Power supply control device and switching power supply device

Abstract

To provide a power supply control device capable of detecting an abnormality of an inductor.SOLUTION: A power supply control device (1) is a power supply control device constructed so as to control a switching power supply device in a switching power supply device (10) having an inductor (L1), and comprises: a switch driving part (7) that is constructed so as to perform control for generating a pulse-like voltage (SW) in which a switching element (Q1) connected to the inductor is in an ON state in order to be a high level for a predetermined time; and an abnormal detection part (6) that is constructed so as to detect a presence / absence of an abnormality of the inductor on the basis of a current (Iq) flowing in the switching element when the pulse-like voltage is generated.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a power supply control device. [Background technology]

[0002] As a conventional switching power supply device, for example, Patent Document 1 discloses a switching power supply device configured with a semiconductor integrated circuit device and external components thereof. The external components include an inductor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-97541

[0004] [overview] Increasing the switching frequency of a switching power supply makes it possible to reduce the inductance value of the inductor. However, if a switching power supply operates with a low inductance value, there is a possibility that the inductor may operate due to parasitic inductance if an abnormality occurs in which the inductor is shorted, and this raises the risk that the inductor abnormality may not be detected.

[0005] In view of the above circumstances, an object of the present disclosure is to provide a power supply control device that is capable of detecting an abnormality in an inductor.

[0006] A power supply control device according to an embodiment of the present disclosure includes: A power supply control device configured to control a switching power supply device having an inductor, the power supply control device comprising: a switch driver configured to perform control to generate a pulsed voltage that is at a high level for a predetermined period of time by turning on a switching element connected to the inductor; an abnormality detection unit configured to detect the presence or absence of an abnormality in the inductor based on a current flowing through the switching element when the pulsed voltage is generated; The configuration is provided with the following. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing a configuration of a switching power supply device according to an exemplary embodiment of the present disclosure. [Diagram 2] FIG. 2 is a timing chart relating to the operation of detecting an abnormality in an inductor. [Diagram 3] FIG. 3 is a diagram illustrating an example of the configuration of the pulse generating unit. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of the reference voltage generating unit. [Diagram 5] FIG. 5 is a diagram showing a configuration of a switching power supply device according to a modified example of the present disclosure.

[0008] [Detailed Description] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.

[0009] <1. Configuration of switching power supply unit> 1 is a diagram showing a configuration of a switching power supply device 10 according to an exemplary embodiment of the present disclosure. The switching power supply device 10 is a synchronous rectification type step-down DC / DC converter that steps down an input voltage Vin, which is a DC voltage, to an output voltage Vout, which is also a DC voltage.

[0010] The switching power supply device 10 includes a power supply control device 1, an inductor L1, an output capacitor C1, and feedback resistors R1 and R2. The inductor L1, the output capacitor C1, and the feedback resistors R1 and R2 are disposed outside the power supply control device 1.

[0011] The power supply control device 1 is a semiconductor device having an integrated circuit that integrates the internal configuration shown in Fig. 1. The power supply control device 1 has an error amplifier 2, a ramp generating unit 3, an adding unit 4, a comparator 5, an overcurrent detecting unit 6, a switch driving unit 7, a pulse generating unit 8, an upper switching element Q1, and a lower switching element Q2.

[0012] The power supply control device 1 also has terminals T1 to T3 as external terminals for establishing electrical connections with the outside.

[0013] The terminal T1 is connected to an application terminal of the input voltage Vin. The upper switching element Q1 and the lower switching element Q2 are connected in series between the terminal T1 and an application terminal of the ground potential. The upper switching element Q1 is configured by a P-channel type MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). The lower switching element Q2 is configured by an N-channel type MOSFET. The source of the upper switching element Q1 is connected to the terminal T1 via the overcurrent detection unit 6. The drain of the upper switching element Q1 is connected to the drain of the lower switching element Q2 at the node Nsw. The source of the lower switching element Q2 is connected to the application terminal of the ground potential.

[0014] The node Nsw is connected to the terminal T2. One end of an inductor L1 is externally connected to the terminal T2. The other end of the inductor L1 is connected to one end of the output capacitor C1. An output voltage Vout is generated at one end of the output capacitor C1. Feedback resistors R1 and R2 are connected in series between the application end of the output voltage Vout and the application end of the ground potential. The node to which the feedback resistors R1 and R2 are connected is connected to the inverting input end (-) of the error amplifier 2 via the terminal T3. A feedback voltage FB obtained by dividing the output voltage Vout by the feedback resistors R1 and R2 is generated at the terminal T3.

