Current detection circuit, switching power supply controller, light-emitting element driver, and motor driver

Abstract

The invention provides a current detection circuit, a switching power supply controller, a light emitting element driver, and a motor driver. A current detection circuit (300) includes: a first comparator (COMP1) configured to compare a sensing voltage corresponding to a current flowing through a switching element when the switching element is turned on and a threshold voltage; and a determiner (C1, C2, CS1, CS2, Q4 to Q6, INV1, COMP2) configured to determine, based on an output of the first comparator, whether a timing at which a magnitude relationship between the sensing voltage and the threshold voltage is inverted after the switching element is turned on before a predetermined time elapses after the switching element is turned on.

Description

Technical Field

[0001] The present disclosure relates to a current detection circuit, a switching power supply controller, a light emitting element driver, and a motor driver. Background Art

[0002] In the prior art, as a technology for detecting the output current of a switching power supply device, there is a current detection method using the potential difference between both ends of a sensing resistor provided at a stage after a capacitor for smoothing the output voltage of the switching power supply device (for example, see Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-153621 Summary of the invention

[0006] In the above current detection method, it is impossible to detect the average current in each switching cycle. Therefore, it is impossible to achieve, for example, constant current control based on the average current in each switching cycle, overcurrent protection based on the average current in each switching cycle, etc.

[0007] According to the present disclosure, the current detection circuit includes: a first comparator, which is configured to compare a sensing voltage and a threshold voltage corresponding to a current flowing through the switching element when the switching element is turned on; and a determiner, which is configured to determine, based on the output of the first comparator, whether the moment when the magnitude relationship between the sensing voltage and the threshold voltage is reversed after the switching element is turned on is before a predetermined time after the switching element is turned on.

[0008] A switching power supply controller according to the present disclosure includes the current detection circuit of the above configuration.

[0009] The light emitting element driver according to the present disclosure includes the current detection circuit of the above configuration.

[0010] A motor driver according to the present disclosure includes the current detection circuit of the above configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure.

[0012] Figure 1 is a schematic diagram showing a configuration of a switching power supply device according to an embodiment of the present disclosure.

[0013] Figure 2 is a schematic diagram showing an example of the operation of the current detection circuit.

[0014] Figure 3 is a schematic diagram showing an example of the operation of the current detection circuit.

[0015] Figure 4 is a schematic diagram showing an example of the operation of the current detection circuit.

[0016] Figure 5 is a schematic diagram showing an example of the operation of the current detection circuit.

[0017] Figure 6 is a schematic diagram showing a configuration of a switching power supply device according to a modification.

[0018] Figure 7 is a schematic diagram showing a schematic configuration example of a light emitting device.

[0019] Figure 8 is a schematic diagram showing a schematic configuration example of a motor device. DETAILED DESCRIPTION

[0020] Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other cases, well-known methods, procedures, systems, and components are not described in detail in order to avoid unnecessarily obscuring aspects of the various embodiments.

[0021] In the present disclosure, a metal oxide semiconductor (MOS) field effect transistor refers to a field effect transistor having a gate structure including at least three layers, the at least three layers being selected from the group consisting of “a layer made of a conductor or semiconductor (such as polysilicon) having a low resistance value”, “an insulating layer”, and “a P-type, N-type or intrinsic semiconductor layer”. That is, the gate structure of the MOS field effect transistor is not limited to a three-layer structure of metal, oxide, and semiconductor.

[0022] In the present disclosure, constant current refers to a current that is constant in an ideal state, and is actually a current that may slightly vary due to temperature changes and the like.

[0023] <Switching Power Supply Device>

[0024] Figure 11 is a schematic diagram showing the configuration of a switching power supply device according to an embodiment of the present disclosure. The switching power supply device 100 includes a switching power supply controller 200 (which is a semiconductor integrated circuit device), a P-channel MOS field effect transistor Q1 and an N-channel MOS field effect transistor Q2 (which are switching elements), an inductor L1, and an output capacitor C0. In the present embodiment, the switching element is externally connected to the switching power supply controller 200, but it can also be built into the switching power supply controller 200. In addition, in the present embodiment, the switching element is a MOS field effect transistor, but it can also be an element other than a MOS field effect transistor.

