JP2020140384A - Power supply circuit - Google Patents

Abstract

To appropriately prevent an output voltage from rising when an output is stopped.SOLUTION: A power supply circuit 22 is comprised of: an output circuit OUT (P21, A21, R21, R22) that generates an output voltage Vout from an input voltage Vin by using an output transistor P21; a leak detection circuit DET that generates a first current I23 according to a leak current Ileak of an output transistor P21 (leak detection transistor P23 formed by the same process as the output transistor P21 and driven by a drive signal G21 common to the output transistor P21); and a leak absorption circuit ABS (N22, N23, R24) that draws a second current I24 corresponding to the first current I23 from the output circuit OUT. The power supply circuit 22 also comprises a switch circuit SWC (P24, LVS) that cuts off the first current I23 when the output circuit OUT is in an operating state (EN=H); and that conducts the first current I23 when the output circuit OUT is in a non-operating state (EN=L).SELECTED DRAWING: Figure 3

Description

The invention disclosed herein relates to a power supply circuit.

Power supply circuits capable of generating a desired output voltage from an input voltage are installed in various applications (vehicle-mounted equipment, industrial equipment, office equipment, digital home appliances, portable equipment, etc.).

As an example of the prior art related to the above, Patent Document 1 can be mentioned.

Japanese Unexamined Patent Publication No. 2012-226421

By the way, in a conventional power supply circuit, generally, while the output operation is stopped, the output terminal is set to a low potential end by using a low impedance discharge circuit so that the output voltage does not rise due to a leak current or the like. For example, it has a function to short-circuit to the grounding end). However, for example, in an application in which a separate external power supply is connected to the output terminal of the power supply circuit, the current flowing through the discharge circuit may not be ignored from the viewpoint of reducing current consumption.

An object of the invention disclosed in the present specification is to provide a power supply circuit capable of appropriately preventing an increase in output voltage when the output is stopped, in view of the above problems found by the inventor of the present application. And.

The power supply circuit disclosed in the present specification includes an output circuit that generates an output voltage from an input voltage using an output transistor, a leak detection circuit that generates a first current corresponding to the leak current of the output transistor, and a leak detection circuit. It has a configuration (first configuration) including a leak absorption circuit that draws a second current corresponding to the first current from the output circuit.

In the power supply circuit having the first configuration, the leak detection circuit may have a configuration (second configuration) including a leak detection transistor formed by the same process as the output transistor.

Further, in the power supply circuit having the second configuration, the leak detection transistor may be configured to be always off (third configuration).

Further, in the power supply circuit having the second configuration, the leak detection transistor may be driven by a drive signal common to the output transistor (fourth configuration).

Further, in the power supply circuit having any of the first to fourth configurations, the leak absorption circuit may have a configuration including a current mirror circuit, a source grounded circuit, or an emitter grounded circuit (fifth configuration).

Further, the power supply circuit having any of the first to fifth configurations cuts off the first current when the output circuit is in the operating state, and the first power circuit when the output circuit is in the non-operating state. It is preferable to have a configuration (sixth configuration) further including a switch circuit for conducting current.

Further, in the power supply circuit having any of the first to sixth configurations, the leak absorption circuit is in a non-operating state when the output circuit is in an operating state, and is in a non-operating state when the output circuit is in a non-operating state. It is preferable to use a configuration (seventh configuration) that is in an operating state.

Further, in the power supply circuit having any of the first to seventh configurations, the output transistor is connected between the input end of the input voltage and the output end of the output voltage, and the output voltage is the target. The on-resistance value may be continuously controlled so as to match the value (eighth configuration).

Further, in the power supply circuit having any of the first to seventh configurations, the output transistor is connected between the input end of the input voltage and the application end of the switch voltage to rectify the switch voltage. The on-duty may be controlled so that the output voltage generated by smoothing matches the target value (nineth configuration).

Further, the vehicle disclosed in the present specification has a configuration having a power supply circuit having any of the above-mentioned first to ninth configurations and a load receiving power supply from the power supply circuit (tenth configuration). It is said that.

