CBOOT chargings of diode, while making that bridge switch MB closes instantly, the voltage of node VBOOT of boosting can arrive Vcap+VLx, pressure reduction therefore boost between the voltage (VLx) of the voltage of node VBOOT (Vcap+VLx) and switching node Lx can arrive Vcap, required to keep supplying 121 operations of bridge drive circuit.The object that diode 13 is set is during higher than supply voltage Vdd, to prevent that electric current from entering supply voltage Vdd from the node VBOOT adverse current of boosting at the voltage of the node VBOOT that boosts, thereby infringement supply voltage Vdd.When output OUT connects a system load 16 or a battery (not illustrating), when the pattern of system load 16 in power consumption, meaning is when the existing voltage-dropping type switched power supply 10 of needs provides electric energy, because continuing switched conductive, upper bridge switch MA and lower bridge switch MB to send electric energy to output OUT from input IN, offer system load 16 with the action of closing, therefore bootstrap capacitor CBOOT will often be recharged renewal, and it is accurate that the cross-pressure on it can remain on the position needing.
Yet, when system load 16 is in standby mode, meaning is when system load 16 Bu Mao electricity or only slightly during power consumption, now because not needing to send electric energy to output OUT from input IN, therefore upper bridge switch MA and lower bridge switch MB all close and are failure to actuate, bootstrap capacitor CBOOT will can not be recharged renewal in the case, and the electric charge in it can run off and cross-pressure is declined gradually.And at some time points, when system load 16 recovers again action and while entering the pattern of power consumption, now existing voltage-dropping type switched power supply 10 needs again to provide electric energy to output OUT again, but due to cause the boosting undertension of node VBOOT of the cross-pressure deficiency on bootstrap capacitor CBOOT, therefore the actuating force of upper bridge drive circuit 121 cannot conducting on bridge switch MA, therefore existing voltage-dropping type switched power supply 10, when restarting, must first charge to bootstrap capacitor CBOOT.Its charging modes is bridge switch MB under first conducting, makes switching node Lx be connected in ground, so supply voltage Vdd can be through 13 pairs of bootstrap capacitor CBOOT chargings of diode.
Please refer to Fig. 2, it shows the schematic diagram that existing voltage-dropping type switched power supply 10 wastes energy.Above-mentioned, from standby mode, return in the process of pattern, due to (" the restarting " to during time point T1 from time point as shown in Figure 2 of bridge switch MB under must first conducting, meaning is descended the ON time (ON-time) of bridge switch MB is Δ TB), therefore cause electric current to flow in reverse direction bridge switch MB from output OUT.Again, from time point T1 to time point T2 during, when upper bridge switch MA conducting, when lower bridge switch MB closes, electric current can be from output OUT flow in reverse direction bridge switch MA.More than action, because the ON time (ON-time) of lower bridge switch MB is that Δ TB is long, thus too much from the electric energy of output OUT back transfer, so will cause the waste of whole energy efficiency, if and control improperly, will cause the boost operations to input IN from output OUT.In addition,, when output OUT is connected in a battery (not illustrating), can make this battery constantly discharge.
In order to address the aforementioned drawbacks, in US Patent No. 7235955, propose a solution, but its control mode is comparatively complicated.
In view of this, the utility model, for above-mentioned the deficiencies in the prior art, proposes a kind of efficient voltage reducing type switched power supply that can improve whole energy efficiency utilization.
Summary of the invention
The purpose of this utility model is to overcome the deficiencies in the prior art and defect, proposes a kind of efficient voltage reducing type switched power supply that can improve whole energy efficiency utilization.
For reaching above-mentioned purpose, just wherein a viewpoint is sayed, the utility model provides a kind of voltage-dropping type switched power supply, in order to the input voltage that an input is provided, be converted to an output voltage in an output, comprise: (1) one power stage, comprise: bridge switch on, its one end is electrically connected on this input, and its other end is electrically connected on a switching node; Bridge switch once, its one end is electrically connected on this switching node, and its other end is electrically connected on ground; And an inductance, its one end is electrically connected on this switching node, and its other end is electrically connected on this output; (2) one bootstrap capacitors, are electrically connected on one and boost between node and this switching node, and this node that boosts are electrically connected on a supply voltage; And (3) one drive circuit, in order to control the operation of bridge switch and this lower bridge switch on this, this drive circuit comprises: one controls signal generating circuit, it produces controls signal to determine the ON time of bridge switch and this lower bridge switch on this; An and bootstrap capacitor charging control circuit, whether its cross-pressure that judges this bootstrap capacitor is less than a reference voltage, when the cross-pressure of this bootstrap capacitor is less than this reference voltage, this bootstrap capacitor charging control circuit output signal is controlled signal generating circuit to this, and with this lower bridge switch of conducting, this supply voltage charges to this bootstrap capacitor certainly.