[0025] A P-channel MOS field effect transistor Q1 and an N-channel MOS field effect transistor Q2 are connected in series. The P-channel MOS field effect transistor Q1 is a high-side switch provided at a higher potential side than the N-channel MOS field effect transistor Q2. The N-channel MOS field effect transistor Q2 is a low-side switch provided at a lower potential side than the P-channel MOS field effect transistor Q1.

[0026] The power supply voltage VCC is applied to the source of the P-channel MOS field effect transistor Q1. The source of the N-channel MOS field effect transistor Q2 is connected to the ground potential. By performing a switching action between the P-channel MOS field effect transistor Q1 and the N-channel MOS field effect transistor Q2, a pulse-shaped switching voltage is generated at the connection node between the P-channel MOS field effect transistor Q1 and the N-channel MOS field effect transistor Q2.

[0027] The inductor L1 and the output capacitor C0 smooth a switching voltage generated at a connection node between the P-channel type MOS field effect transistor Q1 and the N-channel type MOS field effect transistor Q2 to generate an output voltage VOUT.

[0028] The switching power supply controller 200 includes a control section CNT1 , drivers D1 and D2 , and a current detection circuit 300 .

[0029] The control section CNT1 outputs control signals S1 and S2 based on the feedback voltage VFB. The feedback voltage VFB is a voltage based on the output voltage VOUT. The feedback voltage VFB may be the output voltage VOUT itself or may be a divided voltage of the output voltage VOUT. It is preferred that the control section CNT1 performs control to provide a dead time in which both the control signals S1 and S2 are at a low level.

[0030] In addition, the control unit CNT1 can perform control using the output OUT2 of the comparator COMP2. For example, the control unit CNT1 can perform constant current control based on the average current flowing through the inductor L1 in each switching cycle, perform overcurrent protection based on the average current flowing through the inductor L1 in each switching cycle, etc. In this case, the switching cycle refers to the cycle of switching action between the P-channel MOS field effect transistor Q1 and the N-channel MOS field effect transistor Q2.

[0031] The driver D1 supplies a gate drive signal obtained by amplifying the control signal S1 to the gate of the P-channel MOS field effect transistor Q1, thereby driving the P-channel MOS field effect transistor Q1. The driver D2 supplies a gate drive signal obtained by amplifying the control signal S2 to the gate of the N-channel MOS field effect transistor Q2, thereby driving the N-channel MOS field effect transistor Q2.

[0032] The current detection circuit 300 includes a switch SW1, a resistor R1, and a comparator COMP1. The current detection circuit 300 is provided with a power supply voltage VCC.

[0033] The switch SW1 is provided between each drain of the P-channel MOS field effect transistor Q1 and the N-channel MOS field effect transistor Q2 and the resistor R1 and the inverting input terminal of the comparator COMP1. When the control signal S1 is at a high level, the switch SW1 is turned on. When the control signal S1 is at a low level, the switch SW1 is turned off. The resistor R1 is a so-called pull-up resistor.

[0034] The sense voltage Vsns supplied to the inverting input terminal of the comparator COMP1 is a voltage corresponding to the current flowing through the P-channel type MOS field effect transistor Q1 when the P-channel type MOS field effect transistor Q1 is turned on (the current flowing through the inductor L1 when the P-channel type MOS field effect transistor Q1 is turned on). More specifically, the sense voltage Vsns supplied to the inverting input terminal of the comparator COMP1 is a voltage corresponding to the current flowing through the P-channel type MOS field effect transistor Q1 when the P-channel type MOS field effect transistor Q1 is turned on during the period when the switch SW1 is in the on state, and becomes equal to the power supply voltage VCC during the period when the switch SW1 is in the off state.

[0035] In addition, the sensing voltage Vsns is a voltage generated at the connection node between the P-channel MOS field effect transistor Q1 and the inductor L1. More specifically, the sensing voltage Vsns is a voltage generated at the connection node between the P-channel MOS field effect transistor Q1 and the inductor L1 during the period when the switch SW1 is in the on state, and becomes equal to the power supply voltage VCC during the period when the switch SW1 is in the off state. In the present embodiment, the sensing voltage Vsns is generated by the on-resistance of the P-channel MOS field effect transistor Q1. Therefore, it is not necessary to provide a sensing resistor for generating the sensing voltage Vsns, so that the power consumption in the sensing resistor can be eliminated. This suppresses the reduction in the efficiency of the switching power supply device.