[0015] The non-inverting input terminal (+) of the error amplifier 2 is connected to the application terminal of the reference voltage REF. The error amplifier 2 amplifies the difference between the feedback voltage FB and the reference voltage REF and outputs the amplifier output voltage COMP. The amplifier output voltage COMP is input to the non-inverting input terminal (+) of the comparator 5.

[0016] The adder 4 generates a slope signal SLOPE by adding a current detection signal ISENSE that detects the current flowing through the inductor L1 and the ramp signal generated by the ramp generator 3. This performs current mode control. The slope signal SLOPE is input to the inverting input terminal (-) of the comparator 5. The current detection signal ISENSE can be detected by, for example, a current sensor 6B described later, but the detection method is not limited thereto.

[0017] The comparator 5 compares the amplifier output voltage COMP with the slope signal SLOPE, and outputs a reset signal RST as the comparison result. The switch driver 7 drives the upper switching element Q1 and the lower switching element Q2 by outputting a gate signal G1 to the gate of the upper switching element Q1 and a gate signal G2 to the gate of the lower switching element Q2. That is, the switch driver 7 operates as a gate driver. The switch driver 7 complementarily switches the upper switching element Q1 and the lower switching element Q2 based on a set signal and a reset signal RST (not shown). Note that a simultaneous off period (so-called dead time) may be provided during the complementary switching.

[0018] In this way, PWM (pulse width modulation) control is performed by feedback of the output voltage Vout, and the output voltage Vout is controlled to a target value defined by the reference voltage REF and the feedback resistors R1 and R2. The upper switching element Q1 and the lower switching element Q2 may be disposed outside the power supply control device 1. Also, the lower switching element Q2 may be replaced with a diode, and the switching power supply device 10 may be a so-called asynchronous DC / DC converter.

[0019] 2. Inductor abnormality detection When the switching frequency of the switching power supply device 10 is increased, the inductance value of the inductor L1 and the capacitance value of the output capacitor C1 can be reduced, making it possible to save space. However, a parasitic inductance Lp is formed on the board on which the switching power supply device 10 is mounted, as shown in FIG. 1. Even if an abnormality occurs in which the inductor L1 is shorted, the switching power supply device 10 may still operate due to the parasitic inductance Lp. Therefore, the power supply control device 1 of this embodiment is provided with a function for detecting an abnormality in the inductor L1 before starting up the switching power supply device 10.

[0020] In order to detect an abnormality in the inductor L1, the power supply control device 1 is provided with a pulse generating unit 8 and an overcurrent detecting unit 6.

[0021] The pulse generating unit 8 generates a pulse signal Pls with a predetermined pulse width before starting up the switching power supply device 10. Based on the generated pulse signal Pls, the switch driving unit 7 drives the upper switching element Q1 to the ON state (the lower switching element Q2 is in the OFF state) for a predetermined time period corresponding to the above-mentioned predetermined pulse width. This generates a pulsed switch voltage SW that is at a high level (=Vin) at the node Nsw for the above-mentioned predetermined time period. The switch voltage SW is applied to a combined inductance formed by the inductor L1 and the parasitic inductance Lp.

[0022] Before startup, the output voltage Vout is 0 V, and by generating a pulsed switch voltage SW, a current flows through the inductor L1, the output capacitor C1 is charged, and the output voltage Vout rises. Here, the inductance is expressed by the following equation (1). L = v × (dt / di) (1) where L is the inductance value, v is the voltage across the inductor, dt is the change in time, and di is the change in current flowing through the inductor.

[0023] v is the voltage across the inductor, but the time during which the switch voltage SW is at high level is short, and the output voltage Vout hardly fluctuates compared to the input voltage Vin, so v = Vin can be set. If dt is the above-mentioned predetermined time during which the switch voltage SW is at high level, and the amount of change in the current Iq flowing through the upper switching element Q1 when a pulsed switch voltage SW is generated is defined as di, then the inductance value can be found by measuring di. Note that when the inductor L1 is normal, the current Iq flows through the inductor L1 and the parasitic inductance Lp, but when an abnormality such as a short circuit occurs in the inductor L1, it does not flow through the inductor L1, but only through the parasitic inductance Lp.