According to the invention disclosed in the present specification, it is possible to provide a power supply circuit capable of appropriately preventing the output voltage from rising when the output is stopped.

Diagram showing a comparative example of a power supply circuit The figure which shows the 1st Embodiment of a power supply circuit The figure which shows the 2nd Embodiment of a power supply circuit The figure which shows the 3rd Embodiment of a power supply circuit The figure which shows the 4th Embodiment of a power supply circuit The figure which shows the 5th Embodiment of a power supply circuit The figure which shows the 6th Embodiment of a power supply circuit Diagram showing the appearance of the vehicle

<Power supply circuit (comparative example)>
First, before explaining a new embodiment of the power supply circuit, a comparative example to be compared with this will be briefly described.

FIG. 1 is a diagram showing a comparative example of a power supply circuit. The power supply circuit 20 of this comparative example is a linear power supply that generates an output voltage Vout with the input voltage Vin stepped down and supplies it to the load Z, and is a P-channel type MOS field effect transistor P21 (= output transistor) and an N-channel type. It has a MOS field effect transistor N21 (= discharge transistor), an operational amplifier A21, resistors R21 to R23, and an inverter INV.

The source and back gate of the transistor P21 are connected to the input end of the input voltage Vin. The drain of each of the transistors P21 and N21 and the first end of the resistor R22 are connected to the output end of the output voltage Vout. The source and back gate of transistor N21 are connected to the ground end. An inverting enable signal ENB in which the logic level of the enable signal EN is inverted is input to the gate of the transistor N21 via an inverter INV. The second end of the resistor R22 is connected to the first end of the resistor R21. The second end of the resistor R21 is connected to the grounded end. The non-inverting input end (+) of the operational amplifier A21 is connected to a connection node (= application end of the feedback voltage Vfb) between the resistors R21 and R22. The inverting input end (−) of the operational amplifier A21 is connected to the application end of the reference voltage Vref. The output end of the operational amplifier A21 is connected to the gate of the transistor P21. The resistor R23 is connected between the gate and source of the transistor P21. An enable signal EN is input to the operational amplifier A21. The resistors R21 and R22 may be omitted, and the output voltage Vout may be directly input to the operational amplifier A21 as the feedback voltage Vfb.

The operational amplifier A21 linearly controls the gate signal G21 of the transistor P21 so that the feedback voltage Vfb (= Vout × {R21 / (R21 + R22)}) corresponding to the output voltage Vout matches the predetermined reference voltage Vref. That is, the on-resistance value of the transistor P21 is continuously controlled so that the output voltage Vout matches the target value (= Vref × {(R21 + R22) / R21}).

As described above, the transistor P21, the operational amplifier A21, and the resistors R21 and R22 function as an output circuit OUT that generates an output voltage Vout from the input voltage Vin by using the output transistor (= transistor P21).

The output circuit OUT can switch its operating state / non-operating state according to the enable signal EN. For example, when EN = H, the operational amplifier A21 linearly controls the gate signal G21 to continuously control the on-resistance value of the transistor P21. That is, when EN = H, the output circuit OUT is in the operating state. On the other hand, when EN = L, the operational amplifier A21 is in the output high impedance state, and the gate signal G21 is pulled up to the input voltage Vin. That is, when EN = L, the output circuit OUT is in a non-operating state. As the control signal for switching the operating state / non-operating state of the output circuit OUT, a UVLO [under voltage locked out] signal or the like may be used instead of the enable signal EN.

By the way, high resistance (for example, about several MΩ) is generally used for the resistors R21 and R22 for determining the target value of the output voltage Vout from the viewpoint of low power consumption. Therefore, when the leakage current Ileak of the transistor P21 flows through the resistors R21 and R22 in the non-operating state (EN = L) of the output circuit OUT, an unintended lift (= Ileak × (R21 + R22)) occurs in the output voltage Vout.

In particular, the leak current Ileak increases as the size of the transistor P21 increases and as the junction temperature Tj or the ambient temperature Ta of the IC in which the power supply circuit 20 is integrated becomes higher (for example, 150 ° C. or higher).