A kind of, preferably implement in kenel, whether the judgement of this bootstrap capacitor charging control circuit has reached a scheduled time slot from the cross-pressure of this bootstrap capacitor is less than this reference voltage, and when arriving this scheduled time slot, this bootstrap capacitor charging control circuit output signal is controlled signal generating circuit to this, to stop this lower bridge switch of conducting.
A kind of, preferably implement in kenel, this bootstrap capacitor charging control circuit comprises: a comparison circuit, by the cross-pressure of this bootstrap capacitor and this reference voltage comparison, to produce a comparison circuit output signal; One ON time timer, when the output signal of this comparison circuit shows that the cross-pressure of this bootstrap capacitor is less than this reference voltage, this ON time timer starts to calculate a scheduled time slot, and when arriving this scheduled time slot, this ON time timer produces a timing output signal; And a latch circuit, it receives this comparison circuit output signal and this timing output signal as setting and reseting signal.
A kind of, preferably implement in kenel, this bootstrap capacitor charging control circuit judges whether the electric current of this inductance arrives a reference current, and when the electric current of this inductance arrives this reference current, this bootstrap capacitor charging control circuit output signal is controlled signal generating circuit to this, to stop this lower bridge switch of conducting.
A kind of, preferably implement in kenel, this bootstrap capacitor charging control circuit comprises: a comparison circuit, by the cross-pressure of this bootstrap capacitor and this reference voltage comparison, to produce a comparison circuit output signal; One current comparison circuit, the relatively electric current of this inductance and a reference current and generation current signal relatively; And a latch circuit, its receive this comparison circuit output signal and this current ratio compared with signal as setting and reseting signal.
A kind of, preferably implement in kenel, this voltage-dropping type switched power supply also comprises a diode, and its anode is electrically connected on this supply voltage, and its cathodic electricity is connected in this node that boosts.
A kind of, preferably implement in kenel, this voltage-dropping type switched power supply also comprises a power protection switch, and its one end is electrically connected on this input, and its other end is electrically connected on bridge switch on this, in order to a power supply of protecting this input to connect.
A kind of, preferably implement in kenel; this power protection switch comprises a transistor; be electrically connected on this input and on this between bridge switch; this transistor has a parasitic diode; the anode-cathode direction of this parasitic diode can stop that on this bridge switch flows to the reverse current of this input, or this transistor has the parasitic diode of adjustable polarity.
A kind of, preferably implement in kenel, this output is electrically connected on a system load or a battery.
A kind of, preferably implement in kenel, this output is electrically connected on this battery via a transistor, this transistor has a parasitic diode, the anode-cathode direction of this parasitic diode can stop the electric current that flows to this battery from this output, or this transistor has the parasitic diode of adjustable polarity, to control the charging to this battery.
Below by specific embodiment, illustrate in detail, when the effect that is easier to understand the purpose of this utility model, technology contents, feature and reaches.
Accompanying drawing explanation
Fig. 1 shows the schematic diagram of existing voltage-dropping type switched power supply;
Fig. 2 shows the schematic diagram that existing voltage-dropping type switched power supply wastes energy;
Fig. 3 shows the schematic diagram of the efficient voltage reducing type switched power supply of first embodiment of the utility model;
Fig. 4 shows the embodiment schematic diagram of bootstrap capacitor charging control circuit of the present utility model;
Fig. 5 shows another embodiment schematic diagram of bootstrap capacitor charging control circuit of the present utility model;
Fig. 6 shows the good schematic diagram of the more existing voltage-dropping type switched power supply of the utility model efficiency of energy utilization;
Fig. 7 A-7B shows several embodiment of power protection switch of the present utility model;
Fig. 8 A-8C shows that output of the present utility model is electrically connected on several embodiment of system load or battery.