[0024] The overcurrent detection unit 6 monitors the current Iq flowing through the upper switching element Q1 when a pulsed switch voltage SW is generated. The overcurrent detection unit 6 includes a comparator 6A and a current sensor 6B. A reference voltage Vref that is lower than the input voltage Vin by a predetermined voltage ΔV is applied to the non-inverting input terminal (+) of the comparator 6A. The current sensor 6B is configured, for example, by a current detection resistor, and performs current / voltage conversion on the current Iq to generate a current detection signal Isns. The current detection signal Isns is applied to the inverting input terminal (-) of the comparator 6A. The comparator 6A compares the reference voltage Vref with the current detection signal Isns, and outputs a detection signal DET as a comparison result. When the current Iq exceeds the overcurrent detection level, the current detection signal Isns falls below the reference voltage Vref, and the detection signal DET switches from a low level to a high level. That is, the reference voltage Vref defines the above-mentioned overcurrent detection level.

[0025] Figure 2 is a timing chart related to the inductor abnormality detection operation. In Figure 2, the left side shows an example of operation when inductor L1 is normal, and the right side shows an example of operation when a short abnormality occurs in inductor L1. In Figure 2, from the top to the bottom, the switch voltage SW, current Iq, and detection signal DET are shown.

[0026] At time t1 in Figure 2, the switch voltage SW rises to a high level, and the current Iq starts to increase from 0 A. When the inductor L1 is normal (left side of Figure 2), at time t2, a predetermined time dt after time t1 when the switch voltage SW reaches a high level, the current Iq reaches a current value that has changed from 0 A by di when L = the combined inductance of inductor L1 and parasitic inductance Lp in the above equation (1). Because the overcurrent detection level OC is set higher than the current value at this time, the current Iq cannot reach the overcurrent detection level OC at time t2, and the detection signal DET remains at a low level.

[0027] On the other hand, when inductor L1 is short-circuited (on the right side of Figure 2), at time t2, current Iq reaches a current value that has changed from 0A by di when L = parasitic inductance Lp in equation (1) above. At this time, di is larger than when inductor L1 is normal. At this time, the current value that current Iq reaches exceeds overcurrent detection level OC, so the detection signal DET goes high. Therefore, it is possible to detect whether or not there is an abnormality in the inductance value of inductor L1 based on the level of detection signal DET at time t2.

[0028] When the switch driver 7 determines that an abnormality has occurred in the inductor L1 based on the level of the detection signal DET, the switch driver 7 does not start up the switching power supply device 10. Note that the switch driver 7 may detect the abnormality of the inductor L1 by detecting that the detection signal DET has switched from a low level to a high level before a predetermined time dt has elapsed (timing t3 in FIG. 2).

[0029] It is preferable that the predetermined time dt during which the switch voltage SW is at a high level is set so that the rising output voltage Vout does not reach a UVLO (Under Voltage Lock Out) release voltage in the subsequent circuit 100 (FIG. 1) to which the output voltage Vout is supplied. This makes it possible to prevent the UVLO in the subsequent circuit 100 from being released before the switching power supply device 10 is started.

[0030] In addition, an abnormality in inductor L1 may be detected by measuring the current value reached by current Iq at timing t2 after a predetermined time dt has elapsed, and calculating the inductance value from the above equation (1) based on the measured current value and dt.

[0031] Furthermore, a switching element other than the high-side switching element Q1 may be connected in parallel to the high-side switching element Q1, and when detecting an abnormality in the inductor L1, the high-side switching element Q1 may be in an off state and the other switching element may be switched to generate a pulsed switch voltage SW. In other words, a switching element other than the high-side switching element Q1 used for step-down operation during normal operation may be used for abnormality detection.

[0032] <3. Variable pulse width> When the input voltage Vin is fixed, dt, i.e., the predetermined pulse width of the pulse signal Pls, can be fixed according to the above formula (1). However, when the input voltage Vin is variable, the predetermined pulse width of the pulse signal Pls must also be variable. Figure 3 shows an example of the configuration of the pulse generating unit 8 that makes the predetermined pulse width variable according to the input voltage Vin in this way.