[0036] The current detection circuit 300 further includes a P-channel MOS field effect transistor Q3 and a current source CS0. The P-channel MOS field effect transistor Q3 and the current source CS0 are examples of a voltage generator configured to generate a threshold voltage Vth. The threshold voltage Vth is supplied to a non-inverting input terminal of the comparator COMP1.

[0037] The power supply voltage VCC is applied to the source of the P-channel MOS field effect transistor Q3, and the gate of the P-channel MOS field effect transistor Q3 is connected to the ground potential. Therefore, the P-channel MOS field effect transistor Q3 is turned on and becomes a resistance element.

[0038] The current source CS0 is provided between the drain of the P-channel MOS field effect transistor Q3 and the ground potential. The current source CS0 causes a set current (reference current IREF) to flow through the P-channel MOS field effect transistor Q3. In the present embodiment, the value of the set current (reference current IREF) is fixed to one value, but it can be variable. For example, when the control unit CNT1 performs current mode control, the value of the set current (reference current IREF) can be changed according to the output signal of the error amplifier (not shown), the output signal of the error amplifier being based on the error between the feedback voltage based on the output voltage VOUT and the reference voltage.

[0039] The value (threshold value) of the voltage Vth is the product of the value of the set current (reference current IREF) and the value of the on-resistance of the P-channel MOS field effect transistor Q3.

[0040] In order to suppress the power consumption in the voltage generator configured to generate the threshold voltage Vth, it is preferred that the value of the on-resistance of the P-channel MOS field effect transistor Q3 is larger. Therefore, it is preferred that the value of the on-resistance of the P-channel MOS field effect transistor Q3 is greater than the value of the on-resistance of the P-channel MOS field effect transistor Q1. For example, the P-channel MOS field effect transistor Q1 and the P-channel MOS field effect transistor Q3 can be MOS field effect transistors having different ratios of channel width to channel length. Therefore, the on-resistance of the P-channel MOS field effect transistor Q1 and the on-resistance of the P-channel MOS field effect transistor Q3 can be easily set to different values.

[0041] It is preferable that the P-channel MOS field effect transistor Q3 is formed to maintain the paired property with the P-channel MOS field effect transistor Q1. When the P-channel MOS field effect transistors Q1 and Q3 have the paired property, the comparison result of the comparator COMP1 can be suppressed from being affected by temperature and the like.

[0042] The comparator COMP1 compares the sensing voltage Vsns and the threshold voltage Vth. When the sensing voltage Vsns is less than the threshold voltage Vth, the output OUT1 of the comparator COMP1 has a high level, and when the sensing voltage Vsns is greater than the threshold voltage Vth, the output OUT1 of the comparator COMP1 has a low level.

[0043] The current detection circuit 300 also includes a P-channel MOS field effect transistor Q4, current sources CS1 and CS2, capacitors C1 and C2, and N-channel MOS field effect transistors Q5 and Q6. The P-channel MOS field effect transistor Q4, the current sources CS1 and CS2, the capacitors C1 and C2, and the N-channel MOS field effect transistors Q5 and Q6 are examples of determiners. The determiner in this embodiment determines whether the moment when the magnitude relationship between the sense voltage Vsns and the threshold voltage Vth is reversed after the P-channel MOS field effect transistor Q1 is turned on is before a predetermined time has passed after the P-channel MOS field effect transistor Q1 is turned on, based on the output of the comparator COMP1.

[0044] The capacitor C1 is charged with the first constant current I1 through the P-channel type MOS field effect transistor Q4 and the current source CS1 configured to output the first constant current I1 until the magnitude relationship between the sense voltage Vsns and the threshold voltage Vth is reversed after the P-channel type MOS field effect transistor Q1 is turned on. The value of the charge voltage V1 of the capacitor C1 at the moment when the magnitude relationship between the sense voltage Vsns and the threshold voltage Vth is reversed is maintained until the P-channel type MOS field effect transistor Q1 is turned off.

[0045] After the magnitude relationship between the sensing voltage Vsns and the threshold voltage Vth is reversed, the capacitor C2 is charged with the second constant current I2 through the current source CS2 configured to output the second constant current I2.

[0046] When the P-channel type MOS field effect transistor Q1 is being turned off, the N-channel type MOS field effect transistor Q5 discharges the capacitor C1.

[0047] The inverter INV1 and the N-channel MOS field effect transistor Q6 discharge the capacitor C2 during the period from when the P-channel MOS field effect transistor Q1 is turned on until the magnitude relationship between the sense voltage Vsns and the threshold voltage Vth is reversed and during the period when the P-channel MOS field effect transistor Q1 is turned off.

