Power supply device

Abstract

A power supply device according to one embodiment of the present disclosure includes: a power supply IC including a switching circuit that switches at a ratio matching circuit characteristics on an output side and has a pair of switching elements connecting an output node to a primary power supply voltage or a ground, and an internal control circuit that controls the switching circuit; the power supply IC includes an internal input terminal to which a primary power supply voltage is inputted, an internal output terminal to which a rectangular wave voltage outputted from the switching element is outputted, a tracking terminal to which a tracking voltage setting a voltage value of the output voltage is inputted, and a feedback terminal to which a feedback voltage indicating an actual voltage value of the output voltage is inputted. An output inductor, one end of which is connected to the internal output terminal; an output capacitor connected to the other end of the output inductor; a tracking ground circuit capable of grounding the tracking terminal; and a tracking control circuit that controls the tracking ground circuit.

Description

Technical Field

[0001] This invention relates to power supply devices. Background Technology

[0002] A power supply IC that steps down a primary power supply voltage to a set voltage and outputs it is being utilized. As an example, a DC / DC converter is known to include a power supply IC having a high-side switching element that applies a primary power supply voltage to the output node and a low-side switching element that grounds the output node. The DC / DC converter switches the high-side and low-side switching elements according to the difference between the set voltage and the output voltage. Additionally, typically, an inductor (coil) and a capacitor (capacitor) charged via the inductor are connected to the output of the power supply IC. In this case, the output voltage of the capacitor is fed back to the power supply IC, and the high-side and low-side switching elements are controlled to maintain the output voltage of the capacitor at the set voltage (see, for example, Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-78203 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the aforementioned DC / DC converter, even if the output of the power supply IC is stopped, the output voltage will not decrease unless the charge in the capacitor is consumed by the load. Depending on the overall device structure including the load, it is sometimes necessary to rapidly reduce the output voltage when the primary power supply voltage to the power supply device is cut off.

[0008] Methods for solving problems

[0009] One aspect of the power supply device disclosed herein includes: a power supply IC comprising a switching circuit and an internal control circuit for controlling the switching circuit, the switching circuit switching at a ratio matching the circuit characteristics of the output side and having a pair of switching elements connecting an output node to a primary power supply voltage or ground; the power supply IC having an internal input terminal for receiving a primary power supply voltage, an internal output terminal for outputting a rectangular wave voltage from the switching elements, a tracking terminal for receiving a tracking voltage value for setting the output voltage, and a feedback terminal for receiving a feedback voltage representing the actual output voltage value; an output inductor connected to the internal output terminal; an output capacitor connected to the output inductor; a tracking grounding circuit capable of grounding the tracking terminal; and a tracking control circuit for controlling the tracking grounding circuit. Attached Figure Description

[0010] Figure 1 This is a circuit diagram of a power supply device according to the first embodiment of this disclosure.

[0011] Figure 2 This is a circuit diagram of a power supply device according to a second embodiment of the present disclosure.

[0012] Figure 3 This is a circuit diagram of a power supply device according to a third embodiment of this disclosure. Detailed Implementation

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Furthermore, in the following various embodiments, the same reference numerals are sometimes used to denote the same constituent elements, and repeated descriptions are omitted.

[0014] [First Implementation Method]

[0015] Figure 1 This is a circuit diagram of a power supply device 1 according to the first embodiment of this disclosure. The power supply device 1 includes a power supply IC 10, an output inductor 21, an output capacitor 22, an output feedback circuit 30, a tracking ground circuit 40, and a tracking control circuit 50. Furthermore, the power supply device 1 has an input terminal 61 for receiving a primary power supply voltage (input voltage) Vin, an output terminal 62 for outputting an output voltage Vout, and a setting terminal 63 for receiving a tracking voltage Vtr for setting the voltage value of the output voltage Vout.

[0016] The power supply IC 10 includes a switching circuit 11 and an internal control circuit 12 that controls the switching circuit 11. Additionally, the power supply IC 10 has an internal input terminal 13 for receiving a primary power supply voltage Vin, an internal output terminal 14 for outputting a rectangular wave voltage Vvr from the switching circuit 11, a tracking terminal 15 for receiving a tracking voltage Vtr to set the output voltage Vout, and a feedback terminal 16 for receiving a feedback voltage Vfb to represent the actual output voltage Vout.