[0033] The pulse generating unit 8 shown in FIG. 3 includes voltage dividing resistors 81 and 82, an amplifier 83, a transistor 84, a V / I conversion resistor 85, a current mirror 86, a capacitor 87, a switch 88, and a comparator 89.

[0034] The voltage dividing resistors 81 and 82 divide the input voltage Vin. The voltage Vdv obtained by the voltage division is applied to the non-inverting input terminal of the amplifier 83. The output terminal of the amplifier 83 is connected to the gate of a transistor 84 configured by an N-channel MOSFET. The source of the transistor 84 is connected to one terminal of a V / I conversion resistor 85 and the inverting input terminal of the error amplifier 83. The current mirror 86 is configured by a P-channel MOSFET. The drain of the transistor 84 is connected to the input terminal of the current mirror 86. The output terminal of the current mirror 86 is connected to one terminal of a capacitor 87. A switch 88 is connected between both ends of the capacitor 87. The voltage of the capacitor 87 is applied to the inverting input terminal of a comparator 89. A reference voltage V89 is applied to the non-inverting input terminal of the comparator 89. A pulse signal Pls is output from the comparator 89, which compares the voltage of the capacitor 87 with the reference voltage V89.

[0035] With this configuration, the source of the transistor 84 is controlled to have a voltage Vdv, and the voltage Vdv is converted to a current I1 by the V / I conversion resistor 85. The current I1 is mirrored by the current mirror 86 to become a current I2.

[0036] When the pulse signal Pls is generated, the switch 88 is turned on by the trigger signal Trig, and the capacitor 87 is discharged. Then, the voltage of the capacitor 87 becomes 0V, and the pulse signal Pls rises from low level to high level. Then, the switch 88 is turned off by the trigger signal Trig, and charging of the capacitor 87 with the current I2 begins. When the voltage of the capacitor 87 rises due to charging and exceeds the reference voltage V89, the pulse signal Pls falls to low level.

[0037] If the resistance values ​​of the voltage dividing resistors 81 and 82 are equal, the predetermined pulse width W of the pulse signal Pls thus generated is expressed by the following equation (2). W = (C87 × V89 × R85 × 2) / Vin (2) where C87 is the capacitance of capacitor 87, and R85 is the resistance of V / I conversion resistor 85.

[0038] Therefore, the predetermined pulse width W has a characteristic that is inversely proportional to the input voltage Vin. As a result, in the above formula (1), the change in the input voltage Vin can be offset by the change in the predetermined pulse width W, that is, dt.

[0039] <4. Variable overcurrent detection level> When the input voltage Vin is fixed, if dt is fixed according to the above formula (1), the overcurrent detection level may be fixed. However, when the input voltage Vin is variable, if dt is fixed, the overcurrent detection level must also be variable. Figure 4 shows an example of the configuration of the reference voltage generating unit 9 that makes the overcurrent detection level variable according to the input voltage Vin in this way.

[0040] The reference voltage generating unit 9 includes voltage dividing resistors 91 and 92 , an amplifier 93 , a transistor 94 , a V / I conversion resistor 95 , and an I / V conversion resistor 96 .

[0041] The voltage dividing resistors 91 and 92 divide the input voltage Vin. The voltage Vdv2 obtained by the voltage division is applied to the non-inverting input terminal of the amplifier 93. The output terminal of the amplifier 93 is connected to the gate of a transistor 94 configured by an N-channel MOSFET. The source of the transistor 94 is connected to one terminal of a V / I conversion resistor 95 and the inverting input terminal of the error amplifier 93. The drain of the transistor 94 is connected to one terminal of an I / V conversion resistor 96. The other terminal of the I / V conversion resistor 96 is connected to the application terminal of the input voltage Vin.

[0042] With this configuration, the source of the transistor 94 is controlled to have a voltage Vdv2, and the voltage Vdv2 is converted to a current Ia by the V / I conversion resistor 95. The current Ia is current / voltage converted by the I / V conversion resistor 96 to become ΔV. A reference voltage Vref=Vin-ΔV is generated at one end of the I / V conversion resistor 96.

[0043] If the resistance values ​​of the voltage dividing resistors 91 and 92 are equal, the reference voltage Vref is expressed by the following equation (3). Vref=Vin-ΔV=Vin×(1-R96 / (2×R95)) Where R96 is the resistance of I / V conversion resistor 96, and R95 is the resistance of V / I conversion resistor 95.