[0048] The current detection circuit 300 further includes a comparator COMP2. The comparator COMP2 compares the charging voltage V1 of the capacitor C1 and the charging voltage V2 of the capacitor C2. When the charging voltage V1 of the capacitor C1 is greater than the charging voltage V2 of the capacitor C2, the output OUT2 of the comparator COMP2 has a low level, and when the charging voltage V1 of the capacitor C1 is less than the charging voltage V2 of the capacitor C2, the output OUT2 of the comparator COMP2 has a high level.

[0049] Figures 2 to 5 is a schematic diagram showing an operation example of the current detection circuit 300. Figures 2 to 5 , from top to bottom, a control signal S1, a control signal S2, a current IL flowing through an inductor L1, a sense voltage Vsns, a threshold voltage Vth, an output OUT1 of a comparator COMP1, a charging voltage V1 of a capacitor C1, a charging voltage V2 of a capacitor C2, and an output OUT2 of a comparator COMP2 are depicted. The charging voltage V2 of the capacitor C2 is depicted by a dotted line.

[0050] When operating from Figure 2 Move to Figure 5 When , the average value of the current IL flowing through the inductor L1 increases. That is, Figure 2 The average value of the current IL flowing through the inductor L1 is Figures 2 to 5 The smallest of the four states shown in . In contrast, Figure 5 The average value of the current IL flowing through the inductor L1 is Figures 2 to 5 The largest of the four states shown in .

[0051] For example, when the first constant current I1 and the second constant current I2 have the same value and the capacitance of capacitor C1 is the same as the capacitance of capacitor C2, it can be confirmed by the output OUT2 of comparator COMP2 whether the current IL flowing through inductor L1 exceeds a predetermined value (corresponding to the value of the threshold voltage Vth) at a time earlier than half of the period in which the P-channel MOS field effect transistor Q1 is turned on.

[0052] like Figures 2 to 4 As shown, when no pulse appears at the output OUT2 of the comparator COMP2, the current IL flowing through the inductor L1 does not exceed the set value (the value corresponding to the threshold voltage Vth) at a timing earlier than half of the period in which the P-channel MOS field effect transistor Q1 is turned on.

[0053] like Figure 5 As shown, when a pulse appears at the output OUT2 of the comparator COMP2, the current IL flowing through the inductor L1 exceeds the set value (the value corresponding to the threshold voltage Vth) at a timing earlier than half of the period in which the P-channel MOS field effect transistor Q1 is turned on.

[0054] There is a correlation between the instantaneous value of the current IL flowing through the inductor L1 when a predetermined time (e.g., half of the period during which the P-channel MOS field effect transistor Q1 is turned on) has passed after the P-channel MOS field effect transistor Q1 is turned on and the average value of the current IL flowing through the inductor L1 during the switching cycle. Therefore, the current detection circuit 300 can detect whether the average value of the current IL flowing through the inductor L1 in each switching cycle is greater than the set value.

[0055] For example, since the control unit CNT1 performs control to reduce the current IL flowing through the inductor L1 when a pulse appears at the output terminal OUT2 of the comparator COMP2 and conversely performs control to increase the current IL flowing through the inductor L1 when no pulse appears at the output terminal OUT2 of the comparator COMP2, the average value of the current IL flowing through the inductor L1 in each switching cycle can be maintained near the set value.

[0056] Figure 6 1 is a schematic diagram showing a configuration of a switching power supply device according to a modification. A switching power supply device 101 differs from the above-described switching power supply device 100 in that the former includes a sensing resistor R0 , a resistor R2 , and a switching power supply controller 201 instead of the switching power supply controller 200 .

[0057] The sensing resistor R0 is connected in series with the inductor L1 and is provided in a previous stage of the output capacitor C0. The resistor R2 is a resistance element having a larger resistance value than the sensing resistor R0 and having the same temperature characteristics as the sensing resistor R0.

[0058] The switching power supply controller 201 differs from the above-mentioned switching power supply controller 200 in that the former includes a current detection circuit 301 instead of the current detection circuit 300 .