[0017] The switching circuit 11 can be a known structure, having: a high-side transistor 111 and its gate driver 112 that applies a primary power supply voltage Vin to the internal output terminal 14 (output node); a low-side transistor 113 and its gate driver 114 that grounds the internal output terminal 14; and a converter controller 115 that inputs a drive signal to the high-side transistor 111 and the low-side transistor 113 to switch the switching state at a ratio matching the circuit characteristics of the output side.

[0018] The internal control circuit 12 can, for example, be configured to include: a reference voltage circuit 121 that generates a reference voltage Vref based on the primary power supply voltage Vin; and a differential amplifier circuit 122 that generates a differential voltage Vdf (Vtr-Vfb) between the lower of the tracking voltage Vtr and the reference voltage Vref and the feedback voltage Vfb, where the tracking voltage Vtr does not exceed the reference voltage Vref. Furthermore, the reference voltage Vref is typically used to determine the final control voltage, but can be omitted if control continues using the input voltage of Vtr as the reference voltage.

[0019] Output inductor 21 is connected to internal output terminal 14 at one end and output capacitor 22 at the other end. Output inductor 21 and output capacitor 22 are known structures for smoothing the rectangular wave voltage output by the operation of high-side transistor 111 and low-side transistor 113. By connecting output inductor 21 and output capacitor 22 to switching circuit 11, a synchronous rectification DC / DC converter capable of generating an output voltage Vout with a desired voltage value based on primary supply voltage Vin is formed.

[0020] The output feedback circuit 30 generates a feedback voltage Vfb representing the voltage value of the output voltage Vout by dividing the output voltage Vout, and inputs it to the feedback terminal 16 of the power supply IC 10.

[0021] The tracking grounding circuit 40 is configured to ground the tracking terminal 15. That is, by releasing the current input from the setting terminal 63 to the ground wire, the tracking grounding circuit 40 causes the tracking voltage Vtr to immediately drop to the ground level. As a result, the differential voltage Vdf output by the differential amplifier circuit 122 decreases, and the switching circuit 11 operates by withdrawing the charge charged into the output capacitor 22. This operation of the switching circuit 11 constitutes a boost operation from the output voltage Vout to the primary power supply voltage Vin, thus enabling power regeneration on the primary power supply side. Therefore, by grounding the tracking terminal 15 through the tracking grounding circuit 40, the power supply unit 1 rapidly reduces the output voltage Vout to the ground level.

[0022] The tracking ground circuit 40 in this embodiment is an open-collector output circuit. Specifically, the tracking ground circuit 40 may have, for example, a field-effect transistor 41. The drain (collector) of the transistor 41 is connected to the tracking terminal 15, and the source (emitter) of the transistor 41 is grounded. A drive signal is input from the tracking control circuit 50 to the gate (base) of the transistor 41. A limiting resistor 631 is provided between the setting terminal 63 and the tracking terminal 15. The tracking ground circuit 40 can be connected to the downstream side of the limiting resistor 631 so that the transistor 41 can operate with a relatively small current.

[0023] The tracking control circuit 50 outputs a control signal to control the tracking ground circuit 40, which turns the gate voltage of transistor 41 on and off. The tracking control circuit 50 is configured to supply gate current when the primary power supply voltage Vin decreases, causing transistor 41 to turn off. As a specific example, the tracking control circuit 50 can be a logic circuit that inverts the voltage monitoring signal of the primary power supply voltage Vin.

[0024] As described above, the power supply unit 1 grounds the tracking terminal 15, which has almost no capacitance, through the tracking grounding circuit 40, thereby causing the output capacitor 22 to discharge rapidly. Therefore, the power supply unit 1 rapidly reduces the output voltage Vout when the primary power supply voltage Vin is cut off.