Symbol description in figure
(prior art)
10 existing voltage-dropping type switched power supplies
12 existing drive circuits
The existing time of T1～T3
The existing ON time of Δ TB
(the utility model)
20 voltage-dropping type switched power supplies
11 power stages
Bridge drive circuit on 121
122 times bridge drive circuits
123 comparison circuits
124 latch circuits
125 ON time timers
126 current comparison circuits
13 diodes
14 power protection switches
16 system loads
22 drive circuits
221 control signal generating circuit
222 bootstrap capacitor charging control circuits
BAT battery
CBOOT bootstrap capacitor
FB feedbacks signal
IL inductive current
IN input
Iref reference current
L inductance
Lx switching node
The upper bridge switch of MA
Bridge switch under MB
N1 node
OUT output
Q1, Q3 transistor
Q2, Q4 is adjustable polar transistor
R resistance
S121 first drives signal
S122 second drives signal
SA the first operation signal
SB the second operation signal
T1～t3 time
The Δ tb reference time
The VBOOT node that boosts
Vcap cross-pressure
Vdd supplies voltage
Vin input voltage
VLx switching node voltage
Vout output voltage
Vref reference voltage
Embodiment
About aforementioned and other technology contents, feature and effect of the present utility model, in the following detailed description coordinating with reference to a graphic preferred embodiment, can clearly present.The direction term of mentioning in following examples, such as: upper and lower, left and right, front or rear etc., is only the direction with reference to annexed drawings.Graphic in the utility model all belongs to signal, be mainly intended to represent the function relation between each device and each element, as for shape, thickness and width not according to scale.
Please refer to Fig. 3, it shows the schematic diagram of the voltage-dropping type switched power supply of first embodiment of the utility model.The voltage-dropping type switched power supply 20 of the present embodiment comprises a power stage 11, one drive circuit 22 and a bootstrap capacitor CBOOT, and in addition optionally (nonessential) comprises a diode 13 and a power protection switch 14.The power stage 11 of the voltage-dropping type switched power supply 20 of the present embodiment comprises upper bridge switch MA, lower bridge switch MB and an inductance L.Upper bridge switch MA, lower bridge switch MB and inductance L are electrically connected on a switching node Lx jointly, and controlled by drive circuit 22.In the present embodiment, upper bridge switch MA is such as but not limited to can be nmos pass transistor, and lower bridge switch MB is such as but not limited to can be nmos pass transistor or PMOS transistor.In detail, one end of upper bridge switch MA is electrically connected on input IN, and its other end is electrically connected on switching node Lx.One end of lower bridge switch MB is electrically connected on switching node Lx, the ground connection and its other end is electrically connected.One end of inductance L is electrically connected on switching node Lx, and its other end is electrically connected on output OUT.Drive circuit 22 comprises bridge drive circuit 121, lower upper bridge drive circuit 121, controls signal generating circuit 221 and bootstrap capacitor charging control circuit 222.Control signal generating circuit 221 and produce the first driving signal S121 and the second driving signal S122, and the upper bridge drive circuit 121 that drive circuit 22 comprises and lower bridge drive circuit 122 drive signal S122 according to the first driving signal S121 and second respectively, produce the first operation signal SA and the second operation signal SB, to switch the conducting (ON) of upper bridge switch MA and lower bridge switch MB and to close (OFF), to send electric energy to output OUT from input IN.When normal running, control signal generating circuit 221 for example can produce the first driving signal S121 and second according to back coupling signal FB and drive signal S122 to determine the ON time of upper bridge switch MA and lower bridge switch MB, and back coupling signal FB for example can be relevant to output voltage V out or inductive current IL; In the time of need to charging when the voltage drop of bootstrap capacitor CBOOT, control signal generating circuit 221 and can produce the first driving signal S121 and second according to the output of bootstrap capacitor charging control circuit 222 and drive signal S122.