[0059] The current detection circuit 301 is different from the current detection circuit 300 in that the former includes an amplifier AMP1 instead of the switch SW and the resistor R1 and does not include the P-channel MOS field effect transistor Q3, and the non-inverting input terminal and the inverting input terminal of the comparator COMP1 are exchanged. The amplifier AMP1 generates a sense voltage Vsns according to the potential difference between the two ends of the sense resistor R0, and supplies the sense voltage Vsns to the non-inverting input terminal of the comparator COMP1. The above-mentioned resistor R2 is a resistance element that replaces the P-channel MOS field effect transistor Q3.

[0060] <Application Examples>

[0061] Application examples of the current detection circuit are not limited to the switching power supply device. The current detection circuit configured as described above can be installed in, for example, a light emitting element driver, a motor driver, and the like.

[0062] Figure 7 4 is a schematic diagram showing a schematic configuration example of a light emitting device. The light emitting device 400 includes a light emitting element driver 401, an inductor 402, an N-channel MOS field effect transistor 403, an output capacitor 404, and a light emitting element 405. The light emitting element driver 401 drives the light emitting element 405 by controlling the N-channel MOS field effect transistor 403. The light emitting element driver 401 includes a current detection circuit 406.

[0063] Figure 8 500 is a schematic diagram showing a schematic configuration example of a motor device. The motor device 500 includes a motor driver 501, a three-phase inverter 502, and a three-phase motor 503. The motor driver 501 drives the three-phase motor 503 by controlling the three-phase inverter 502. The motor driver 501 includes a current detection circuit 504.

[0064] <Others>

[0065] In addition to the above-described embodiments, the configuration of the present disclosure may be modified in various ways without departing from the spirit of the present disclosure. The above-described embodiments should be considered to be illustrative rather than restrictive in all aspects. In addition, the technical scope of the present disclosure is defined by the claims, rather than by the description in the above-described embodiments, and it should be understood that the technical scope of the present disclosure includes all changes that fall within the meaning and scope equivalent to the claims.

[0066] In the above embodiment, the sense voltage is a voltage corresponding to the current flowing through the high-side switching element, but it may also be a voltage corresponding to the current flowing through the low-side switching element. In addition, the low-side switching element may be, for example, a diode.

[0067] <Notes>

[0068] The present disclosure will be provided with supplementary notes in which specific configuration examples are shown in the above-mentioned embodiments.

[0069] The current detection circuit (300, 301, 406, 504) of the present disclosure has a configuration (first configuration) including: a first comparator (COMP1), which is configured to compare a sensing voltage and a threshold voltage corresponding to a current flowing through the switching element when the switching element is turned on; and a determiner (C1, C2, CS1, CS2, Q4 to Q6, INV1, COMP2), which is configured to determine, based on an output of the first comparator, whether a moment when the magnitude relationship between the sensing voltage and the threshold voltage is reversed after the switching element is turned on is before a predetermined time after the switching element is turned on.

[0070] According to the current detection circuit of the first configuration, the average current in each switching cycle can be detected. More specifically, according to the current detection circuit of the first configuration, it is possible to detect whether the average current in each switching cycle is greater than a set value. Therefore, by using the current detection circuit of the first configuration, for example, constant current control based on the average current in each switching cycle, overcurrent protection based on the average current in each switching cycle, etc. can be achieved.

[0071] The current detection circuit of the first configuration may have a configuration (second configuration) in which the sense voltage may be a voltage generated at a connection node between the switching element and the inductor (L1).

[0072] The current detection circuit of the first or second configuration may have such a configuration (third configuration): the determiner includes: a first charger (CS1, Q4, C1), the first charger being configured to charge with a first constant current until the magnitude relationship between the sensing voltage and the threshold voltage is reversed after the switching element is turned on; a second charger (CS2, C2), the second charger being configured to charge with a second constant current after the magnitude relationship between the sensing voltage and the threshold voltage is reversed; and a second comparator (COMP2), the second comparator being configured to compare the charging voltage of the first charger with the charging voltage of the second charger.

[0073] The current detection circuit of the third configuration may have a configuration (fourth configuration) in which the determiner includes: a first discharger (Q5) configured to discharge the first charger during a period when the switching element is turned off; and a second discharger (Q6, INV1) configured to discharge the second charger during a period from when the switching element is turned on until the magnitude relationship between the sensing voltage and the threshold voltage is reversed and during a period when the switching element is turned off.