Therefore, when the size of the transistor P21 is large and the junction temperature Tj or the ambient temperature Ta is high, if a leak current Ileak exceeding the permissible value flows into the resistors R21 and R22, in the worst case, the output voltage Vout is input. The voltage rises to Vin, which may cause the load Z to be destroyed or the system to malfunction.

In order to solve such a problem, the power supply circuit 20 is provided with a transistor N21 for output discharge. The transistor N21 is turned on when EN = L (that is, ENB = H) to short the output end of the output voltage Vout to the ground end. Therefore, it is possible to eliminate the rise of the output voltage Vout caused by the leak current Ileak.

However, for example, in an application in which a separate external power supply E is connected to the output terminal (= output end of the output voltage Vout) of the power supply circuit 20, while EN = L, the path α (= external power supply) in the figure The current is wasted through the current path from E to the ground end via the transistor N21).

In the following, we propose a new embodiment that can solve the above problems.

<Power supply circuit (first embodiment)>
FIG. 2 is a diagram showing a first embodiment of a power supply circuit. In the power supply circuit 21 of the first embodiment, a P-channel type MOS field-effect transistor P22 and an N-channel type MOS field-effect transistor are used instead of the transistor N21 and the inverter INV, based on the above-mentioned comparative example (FIG. 1). It has N22 and N23, and a resistor R24.

The gate and source of the transistor P22 are connected to the input end of the input voltage Vin. The drain of the transistor P22 is connected to the drain of the transistor N22. The gates of the transistors N22 and N23 are connected to the drain of the transistor N22. The source of transistor N22 is connected to the first end of resistor R24. The second end of the resistor R24 and the source of the transistor N23 are connected to the ground end. The drain of the transistor N23 is connected to the output end of the output voltage Vout.

The transistor P22 is a leak detection transistor formed by the same process as the transistor P21, and generates a first current I21 corresponding to the leak current Ileak of the transistor P21 as a component of the leak detection circuit DET. For example, when the size ratio of the transistors P21 and P22 is m: 1, I21 = Ileak × (1 / m). The transistor P22 is always off.

The transistors N22 and N23 and the resistor R24 form a current mirror circuit that generates a second current I22 corresponding to the first current I21, and as a component of the leak absorption circuit ABS, the second from the output end of the output voltage Vout. 2 Pull in the current I22.

For example, in the non-operating state (EN = L) of the output circuit OUT, when the junction temperature Tj or the ambient temperature Ta of the IC is low and the leakage current Ileak hardly flows, the transistor N23 hardly draws the second current I22 and outputs. The output end of the voltage Vout is in a substantially high impedance state. On the other hand, when the junction temperature Tj or the ambient temperature Ta of the IC becomes high and the leakage current Ileak increases, the impedance of the transistor N23 decreases, so that a larger second current I22 is drawn in.

In this way, if the configuration is such that the leak current Ileak flowing through the transistor P21 is detected and the impedance of the leak absorption circuit ABS (the on-resistance value of the transistor N23 in this figure) is controlled according to the detection result, the output voltage Vout is set. Even when the external power supply E is connected to the output end, the second current I22 is not unnecessarily drawn. Therefore, it is possible to more appropriately prevent the output voltage Vout from rising when the output is stopped, and there is no possibility that the load Z will be destroyed or the system will malfunction.

By setting the gain of the current mirror circuit to m times or more (ideally m times), I22 ≧ Ileak, so that the leak current Ileak of the transistor P21 can be reliably absorbed.

<Power supply circuit (second embodiment)>
FIG. 3 is a diagram showing a second embodiment of the power supply circuit. In the power supply circuit 22 of the second embodiment, the P-channel type MOS field effect transistor P23 is used instead of the transistor P22, based on the first embodiment (FIG. 2) described above, and further, the P-channel is used. A type MOS field effect transistor P24, an N channel type MOS field effect transistor N24, and a level shifter LVS have been added.