In the present embodiment, output OUT can be electrically connected to a system load (not illustrating) or a battery (not illustrating) (the several embodiment that are electrically connected on system load or battery about output OUT hold rear explanation), accordingly system load or battery is powered.The present embodiment arranges a bootstrap capacitor CBOOT boost between node VBOOT and a node N1 (meaning is boosting between node VBOOT and switching node Lx), so that required pressure reduction between the grid of upper bridge switch MA and source electrode to be provided.Bootstrap capacitor CBOOT is the operating voltage in order to bridge drive circuit 121 on being provided as at the cross-pressure Vcap boosting between node VBOOT and switching node Lx.In the present embodiment, bootstrap capacitor CBOOT is such as but not limited to the outside that is arranged at drive circuit 22.In other embodiment, bootstrap capacitor CBOOT also can be integrated into the inside of drive circuit 22.The present embodiment also comprises a diode 13, and its anode is electrically connected on a supply voltage Vdd of drive circuit 22 inside, and its cathodic electricity is connected in the node VBOOT that boosts, and wherein supplies voltage Vdd such as but not limited to obtaining from input voltage vin.The object of diode 13 being set as previously mentioned, is during higher than supply voltage Vdd, to prevent that electric current from entering supply voltage Vdd from the adverse current of the node VBOOT that boosts at the voltage of the node VBOOT that boosts, thereby infringement supply voltage Vdd.
Below illustrate how the utility model utilizes electric energy expeditiously.
Please refer to Fig. 3-6.When system load (not illustrating) is wanted to enter pattern from standby mode (no-load or underloading), voltage-dropping type switched power supply 20 need restart under upper bridge switch MA and all pent state of lower bridge switch MB.Now, the cross-pressure Vcap of bootstrap capacitor CBOOT reduces because of the loss of electric charge, so that is not enough to be provided as the operating voltage of bridge drive circuit 121.
As shown in Figure 4, in the first execution mode, in bootstrap capacitor charging control circuit 222, can comprise comparison circuit 123, latch circuit 124, ON time timer 125.Comparison circuit 123 judges whether cross-pressure Vcap is less than a reference voltage Vref and produces comparison circuit output signal, when wherein, the position of reference voltage Vref will definitely be restarted with reference to the required actuating force of upper bridge switch MA and voltage-dropping type switched power supply 20, the desirable reaction time is decided.If cross-pressure Vcap is less than reference voltage Vref, the comparison circuit output signal that comparison circuit 123 produces is set the output of (set) latch circuit 124, so " restart " to (as shown in Figure 6) during time point t1 from time point, control bridge switch MB under signal generating circuit 221 conductings, during this, upper bridge switch MA is in closed condition.During bridge switch MB conducting instantly, the voltage of switching node Lx (VLx) is 0V because of ground connection, causes supply voltage Vdd via 13 pairs of bootstrap capacitor CBOOT chargings of diode.Therefore the pressure reduction between the voltage (Vcap+VLx) of the node VBOOT that boosts and the voltage (VLx) of switching node Lx can arrive Vcap, required to keep supplying 121 operations of bridge drive circuit.
Owing to " restarting " from time point to during time point t1, while namely descending bridge switch MB conducting, electric current flow to bridge switch MB in reverse direction from output OUT.Too much in order to prevent from the electric energy of output OUT back transfer, and cause the waste of whole energy efficiency, the utility model provides two kinds of solutions, and a kind of is when bootstrap capacitor CBOOT is charged, and controls the ON time of lower bridge switch MB; Another kind is when bootstrap capacitor CBOOT is charged, detecting inductive current IL.This two kinds of solutions are below described.
In the first execution mode shown in Fig. 4, in bootstrap capacitor charging control circuit 222, be provided with an ON time timer 125, when bootstrap capacitor CBOOT is charged, control the ON time (meaning i.e. " restarting " to during time point t1 from time point as shown in Figure 6, namely Δ tb) of lower bridge switch MB.As cross-pressure Vcap, to be less than reference voltage Vref so that comparison circuit output signal conversion position punctual, and this time lights certainly, and ON time timer 125 starts timing; When timing arrives scheduled time slot (corresponding to Δ tb), ON time timer 125 produces the output that timing output signal is reseted (reset) latch circuit 124, and control signal generating circuit 221, stops accordingly bridge switch MB under conducting.
Accordingly, the utility model, when restarting or other need to charge to bootstrap capacitor CBOOT, on the one hand judges whether cross-pressure Vcap is less than a reference voltage Vref, if so, bridge switch MB under conducting; And on the other hand, the utility model utilizes conducting timer 125, determine the ON time that stops of lower bridge switch MB, prevent accordingly from the electric energy of output OUT back transfer too much.