[0074] The current detection circuit of any one of the first to fourth configurations may have a configuration (fifth configuration) further comprising: a voltage generator configured to generate the threshold voltage, wherein the voltage generator comprises: a resistance element (Q3) having a resistance value greater than the on-resistance of the switching element; and a current source (CS0) configured to allow a set current to flow through the resistance element.

[0075] The current detection circuit of the fifth configuration may have a configuration (sixth configuration) in which the switch element and the resistance element are MOS field effect transistors having different ratios of channel width to channel length.

[0076] A switching power supply controller (200, 201) of the present disclosure has a configuration (seventh configuration) including a current detection circuit of any one of the first to sixth configurations.

[0077] The light emitting element driver (401) of the present disclosure has a configuration (eighth configuration) including the current detection circuit of any one of the first to sixth configurations.

[0078] The motor driver (501) of the present disclosure has a configuration (ninth configuration) including the current detection circuit of any one of the first to sixth configurations.

[0079] Although certain embodiments have been described, these embodiments have been presented only by way of example and are not intended to limit the scope of the present disclosure. In fact, the embodiments described herein may be implemented in various other forms. In addition, various omissions, substitutions, and changes may be made to the forms of the embodiments described herein without departing from the spirit of the present disclosure. The attached claims and their equivalents are intended to cover such forms or modifications that will fall within the scope and spirit of the present disclosure.

[0080] Description of Reference Numerals

[0081] 100, 101: Switching power supply device

[0082] 200, 201: Switching power supply controller

[0083] 300, 301: Current detection circuit

[0084] 400: Light emitting device

[0085] 401: Light emitting element driver

[0086] 402: Inductor

[0087] 403: N-channel MOS field effect transistor

[0088] 404: Output capacitor

[0089] 405: Light emitting element

[0090] 406: Current detection circuit

[0091] 500: Motor unit

[0092] 501: Motor driver

[0093] 502: Three-phase inverter

[0094] 503: Three-phase motor

[0095] 504: Current detection circuit

[0096] AMP1: Amplifier

[0097] C0: Output capacitor

[0098] C1, C2: capacitors

[0099] CNT1: Control unit

[0100] COMP1, COMP2: Comparator

[0101] CS0, CS1, CS2: current source

[0102] D1, D2: Driver

[0103] INV1: Inverter

[0104] L1: Inductor

[0105] Q1, Q3, Q4: P-channel MOS field effect transistors

[0106] Q2, Q5, Q6: N-channel MOS field effect transistors

[0107] R0: Sense resistor

[0108] R1, R2: Resistors

[0109] SW1: switch.

Claims

1. A current detection circuit, comprising: a first comparator configured to compare a sense voltage corresponding to a current flowing through the switching element when the switching element is turned on with a threshold voltage; as well as A determiner configured to determine, based on the output of the first comparator, whether a timing at which the magnitude relationship between the sense voltage and the threshold voltage is reversed after the switching element is turned on is before a predetermined time has passed after the switching element is turned on. 2 . The current detection circuit according to claim 1 , wherein the sense voltage is a voltage generated at a connection node between the switching element and an inductor.

3. The current detection circuit according to claim 1, wherein the determiner comprises: a first charger configured to charge with a first constant current until a magnitude relationship between the sense voltage and the threshold voltage is reversed after the switching element is turned on; a second charger configured to charge with a second constant current after the magnitude relationship between the sensing voltage and the threshold voltage is reversed; as well as A second comparator is configured to compare a charging voltage of the first charger with a charging voltage of the second charger.

4. The current detection circuit according to claim 3, wherein the determiner comprises: a first discharger configured to discharge the first charger during a period when the switching element is turned off; as well as a second discharger configured to discharge the second charger during a period from when the switching element is turned on until the magnitude relationship between the sense voltage and the threshold voltage is reversed and during a period when the switching element is turned off.

5. The current detection circuit according to claim 1 , further comprising a voltage generator configured to generate the threshold voltage. The voltage generator comprises: a resistor element, the resistance value of which is greater than the on-resistance of the switch element; as well as A current source is configured to cause a set current to flow through the resistance element. 6 . The current detection circuit according to claim 5 , wherein the switch element and the resistance element are MOS field effect transistors having different ratios of channel width to channel length.

7. A switching power supply controller, comprising the current detection circuit according to any one of claims 1 to 6. 8 . A light emitting element driver, comprising the current detection circuit according to claim 1 .

9. A motor driver comprising the current detection circuit according to any one of claims 1 to 6.

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