The source of the transistor P23 is connected to the input end of the input voltage Vin. The gate of the transistor P23 is connected to the output end (= application end of the gate signal G21) of the operational amplifier A21. The drain of the transistor P23 is connected to the source of the transistor P24. The drains of the transistors P24 and N24 are connected to the drains of the transistors N22. The source of the transistor N24 is connected to the ground end. The gate of the transistor N24 and the input end of the level shifter LVS are connected to the application end of the enable signal EN. The output end of the level shifter LVS is connected to the gate of the transistor P24.

The transistor P23 is a leak detection transistor formed by the same process as the transistor P21, and as a component of the leak detection circuit DET, when the output circuit OUT is in the non-operating state (EN = L), the transistor P21 The first current I23 corresponding to the leak current Ileak is generated. For example, when the size ratio of the transistors P21 and P23 is m: 1, I23 = Ileak × (1 / m).

Unlike the transistor P22 (FIG. 2) described above, the transistor P23 is not always off, but is driven by a gate signal G21 common to the transistor P21. For example, when the output circuit OUT is in the non-operating state (EN = L), the transistors P21 and P23 are turned off in the same manner by the pull-up of the gate signal G21. Therefore, the first current I23 flowing through the transistor P23 more accurately reflects the leak current Ileak as compared with the first current I21 flowing through the transistor P22.

The transistors N22 and N23 and the resistor R24 form a current mirror circuit that generates a second current I24 corresponding to the first current I23, and as a component of the leak absorption circuit ABS, the second from the output end of the output voltage Vout. 2 Pull in the current I24. In this respect, there is no difference from the first embodiment (FIG. 2).

The transistor P24 and the level shifter LVS form a switch circuit SWC that conducts / cuts off between the drain of the transistor P23 and the drain of the transistor N22 in response to the enable signal EN. More specifically, the level shifter LVS receives the input of the enable signal EN (H = Vcc, L = GND) and outputs the second enable signal EN2 (H = Vin, L = Vin-5V). The transistor P24 is turned off when EN2 = H and turned on when EN2 = L.

That is, the switch circuit SWC cuts off the first current I23 when the output circuit OUT is in the operating state (EN = H), and the first current I23 when the output circuit OUT is in the non-operating state (EN = L). Conducts. Therefore, when it is not necessary to absorb the leak current Ileak of the transistor P21 (EN = H), the first current I23 does not flow unnecessarily, and the second current I24 does not flow from the output end of the output voltage Vout. You won't be drawn in as needed.

The transistor N24 is a component of the leak absorption circuit ABS, and is turned on / off according to the enable signal EN. More specifically, the transistor N24 is turned on when EN = H and turned off when EN = L.

When the transistor N24 is turned on, the gates of the transistors N22 and N23 are short-circuited to the ground end, so that the current mirror circuit becomes invalid. On the other hand, when the transistor N24 is off, the gates of the transistors N22 and N23 are separated from the ground end, so that the current mirror is effective.

As described above, with the introduction of the transistor N24, the leak absorption circuit ABS is in the non-operating state when the output circuit OUT is in the operating state (EN = H), and the output circuit OUT is in the non-operating state (EN = L). Sometimes it goes into operation.

Of course, if the switch circuit SWC is introduced, the first current I23 and the second current I24 will not flow unnecessarily even if the transistor N24 is not provided. However, it is preferable to introduce the transistor N24 in the leak absorption circuit ABS so that the gates of the transistors N22 and N23 do not have an indefinite potential when the transistor P24 is turned off.

Further, although not shown again, the switch circuit SWC (= transistor P24 and level shifter LVS) or transistor N24 may be introduced in the first embodiment (FIG. 2) described above.

<Power supply circuit (third embodiment)>
FIG. 4 is a diagram showing a third embodiment of the power supply circuit. In the power supply circuit 23 of the third embodiment, the transistor N22 is omitted while being based on the second embodiment (FIG. 3) described above. That is, the leak absorption circuit ABS includes a source grounded circuit instead of the current mirror circuit.

As shown in parentheses in this figure, the source grounded circuit may be replaced with an emitter grounded circuit by using an npn type bipolar transistor instead of the transistor N23. As described above, the means for generating the second current I24 by multiplying the gain of the first current I23 is not limited to the current mirror circuit.