[0025] [Second Implementation]

[0026] Figure 2 This is a circuit diagram of the power supply device 1A according to the second embodiment of this disclosure. The power supply device 1A includes a power supply IC 10A, an output inductor 21, an output capacitor 22, an output feedback circuit 30, a tracking voltage generation circuit 70, a tracking ground circuit 40A, and a tracking control circuit 50A. Furthermore, the power supply device 1A has an input terminal 61 for receiving a primary power supply voltage Vin, an output terminal 62 for outputting an output voltage Vout, and a setting terminal 63 for receiving a tracking voltage Vtr for setting the voltage value of the output voltage Vout.

[0027] The power IC 10A includes a switching circuit 11 and an internal control circuit 12A that controls the switching circuit 11. Additionally, the power IC 10A has an internal input terminal 13, an internal output terminal 14, a tracking terminal 15, a feedback terminal 16, and a soft-start terminal 17.

[0028] The internal control circuit 12A can be configured to include: a reference voltage circuit 121 that generates a reference voltage Vref; a soft-start circuit 123 that generates a soft-start voltage Vss that rises slowly when a primary power supply voltage Vin is input to the power supply IC 10A; and a differential amplifier circuit 122 that generates a differential voltage Vdf between the lower of the tracking voltage Vtr and the soft-start voltage Vss (within a range not exceeding the reference voltage Vref) and the feedback voltage Vfb.

[0029] The soft-start circuit 123 includes a constant current circuit 1231 that outputs a constant charging current when a primary power supply voltage Vin is input. It is connected to a soft-start capacitor 171, which is charged by the charging current, via a soft-start terminal 17, generating a soft-start voltage Vss as the terminal voltage of the soft-start capacitor 171. The constant current circuit 1231 can be configured to adjust the current supplied from the reference voltage circuit 121.

[0030] The tracking voltage generation circuit 70 is connected to the tracking terminal 15 to generate the tracking voltage Vtr. Specifically, the tracking voltage generation circuit 70 in this embodiment is configured as a regulator that generates the tracking voltage Vtr based on the primary power supply voltage Vin, and the tracking voltage Vtr is determined by its resistance value.

[0031] The tracking grounding circuit 40A in this embodiment is a push-pull output circuit that connects the output to ground or a predetermined potential. Such a tracking grounding circuit 40A can be constructed, for example, using an IC that uses CMOS as the output interface, and therefore can be implemented relatively inexpensively. The tracking grounding circuit 40A in this embodiment is connected to the tracking terminal 15 via a limiting diode 42. The limiting diode 42 prevents the tracking voltage Vtr from rising due to the current output from the tracking grounding circuit 40A. Therefore, by providing the limiting diode 42, the options for the IC used in the tracking grounding circuit 40A can be increased.

[0032] The tracking control circuit 50A can be composed of other components of the IC constituting the tracking ground circuit 40A. This makes the power supply unit 1A relatively inexpensive. In the power supply unit 1A configured to input the tracking voltage Vtr and the soft-start voltage Vss to the differential amplifier circuit 122, the tracking control circuit 50A can, for example, stop the output of the output voltage Vout when the input of the primary power supply voltage Vin is cut off, or when an abnormal signal is input, or after a certain period of time following the stopping of the output of the constant current circuit 1231, ground the tracking terminal 15 through the tracking ground circuit 40A. Thus, after the output stop processing begins, the output voltage Vout is reduced according to the soft-start voltage Vss, thereby suppressing the inrush current from the output capacitor 22 to the switching circuit 11 of the power supply IC 10A. At a certain timing of the discharge of the soft-start capacitor 171, the tracking voltage Vtr is reduced to the ground level, thereby quickly completing the discharge of the output capacitor 22.

[0033] In the power supply device 1A of this embodiment, since it is equipped with a power supply IC 10A having a soft-start circuit 123, it is able to suppress the rise rate of the output voltage Vout and prevent excessive inrush current. In addition, when the output voltage Vout drops, the power supply device 1A uses the tracking grounding circuit 40A to drop the tracking voltage Vtr to the ground level, causing the output voltage Vout to drop rapidly.

[0034] [Third Implementation Method]

[0035] Figure 3 This is a circuit diagram of the power supply device 1B according to the third embodiment of the present disclosure. The power supply device 1B includes a power supply IC 10B, an output inductor 21, an output capacitor 22, an output feedback circuit 30, a tracking voltage generation circuit 70B, a tracking grounding circuit 40, and a tracking control circuit 50.