[0044] Therefore, the reference voltage Vref, i.e., the overcurrent detection level, has a characteristic that is proportional to the input voltage Vin. As a result, in the above formula (1), the change in the input voltage Vin can be offset by the change in the overcurrent detection level.

[0045] <5. Modifications> 5 is a diagram showing a configuration of a switching power supply device 20 according to a modified example of the present disclosure. The switching power supply device 20 is configured as a step-up DC / DC. The switching power supply device 20 has a power supply control device 11, an inductor L1, a diode D1, and an output capacitor C1. The inductor L1, the diode D1, and the output capacitor C1 are disposed outside the power supply control device 11.

[0046] The power supply control device 11 has, integrated therein, a switch driving section 12, a switching element 13, a protection switch 14, an overcurrent detection section 15, and a pulse generation section 16. The power supply control device 11 also has terminals T11 to T15 as external terminals.

[0047] An application terminal of the input voltage Vin is connected to a terminal T12. The protection switch 14 is formed of a P-channel MOSFET 14. The terminal T12 is connected to a source of the protection switch 14. The drain of the protection switch 14 is connected to a terminal T13. The terminal T13 is connected to one end of an inductor L1. The other end of the inductor L1 is connected to a terminal T14.

[0048] The switching element 13 is composed of an N-channel MOSFET. The source of the switching element 13 is connected to a terminal T15. The terminal T15 is connected to a terminal to which a ground potential is applied. A node Nd, to which the terminal T14 and the drain of the switching element 13 are connected, is connected to a terminal T11. The terminal T11 is connected to an anode of a diode D1. The cathode of the diode D1 is connected to one end of an output capacitor C1.

[0049] The switch driver 12 drives the switching element 13. The switch driver 12 also drives the protection switch 14. During normal operation, the protection switch 14 is turned on, and the input voltage Vin is boosted by switching of the switching element 13 to generate the output voltage Vout. The output voltage Vout is generated at one end of the output capacitor C1. Note that, if an overcurrent is detected in the current flowing through the inductor L1 during normal operation, the switch driver 12 turns off the protection switch 14, providing overcurrent protection.

[0050] Similarly to the embodiment described above, the power supply control device 11 is also provided with a function for detecting an abnormality in the inductor L1. For this function, a pulse generating unit 16 and an overcurrent detecting unit 15 are provided in the power supply control device 11. The overcurrent detecting unit 15 is provided between the node Nd and the terminal T11.

[0051] Before starting up the switching power supply device 20, the pulse generating unit 16 generates a pulse signal Pls with a predetermined pulse width. Based on the pulse signal Pls, the switch driving unit 12 turns on the protection switch 14 for a predetermined time period corresponding to the predetermined pulse width, and applies a pulsed voltage of a high level (=Vin) to one end of the inductor L1 for the above-mentioned predetermined time period (the switching element 13 is in an off state).

[0052] At this time, the current flowing through the protection switch 14 is monitored by the overcurrent detection unit 15. An abnormality in the inductance value of the inductor L1 can be detected based on the detection signal DET output from the overcurrent detection unit 15. In this manner, in this embodiment, the protection switch 14 is used to generate a pulsed voltage, making it possible to detect an abnormality in the inductor L1.

[0053] <6.Other> In addition to the above-mentioned embodiment, various technical features disclosed in this specification can be modified in various ways without departing from the spirit of the technical creation. In other words, the above-mentioned embodiment should be considered to be illustrative and not restrictive in all respects, and the technical scope of the present invention should not be limited to the above-mentioned embodiment, but should be understood to include all modifications that fall within the meaning and scope equivalent to the scope of the claims.

[0054] <7. Notes> As described above, the power supply control device (1) according to one embodiment of the present disclosure has: A power supply control device configured to control a switching power supply device (10) having an inductor (L1), a switch driver (7) configured to perform control to generate a pulsed voltage (SW) that is at a high level for a predetermined period of time by turning on a switching element (Q1) connected to the inductor; an abnormality detection unit (6) configured to detect the presence or absence of an abnormality in the inductor based on a current (Iq) flowing through the switching element when the pulsed voltage is generated; The first configuration includes the above.