Next, please see the second solution.As shown in Figure 5, in the second execution mode, in bootstrap capacitor charging control circuit 222, can comprise comparison circuit 123, latch circuit 124, current comparison circuit 126.Comparison circuit 123 judges whether cross-pressure Vcap is less than a reference voltage Vref and produces comparison circuit output signal, if cross-pressure Vcap is less than reference voltage Vref, expression need to be charged to bootstrap capacitor CBOOT, the comparison circuit output signal that now comparison circuit 123 produces is set the output of (set) latch circuit 124, so control bridge switch MB under signal generating circuit 221 conductings, corresponding to " restarting " time point in Fig. 6.On the other hand, current comparison circuit 126 judges whether inductive current IL arrives reference current Iref and generation current signal relatively, the default value of reference current Iref for needing to determine based on design wherein, such as can and avoiding electric current to flow and too much make voltage-dropping type switched power supply 20 become the reverse considerations such as voltage up converting circuit to decide this default value from output OUT in the other direction according to the inductance value of the charging demand of bootstrap capacitor CBOOT, inductance L.When current comparison circuit 126 judgement inductive current IL arrive reference current Iref, its current ratio producing is reseted the output of (reset) latch circuit 124 compared with signal, and control signal generating circuit 221, stop accordingly bridge switch MB under conducting.。
Refer to Fig. 6, at upper bridge drive circuit 122, close (time after time point t1) after lower bridge switch MB, upper bridge switch MA can be by conducting smoothly (because the pressure reduction boosting between the voltage (Vcap+VLx) of node VBOOT and the voltage (VLx) of switching node Lx now can arrive Vcap, required to keep supplying 121 operations of bridge drive circuit).And after time point t2, upper bridge switch MA and lower bridge switch MB have recovered normal switch mode, therefore again from input IN, send electric energy to output OUT, so that system load is powered.
Consult Fig. 6 known, the utility model has the advantages that: because the utility model is when restarting, under conducting, the ON time of bridge switch MB only has Δ tb, therefore, when bootstrap capacitor CBOOT is charged again, from output OUT, flow in reverse direction the electric current of bridge switch MB, compared to existing voltage-dropping type switched power supply 10, only belong to very a small amount of, can significantly reduce power consumption.In addition, because the reverse trend on inductive current is less, therefore the utility model is difficult for entering reverse boost operations, and (the ON time Δ tb of lower bridge switch MB is less than ON time Δ TB can more early to recover normal handover operation, therefore time point t2 is early than time point T2), therefore the utility model is obviously better than prior art.
Please refer to Fig. 7 A-7B, it shows that the utility model arranges several embodiment of power protection switch 14.In some application of the present utility model, can between input IN and upper bridge switch MA, a power protection switch 14 (as shown in Figure 3) be set, this power protection switch 14 has the function that prevents electric current adverse current.Power protection switch 14 comprises the transistor Q2 (as shown in Figure 7 B) of a transistor Q1 (as shown in Figure 7 A) or an adjustable parasitic diode polarity.In Fig. 7 A illustrated embodiment, the parasitic diode anode of transistor Q1 is electrically connected on input IN, its cathodic electricity is connected in bridge switch MA, that is the parasitic diode polarity of transistor Q1 and the parasitic diode opposite polarity directions of upper bridge switch MA, therefore when the voltage of upper that end of bridge switch MA is during higher than input voltage vin, the parasitic diode of transistor Q1 can stop the reverse current that flows to input IN from upper bridge switch MA.Or, can be as shown in Figure 7 B, because the polar orientation of the parasitic diode of transistor Q2 is adjustable, therefore when the voltage of upper that end of bridge switch MA is during higher than input voltage vin, for preventing electric current adverse current, can make the opposite direction of anode-cathode direction and the electric current adverse current of this parasitic diode; Again for example when the voltage of upper that end of bridge switch MA lower than input voltage vin and for prevent electric current from input voltage vin following current to during that end of bridge switch MA (for example, while wanting to stop the operation of voltage-dropping type switched power supply 20), make the anode-cathode direction of this parasitic diode and the opposite direction of electric current following current.The function of power protection or control so, can be provided.