In particular, when the size ratio of the transistors P21 and P23 (and the current ratio of the leak current Ileak and the first current I23) is large and it is necessary to increase the gain of the leak absorption circuit ABS, the current mirror circuit is used instead. It is desirable to use a grounded-source circuit (or a grounded-emitter circuit).

Further, although not shown again, the current mirror circuit may be replaced with a source grounded circuit (or an emitter grounded circuit) based on the first embodiment (FIG. 2) described above.

<Power supply circuit (fourth embodiment)>
FIG. 5 is a diagram showing a fourth embodiment of the power supply circuit. In the power supply circuit 24 of the fourth embodiment, based on the second embodiment (FIG. 3) described above, instead of the transistors P24 and the level shifter LVS, N-channel type MOS field effect transistors N25 and N26 and a resistor R25 are used. It is provided.

The drain of the transistor N25 is connected to the drain of the transistor P23. The source of transistor N25 is connected to the drain of transistor N22. The first end of the resistor R25 is connected to the power supply end. The second end of the resistor R25 and the drain of the transistor N26 are connected to the gate of the transistor N25. The source of transistor N26 is connected to the ground end. The gate of the transistor N26 is connected to the application end of the enable signal EN.

The transistor N26 and the resistor R25 function as an inverter that generates an inverting enable signal ENB in which the logic level of the enable signal EN is inverted and outputs the inverting enable signal ENB to the gate of the transistor N25. Therefore, the transistor N25 is turned off when EN = H (ENB = L) and turned on when EN = L (ENB = H).

As described above, if the N-channel type transistor N25 is used instead of the P-channel type transistor P24, the level shifter LVS can be omitted.

Further, although not shown again, the transistor P24 and the level shifter LVS may be replaced with the transistors N25 and N26 and the resistor R25 based on the third embodiment (FIG. 4) described above.

<Power supply circuit (fifth embodiment)>
FIG. 6 is a diagram showing a fifth embodiment of the power supply circuit. The power supply circuit 25 of the fifth embodiment is based on the second embodiment (FIG. 3) described above, and the overcurrent protection circuit OCP (P-channel type MOS field effect transistors P25 and P26, N-channel type MOS field effect transistor). N27 and resistors R26 and R27) have been added.

The source of each of the transistors P25 and P26 and the first end of the resistor R27 are connected to the input end of the input voltage Vin. The gate of the transistor P26 and the second end of the resistor R27 are connected to the drain of the transistor N27. The gate of the transistor P25 and the drain of the transistor P26 are connected to the output end (= application end of the gate signal G21) of the operational amplifier A21. The drain of the transistor P25 and the gate of the transistor N27 are connected to the first end of the resistor R26. The source of the transistor N27 and the second end of the resistor R26 are connected to the output end of the output voltage Vout.

The transistor P25 is a sense transistor formed by the same process as the transistor P21, and is an output of the transistor P21 as a component of the overcurrent protection circuit OCP when the output circuit OUT is in the operating state (EN = H). A sense current Is is generated according to the current Iout. For example, when the size ratio of the transistors P21 and P25 is n: 1, Is = Iout × (1 / n).

The resistor R26 functions as a current / voltage conversion element that converts the sense current Is into a sense voltage Vs (= Is × R26 + Vout).

The sense voltage Vs rises as the output current Iout increases, and when the gate-source voltage Vgs (= Vs-Vout) of the transistor N27 exceeds the on-threshold voltage Vth, the transistor N27 turns on. At this time, the gate voltage of the transistor P26 drops from a high level (≈Vin) to a low level (≈Vout), so that the transistor P26 is turned on. As a result, the gate signal G21 is pulled up to a high level (≈Vin), so that the transistor P21 is forcibly turned off.

By providing such an overcurrent protection circuit OCP, the transistor P21 is forcibly turned off when the output current Iout reaches a predetermined overcurrent detection threshold Iocp (≈n × Vth / R26), and the output current Iout is provided. Can be quickly cut off, so that the safety of the power supply circuit 25 can be enhanced.