[0055] In the first configuration, the abnormality detection unit (6) is configured to detect an overcurrent of a current flowing through the switching element, The abnormality detection unit may be configured to detect the presence or absence of the abnormality based on whether or not the current flowing through the switching element reaches an overcurrent detection level when the predetermined time has elapsed (second configuration).

[0056] In the second configuration, the high level is a level of an input voltage (Vin) of the switching power supply device, The predetermined time may be variable depending on the input voltage (third configuration).

[0057] In the third configuration, the device further includes a pulse generating unit (8) configured to generate a pulse signal (Pls), The switch driver generates the pulsed voltage based on the pulse signal, The pulse generating section may be configured to vary the pulse width of the pulse signal in response to the input voltage (fourth configuration).

[0058] In the fourth configuration, the pulse generating unit (8) a first voltage dividing resistor (81, 82) that divides the input voltage (Vin) to generate a first divided voltage (Vdv); a first amplifier (83) having a first input terminal to which the first divided voltage is applied; a first transistor (84) having a control terminal connected to the output terminal of the first amplifier; a first V / I conversion resistor (85) connected to a first terminal of the first transistor and a second input terminal of the first amplifier; a current mirror (86) having an input terminal connected to the second terminal of the first transistor; a first capacitor (87) connected to the output terminal of the current mirror; a switch (88) connected across the first capacitor; a first comparator (89) to which the voltage of the first capacitor and a first reference voltage (V89) are input; having The pulse signal may be output from the first comparator (fifth configuration).

[0059] In the second configuration, the high level is a level of an input voltage of the switching power supply device, The overcurrent detection level may be variable depending on the input voltage (sixth configuration).

[0060] In the sixth configuration, the abnormality detection unit (6) has a second comparator (6A) that compares a detection signal (Isns) of a current flowing through the switching element with a second reference voltage (Vref), The second reference voltage may be variable depending on the input voltage (seventh configuration).

[0061] In the seventh configuration, the power supply device further includes a reference voltage generating unit (9) configured to generate the second reference voltage (Vref), The reference voltage generating unit is A second voltage dividing resistor (91.92) that divides the input voltage (Vin) to generate a second divided voltage (Vdv2); a second amplifier (93) having a first input terminal to which the second divided voltage is applied; a second transistor (94) having a control terminal connected to the output terminal of the second amplifier; a second V / I conversion resistor (95) connected to the first terminal of the second transistor and the second input terminal of the second amplifier; an I / V conversion resistor (96) having a first terminal connected to the second terminal of the second transistor and a second terminal connected to the input voltage application terminal; having The second reference voltage may be generated at a first end of the I / V conversion resistor (eighth configuration).

[0062] In any one of the first to eighth configurations, the generation of the pulsed voltage may be performed before the switching power supply device is started up (ninth configuration).

[0063] In addition, in any of the first to ninth configurations, the predetermined time may be set so that the output voltage (Vout) of the switching power supply device does not reach a UVLO release voltage of a subsequent circuit (100) configured to be supplied with the output voltage (Vout) (tenth configuration).

[0064] In addition, in any one of the first to tenth configurations, the switching power supply device (10) is configured as a step-down DC / DC converter, The switching element (Q1) is a high-side switching element connected between an application terminal of an input voltage (Vin) and a first terminal of the inductor (L1), The upper switching element may be used to step down the input voltage (eleventh configuration).

[0065] In any one of the first to tenth configurations, the switching power supply device (20) is configured as a step-up DC / DC converter, The switching element (14) may be a protection switch connected between an application terminal of an input voltage (Vin) and the first terminal of the inductor (L1) (twelfth configuration).

[0066] Furthermore, a switching power supply device (10) according to an embodiment of the present disclosure includes a power supply control device (1) having any one of the first to twelfth configurations described above, the switching element (Q1), and the inductor (L1) (thirteenth configuration). [Industrial Applicability]

[0067] The present disclosure can be used in switching power supply devices for various applications. [Explanation of symbols]