Please refer to Fig. 8 A-8C, it shows that output of the present utility model is electrically connected on several embodiment of system load or battery.Output OUT of the present utility model can be electrically connected on a system load 16 or a battery BAT.System load 16 is such as but not limited to can be hand-hold electronic device or other external equipment etc.; And battery BAT includes or external battery such as but not limited to can be device or Mobile electric power etc.Please refer to an embodiment as shown in Figure 8 A, output OUT can be electrically connected on system load 16 and battery BAT via a resistance R, and resistance R can be detected output current and produce back coupling signal accordingly, to control the charging to battery BAT.Please refer to another embodiment as shown in Figure 8 B, output OUT can be electrically connected on battery BAT via a transistor Q3, by controlling the conducting state of transistor Q3, can control the charging of output voltage V out to battery BAT.In addition, please refer to another embodiment as shown in Figure 8 C, output OUT can be electrically connected on battery BAT via the transistor Q4 of an adjustable parasitic diode polarity, by controlling the conducting state of transistor Q4, can control the charging of output voltage V out to battery BAT.Adjustable polar transistor Q4 has the adjustable parasitic diode of a polar orientation, when charging to battery BAT, output OUT can make anode-cathode direction and this charging opposite direction of parasitic diode, the anode that can make again parasitic diode in the time need to charging to bootstrap capacitor CBOOT towards output OUT and negative electrode towards battery BAT, to avoid the improper electric discharge of battery BAT.
Below for preferred embodiment, the utility model is described, just the above, only, for making those skilled in the art be easy to understand content of the present utility model, be not used for limiting interest field of the present utility model.Under same spirit of the present utility model, those skilled in the art can think and various equivalence changes.For example, shown in each embodiment circuit, can insert the element that does not affect signal major significance, as other switch etc.Again for example, if control the outputting level of signal generating circuit 221, enough drive bridge switch MA and lower bridge switch MB, go up bridge drive circuit 121 and lower bridge drive circuit 122 can omit.Again for example, comparison circuit is not limited to comparator, and as the state switching points of smith trigger (Smith trigger) is located to reference voltage Vref, smith trigger also has comparing function and can be considered a kind of comparison circuit.Again for example, in embodiment and icon, comparison circuit 123 is by cross-pressure Vcap and reference voltage Vref comparison, and current comparison circuit 126 is compared inductive current IL with reference current Iref, this is only for representing concept, also can the dividing potential drop of cross-pressure Vcap and the voltage ratio of reference voltage Vref, or the ratio value of inductive current IL is compared with the ratio value of reference current Iref, should be considered as equivalence.Again for example, " setting " of latch circuit 124 and " reseting " are inputted interchangeable, only need the corresponding processing mode that changes its output.All this kind, all can analogize and obtain according to teaching of the present utility model, and therefore, scope of the present utility model should contain above-mentioned and other all equivalence variations.In addition, arbitrary enforcement kenel of the present utility model needn't be reached all objects or advantage, and therefore, any one of claim should be as limit yet.
Claims (10)
1. a voltage-dropping type switched power supply, is converted to an output voltage in an output in order to the input voltage that an input is provided, and it is characterized in that, comprises:
One power stage, comprising:
Bridge switch on one, its one end is electrically connected on this input, and its other end is electrically connected on a switching node;
Bridge switch once, its one end is electrically connected on this switching node, and its other end is electrically connected on ground; And
One inductance, its one end is electrically connected on this switching node, and its other end is electrically connected on this output;
One bootstrap capacitor, is electrically connected on one and boosts between node and this switching node, and this node that boosts is electrically connected on a supply voltage; And
One drive circuit, in order to control the operation of bridge switch and this lower bridge switch on this, this drive circuit comprises:
One controls signal generating circuit, and it produces controls signal to determine the ON time of bridge switch and this lower bridge switch on this; And
One bootstrap capacitor charging control circuit, whether its cross-pressure that judges this bootstrap capacitor is less than a reference voltage, when the cross-pressure of this bootstrap capacitor is less than this reference voltage, this bootstrap capacitor charging control circuit output signal is controlled signal generating circuit to this, and with this lower bridge switch of conducting, this supply voltage charges to this bootstrap capacitor certainly.
2. voltage-dropping type switched power supply as claimed in claim 1, it is characterized in that, whether the judgement of this bootstrap capacitor charging control circuit has reached a scheduled time slot from the cross-pressure of this bootstrap capacitor is less than this reference voltage, and when arriving this scheduled time slot, this bootstrap capacitor charging control circuit output signal is controlled signal generating circuit to this, to stop this lower bridge switch of conducting.
3. voltage-dropping type switched power supply as claimed in claim 1, is characterized in that, this bootstrap capacitor charging control circuit comprises:
One comparison circuit, by the cross-pressure of this bootstrap capacitor and this reference voltage comparison, to produce a comparison circuit output signal;
One ON time timer, when the output signal of this comparison circuit shows that the cross-pressure of this bootstrap capacitor is less than this reference voltage, this ON time timer starts to calculate a scheduled time slot, and when arriving this scheduled time slot, this ON time timer produces a timing output signal; And
One latch circuit, it receives this comparison circuit output signal and this timing output signal as setting and reseting signal.