[0036] The power supply IC10B can be configured to include: a reference voltage circuit 121 that generates a reference voltage Vref; a differential amplifier circuit 122 that generates a differential voltage Vdf between the tracking voltage Vtr and the feedback voltage Vfb; and a constant current circuit 124 that outputs a constant charging current to the tracking terminal 15 when a primary power supply voltage Vin is input to the power supply IC10B.

[0037] The tracking voltage generation circuit 70B has a soft-start capacitor 71 connected to the tracking terminal 15 and charged by the charging current output from the constant current circuit 124, thereby generating the terminal voltage as the tracking voltage Vtr.

[0038] In this embodiment, the tracking ground circuit 40 grounds the tracking terminal 15 via an adjusting resistor 43. The adjusting resistor 43 reduces the rate of decrease of the tracking voltage Vtr and protects the power supply IC 10 from the effects of discharge current. In this embodiment, the tracking ground circuit 40 is connected to the tracking terminal 15 via the adjusting resistor 43, but the source of the transistor 41 can also be grounded via the adjusting resistor 43.

[0039] In the power supply device 1B of this embodiment, the rise and fall of the tracking voltage Vtr are achieved by charging and discharging the soft-start capacitor 71. The decrease in tracking voltage Vtr caused by the discharge of the soft-start capacitor 71 occurs relatively slowly due to the current consumption of the differential amplifier circuit 122 without the tracking ground circuit 40. However, by grounding the output terminal of the soft-start capacitor 71 using the tracking ground circuit 40, it can be achieved quickly. In the power supply device 1B of this embodiment, the tracking control circuit 50 can also activate the tracking ground circuit 40 through appropriate triggering, such as a decrease in the primary power supply voltage Vin, a decrease in a voltage different from Vin, or an abnormal system state, thereby grounding the tracking terminal 15 via the adjusting resistor 43 and adjusting the discharge current.

[0040] The following notes further disclose the above-described embodiments and variations.

[0041] (Note 1)

[0042] Power supply devices 1, 1A, and 1B include: power supply ICs 10, 10A, and 10B, which include a switching circuit 11 and internal control circuits 12, 12A, and 12B controlling the switching circuit 11. The switching circuit 11 switches at a ratio matching the circuit characteristics of the output side and has a pair of switching elements 111 and 113 connecting the output node to the primary power supply voltage or ground. The power supply ICs 10, 10A, and 10B have an internal input terminal 13 for receiving the primary power supply voltage, an internal output terminal 14 for outputting a rectangular wave voltage from the switching elements, a tracking terminal 15 for receiving a tracking voltage value that sets the output voltage, and a feedback terminal 16 for receiving a feedback voltage value that represents the actual output voltage; an output inductor 21, one end of which is connected to the internal output terminal 14; an output capacitor 22, which is connected to the other end of the inductor 21; tracking grounding circuits 40 and 40A, which can ground the tracking terminal 15; and tracking control circuits 50 and 50A, which control the tracking grounding circuits 40 and 40A.

[0043] (Note 2)

[0044] Alternatively, in the power supply device 1A of Appendix 1, the internal control circuit 12A may include: a soft-start circuit 123, which includes a constant current circuit 1231 that outputs a constant charging current, the soft-start circuit 123 being connected to a soft-start capacitor 171 that is charged by the charging current, generating a terminal voltage of the soft-start capacitor 171, i.e., a soft-start voltage; and a differential amplifier circuit 122, which generates a differential voltage between the lower of the tracking voltage and the soft-start voltage and the feedback voltage.

[0045] (Note 3)

[0046] Alternatively, the power supply device 1B in Appendix 1 may also include: a tracking voltage generation circuit 70B connected to the tracking terminal 15 to generate a tracking voltage; an internal control circuit 12B having a constant current circuit 124 that outputs a constant charging current when a primary power supply voltage is input; and a tracking voltage generation circuit 70B having a soft-start capacitor 71 that generates a terminal voltage as the tracking voltage by being charged by the charging current.

[0047] (Note 4)

[0048] Alternatively, in the power supply devices 1A and 1B of Appendix 2 or 3, when the tracking control circuits 50 and 50A stop outputting the output voltage, after a certain period of time following the stop of the output of the constant current circuits 1231 and 124, the tracking terminal 15 is grounded through the tracking grounding circuits 40 and 40A.