[0068] 1 Power supply control device 2 Error Amplifier 3. Ramp Generation Section 4 Addition section 5. Comparator 6 Overcurrent detection section 6A Comparator 6B Current Sensor 7 Switch drive unit 8 Pulse Generation Section 9 Reference voltage generator 10. Switching power supply 11 Power supply control device 12 Switch drive unit 13 Switching elements 14 Protection Switch 15 Overcurrent detection section 16 Pulse Generation Section 20 Switching power supply unit 81,82 Voltage divider resistor 83 Amplifier 84 Transistors 85 V / I conversion resistor 86 Current Mirror 87 Capacitor 88 Switch 89 Comparator 91,92 Voltage divider resistor 93 Amplifier 94 Transistor 95 V / I conversion resistor 96 I / V conversion resistor 100 Rear circuit C1 Output capacitor D1 Diode L1 Inductor Lp Parasitic inductance Q1 Upper switching element Q2 Lower switching element R1, R2 Feedback resistors T1~T3, T11~T15 terminals

Claims

1. A power supply control device configured to control a switching power supply device having an inductor, the power supply control device comprising: a switch driver configured to perform control to generate a pulsed voltage that is at a high level for a predetermined period of time by turning on a switching element connected to the inductor; an abnormality detection unit configured to detect the presence or absence of an abnormality in the inductor based on a current flowing through the switching element when the pulsed voltage is generated; A power supply control device comprising:

2. the abnormality detection unit is configured to detect an overcurrent of a current flowing through the switching element, 2 . The power supply control device according to claim 1 , wherein the abnormality detection unit detects the presence or absence of the abnormality based on whether or not a current flowing through the switching element has reached an overcurrent detection level when the predetermined time has elapsed.

3. the high level is a level of an input voltage of the switching power supply device, 3. The power supply control device according to claim 2, wherein the predetermined time is variable depending on the input voltage.

4. a pulse generator configured to generate a pulse signal; The switch driver generates the pulsed voltage based on the pulse signal, The power supply control device according to claim 3 , wherein the pulse generating section varies a pulse width of the pulse signal in response to the input voltage.

5. The pulse generating unit is a first voltage dividing resistor that divides the input voltage to generate a first divided voltage; a first amplifier having a first input terminal to which the first divided voltage is applied; a first transistor having a control terminal connected to an output terminal of the first amplifier; a first V / I conversion resistor connected to a first terminal of the first transistor and a second input terminal of the first amplifier; a current mirror having an input terminal connected to the second terminal of the first transistor; A first capacitor connected to an output terminal of the current mirror; a switch connected across the first capacitor; a first comparator to which the voltage of the first capacitor and a first reference voltage are input; having The power supply control device according to claim 4 , wherein the pulse signal is output from the first comparator.

6. the high level is a level of an input voltage of the switching power supply device, 3. The power supply control device according to claim 2, wherein the overcurrent detection level is variable depending on the input voltage.

7. the abnormality detection unit has a second comparator that compares a detection signal of a current flowing through the switching element with a second reference voltage; 7. The power supply control device according to claim 6, wherein the second reference voltage is variable depending on the input voltage.

8. a reference voltage generating unit configured to generate the second reference voltage; The reference voltage generating unit is a second voltage dividing resistor that divides the input voltage to generate a second divided voltage; a second amplifier having a first input terminal to which the second divided voltage is applied; a second transistor having a control terminal connected to the output terminal of the second amplifier; a second V / I conversion resistor connected to a first terminal of the second transistor and a second input terminal of the second amplifier; an I / V conversion resistor having a first terminal connected to the second terminal of the second transistor and a second terminal connected to an application terminal of the input voltage; having The power supply control device according to claim 7 , wherein the second reference voltage is generated at a first end of the I / V conversion resistor.

9. 2. The power supply control device according to claim 1, wherein the pulsed voltage is generated before start-up of the switching power supply device.

10. 2. The power supply control device according to claim 1, wherein the predetermined time is set so that the output voltage of the switching power supply device does not reach a UVLO release voltage of a subsequent circuit configured to be supplied with the output voltage of the switching power supply device.

11. the switching power supply device is configured as a step-down DC / DC converter, the switching element is an upper switching element connected between an input voltage application terminal and a first terminal of the inductor, The power supply control device according to claim 1 , wherein the high-side switching element is used to step down the input voltage.

12. The switching power supply device is configured as a step-up DC / DC converter, 2. The power supply control device according to claim 1, wherein the switching element is a protection switch connected between an input voltage application terminal and a first terminal of the inductor.

13. A switching power supply device comprising: the power supply control device according to claim 1 ; the switching element; and the inductor.

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