4. voltage-dropping type switched power supply as claimed in claim 1, it is characterized in that, this bootstrap capacitor charging control circuit judges whether the electric current of this inductance arrives a reference current, and when the electric current of this inductance arrives this reference current, this bootstrap capacitor charging control circuit output signal is controlled signal generating circuit to this, to stop this lower bridge switch of conducting.
5. voltage-dropping type switched power supply as claimed in claim 1, is characterized in that, this bootstrap capacitor charging control circuit comprises:
One comparison circuit, by the cross-pressure of this bootstrap capacitor and this reference voltage comparison, to produce a comparison circuit output signal;
One current comparison circuit, the relatively electric current of this inductance and a reference current and generation current signal relatively; And
One latch circuit, its receive this comparison circuit output signal and this current ratio compared with signal as setting and reseting signal.
6. voltage-dropping type switched power supply as claimed in claim 1, is characterized in that, also comprises a diode, and its anode is electrically connected on this supply voltage, and its cathodic electricity is connected in this node that boosts.
7. voltage-dropping type switched power supply as claimed in claim 1, is characterized in that, also comprises a power protection switch, and its one end is electrically connected on this input, and its other end is electrically connected on bridge switch on this, in order to a power supply of protecting this input to connect.
8. voltage-dropping type switched power supply as claimed in claim 7; it is characterized in that; this power protection switch comprises a transistor; be electrically connected on this input and on this between bridge switch; this transistor has a parasitic diode; the anode-cathode direction of this parasitic diode can stop that on this bridge switch flows to the reverse current of this input, or this transistor has the parasitic diode of adjustable polarity.
9. voltage-dropping type switched power supply as claimed in claim 1, is characterized in that, this output is electrically connected on a system load or a battery.
10. voltage-dropping type switched power supply as claimed in claim 9, it is characterized in that, this output is electrically connected on this battery via a transistor, this transistor has a parasitic diode, the anode-cathode direction of this parasitic diode can stop the electric current that flows to this battery from this output, or this transistor has the parasitic diode of adjustable polarity, to control the charging to this battery.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320490888.2U CN203434864U (en) | 2013-08-12 | 2013-08-12 | Step-down switching type power supply unit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320490888.2U CN203434864U (en) | 2013-08-12 | 2013-08-12 | Step-down switching type power supply unit |
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| CN203434864U true CN203434864U (en) | 2014-02-12 |
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| CN201320490888.2U Expired - Fee Related CN203434864U (en) | 2013-08-12 | 2013-08-12 | Step-down switching type power supply unit |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2018103664A1 (en) * | 2016-12-07 | 2018-06-14 | 华为技术有限公司 | Direct current-to-direct current converter and fault protection method |
| CN109119969A (en) * | 2017-06-26 | 2019-01-01 | 立锜科技股份有限公司 | Overvoltage protection method, step-down switching power supply and control circuit thereof |
| CN109494978A (en) * | 2017-09-12 | 2019-03-19 | 力智电子股份有限公司 | Integrated circuit of power supply switching circuit and power supply switching controller |
-
2013
- 2013-08-12 CN CN201320490888.2U patent/CN203434864U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2018103664A1 (en) * | 2016-12-07 | 2018-06-14 | 华为技术有限公司 | Direct current-to-direct current converter and fault protection method |
| CN109119969A (en) * | 2017-06-26 | 2019-01-01 | 立锜科技股份有限公司 | Overvoltage protection method, step-down switching power supply and control circuit thereof |
| CN109119969B (en) * | 2017-06-26 | 2020-03-31 | 立锜科技股份有限公司 | Overvoltage protection method, step-down switching power supply and control circuit thereof |
| CN109494978A (en) * | 2017-09-12 | 2019-03-19 | 力智电子股份有限公司 | Integrated circuit of power supply switching circuit and power supply switching controller |
| CN109494978B (en) * | 2017-09-12 | 2021-01-26 | 力智电子股份有限公司 | Integrated circuit of power supply switching circuit and power supply switching controller |
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Granted publication date: 20140212 Termination date: 20170812 |