When the output circuit OUT is in the non-operating state (EN = L), a sense current Is (= Ileak × (1 / n)) corresponding to the leak current Ileak of the transistor P21 flows through the transistor P25. However, since Ileak << Iout, the transistor N27 (and thus the transistor P26) does not turn on.

Further, although not shown again, the overcurrent protection circuit is based on the above-mentioned first embodiment (FIG. 2), third embodiment (FIG. 4), or fourth embodiment (FIG. 5). OCP may be added.

<Power supply circuit (sixth embodiment)>
FIG. 7 is a diagram showing a sixth embodiment of the power supply circuit. In the power supply circuit 26 of the sixth embodiment, an application example to a switching power supply (DC / DC converter) is shown instead of the conventional linear power supply. More specifically, the power supply circuit 26 includes a P-channel type MOS field effect transistor P27 (= output transistor), a diode D21, an inductor L21, a capacitor C21, and a controller CTRL as components of the output circuit OUT. , The leak detection circuit DET, the leak absorption circuit ABS, and the switch circuit SWC described above.

The source and back gate of the transistor P27 are connected to the input end of the input voltage Vin. The drain of the transistor P27 and the cathode of the diode D21 are connected to the first end of the inductor L21 (= the application end of the switch voltage Vsw). The anode of the diode D21 is connected to the ground end. The gate of the transistor P27 is connected to the controller CDR. The second end of the inductor L21 and the first end of the capacitor C21 are connected to the output end of the output voltage Vout. The second end of the capacitor C21 is connected to the ground end.

The diode D21, the inductor L21, and the capacitor C21 correspond to a rectifying and smoothing circuit that rectifies and smoothes a rectangular wave-shaped switch voltage Vsw to generate an output voltage Vout. A synchronous rectifier transistor can be used instead of the diode D21.

The controller CDRL controls the on-duty of the transistor P27 (= Ton / T, where T is the switching cycle and Ton is the on-time of the transistor P27) so that the output voltage Vout matches the target value. As for the output feedback method of the controller CTRL, well-known techniques such as PWM [pulse width modulation] method and PFM [pulse frequency modulation] method may be applied, so detailed description thereof will be omitted.

The output circuit OUT can switch its operating state / non-operating state according to the enable signal EN input to the controller CTRL. For example, when EN = H, the controller CTRL is in a state of pulse-driving the gate signal G22 to control the on-duty of the transistor P27. That is, when EN = H, the output circuit OUT is in the operating state. On the other hand, when EN = L, the controller CTRL is in the output high impedance state, and the gate signal G22 is pulled up to the input voltage Vin. That is, when EN = L, the output circuit OUT is in a non-operating state.

The leak detection circuit DET generates a first current I25 corresponding to the leak current Ileak of the transistor P27.

The leak absorption circuit ABS generates a second current I26 corresponding to the first current I25 and draws it from the output circuit OUT (for example, the application end of the switch voltage Vsw or the output end of the output voltage Vout). The leak absorption circuit ABS accepts the input of the enable signal EN, and is in the non-operating state when the output circuit OUT is in the operating state (EN = H), and the output circuit OUT is in the non-operating state (EN = L). When is, it becomes the operating state.

The switch circuit SWC cuts off the first current I25 when the output circuit OUT is in the operating state (EN = H), and conducts the first current I25 when the output circuit OUT is in the non-operating state (EN = L). To do.

Since the configurations of the leak detection circuit DET, the leak absorption circuit ABS, and the switch circuit SWC are as described above, duplicate explanations will be omitted.

As described above, the output rise prevention mechanism using the leak detection circuit DET and the leak absorption circuit ABS can be applied not only to the linear power supply but also to the switching power supply.

<Application to vehicles>
FIG. 8 is a diagram showing the appearance of the vehicle. The vehicle X of this configuration example is equipped with various electronic devices X11 to X18 that operate by receiving electric power from a battery (not shown). The mounting positions of the electronic devices X11 to X18 in this figure may differ from the actual mounting positions for convenience of illustration.

The electronic device X11 is an engine control unit that performs control related to the engine (injection control, electronic throttle control, idling control, oxygen sensor heater control, auto cruise control, etc.).

The electronic device X12 is a lamp control unit that controls turning on and off such as HID [high intensity discharged lamp] and DRL [daytime running lamp].

The electronic device X13 is a transmission control unit that performs control related to the transmission.

The electronic device X14 is a braking unit that performs controls related to the movement of the vehicle X (ABS [anti-lock brake system] control, EPS [electric power steering] control, electronic suspension control, etc.).

The electronic device X15 is a security control unit that controls drive such as a door lock and a security alarm.

The electronic device X16 is an electronic device incorporated in the vehicle X at the factory shipment stage as a standard equipment such as a wiper, an electric door mirror, a power window, a damper (shock absorber), an electric sunroof, and an electric seat as a manufacturer's option. Is.

The electronic device X17 is an electronic device that is optionally mounted on the vehicle X as a user option such as an in-vehicle A / V [audio / visual] device, a car navigation system, and an ETC [electronic toll collection system].

The electronic device X18 is an electronic device provided with a high withstand voltage motor such as an in-vehicle blower, an oil pump, a water pump, and a battery cooling fan.

The power supply circuits 21 to 26 described above can be incorporated into any of the electronic devices X11 to X18.

<Other variants>
In addition to the above-described embodiment, various technical features disclosed in the present specification can be modified in various ways without departing from the spirit of the technical creation. For example, mutual replacement between a bipolar transistor and a MOS field effect transistor and logic level inversion of various signals are arbitrary. That is, it should be considered that the above-described embodiment is exemplary in all respects and is not restrictive, and the technical scope of the present invention is not limited to the above-described embodiment, and claims for patent It should be understood that the meaning equivalent to the scope of and all changes belonging to the scope are included.

The invention disclosed in the present specification can be used in a power supply circuit mounted in various applications (vehicle-mounted equipment, industrial equipment, office equipment, digital home appliances, portable equipment, etc.).

20-26 Power supply circuit A21 Operational amplifier ABS Leak absorption circuit C21 Capacitor CTRL controller D21 Diode DET Leak detection circuit E External power supply EN Enable signal G21, G22 Gate signal INV Inverter L21 Inductor LVS Level shifter N21-N27 N-channel type MOS field effect transistor OCP Current protection circuit OUT output circuit P21-P27 P-channel type MOS field effect transistor R21-R27 Resistance SWC switch circuit X Vehicle X11-X18 Electronic equipment Z Load

Claims (10)

An output circuit that uses an output transistor to generate an output voltage from an input voltage,
A leak detection circuit that generates a first current according to the leak current of the output transistor, and
A leak absorption circuit that draws a second current corresponding to the first current from the output circuit, and
A power supply circuit characterized by having. The power supply circuit according to claim 1, wherein the leak detection circuit includes a leak detection transistor formed by the same process as the output transistor. The power supply circuit according to claim 2, wherein the leak detection transistor is always turned off. The power supply circuit according to claim 2, wherein the leak detection transistor is driven by a drive signal common to the output transistor. The power supply circuit according to any one of claims 1 to 4, wherein the leak absorption circuit includes a current mirror circuit, a source grounded circuit, or an emitter grounded circuit. Claims 1 to 1, further comprising a switch circuit that cuts off the first current when the output circuit is in an operating state and conducts the first current when the output circuit is in a non-operating state. The power supply circuit according to any one of claims 5. The leak absorption circuit is any of claims 1 to 6, wherein the leak absorption circuit is in a non-operating state when the output circuit is in an operating state, and is in an operating state when the output circuit is in a non-operating state. The power supply circuit described in item 1. The output transistor is connected between the input end of the input voltage and the output end of the output voltage, and the on-resistance value is continuously controlled so that the output voltage matches the target value. The power supply circuit according to any one of claims 1 to 7, wherein the power supply circuit is characterized. The output transistor is connected between the input end of the input voltage and the application end of the switch voltage, and is turned on so that the output voltage generated by rectifying and smoothing the switch voltage matches the target value. The power supply circuit according to any one of claims 1 to 7, wherein the duty is controlled. The power supply circuit according to any one of claims 1 to 9.
The load that receives power from the power supply circuit and
A vehicle characterized by having.

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