[0049] (Note 5)

[0050] Alternatively, in any of the power supply devices 1 and 1B in notes 1 to 4, the tracking grounding circuit 40 is an open-collector output circuit.

[0051] (Note 6)

[0052] Alternatively, in the power supply device 1B of Appendix 5, the tracking grounding circuit grounds the tracking terminal 15 via a resistor.

[0053] (Note 7)

[0054] Alternatively, in any of the power supply devices 1A in notes 1 to 4, the tracking ground circuit 40A is a push-pull output circuit.

[0055] (Postscript 8)

[0056] Alternatively, in the power supply device 1A of Appendix 7, the tracking ground circuit 40A is connected to the tracking terminal 15 via diode 42.

[0057] (Note 9)

[0058] Alternatively, in the power supply device described in Appendix 7, the tracking grounding circuit is connected to the tracking terminal via a resistor.

[0059] The present disclosure has been described in detail above, but it is not limited to the various embodiments described above. Various additions, substitutions, modifications, and partial deletions can be made to these embodiments without departing from the spirit of the present disclosure, or without departing from the spirit of the present disclosure derived from the content described in the claims and their equivalents. Furthermore, these embodiments can also be implemented in combination.

[0060] As an example, in the power supply devices of various embodiments, the tracking grounding circuit can be either an open-collector circuit or a push-pull output circuit. Therefore, the tracking grounding circuit, which is composed of a circuit with a push-pull output, can also be connected to the tracking terminal of a tracking voltage setting circuit with a soft-start capacitor via an adjusting resistor. Furthermore, when the voltage range of the internal control circuit is equal to the voltage range of the output voltage, the undivided temporary power supply voltage and the output voltage can be used as the reference voltage and feedback voltage, respectively.

[0061] In the power supply device disclosed herein, in addition to a single transistor, a circuit with an open collector output, such as a comparator with a transistor, an optocoupler, or an integrated circuit, can be used as the open collector circuit constituting the tracking ground circuit.

[0062] Explanation of reference numerals in the attached figures

[0063] 1. Power supply devices A and B;

[0064] 10, 10A, 10B power supply ICs;

[0065] 11. Switching circuit;

[0066] 111 High-voltage side transistor;

[0067] 112 and 114 gate drivers;

[0068] 113 low-voltage side transistor;

[0069] 115 converter controller;

[0070] 12. 12A internal control circuit;

[0071] 121 reference voltage circuit;

[0072] 122 differential amplifier circuit;

[0073] 123 Soft Start Circuit;

[0074] 1231, 124 constant current circuits;

[0075] 13 internal input terminals;

[0076] 14 internal output terminals;

[0077] 15 tracking terminals;

[0078] 16 feedback terminals;

[0079] 17 soft start terminals;

[0080] 171 and 71 soft-start capacitors;

[0081] 21 Output Inductors;

[0082] 22 Output capacitors;

[0083] 30 Output feedback circuit;

[0084] 40, 40A tracking grounding circuit;

[0085] 41 transistors;

[0086] 42 limiting diode;

[0087] 43. Adjust the resistor;

[0088] 50A tracking control circuit;

[0089] 61 input terminals;

[0090] 62 output terminals;

[0091] 63 Setting Terminal;

[0092] 631 limiting resistor;

[0093] 70, 70B tracking voltage generation circuit.

Claims

1. A power supply device, characterized in that, have: A power supply IC includes a switching circuit and an internal control circuit that controls the switching circuit. The switching circuit switches at a ratio that matches the circuit characteristics of the output side and has a pair of switching elements that connect the output node to a primary power supply voltage or ground. The power supply IC has an internal input terminal that receives the primary power supply voltage, an internal output terminal that outputs a rectangular wave voltage from the switching elements, a tracking terminal that receives a tracking voltage value for setting the output voltage, and a feedback terminal that receives a feedback voltage value representing the actual output voltage value. The output inductor connected to the internal output terminal; The output capacitor connected to the output inductor; A tracking grounding circuit capable of grounding the tracking terminal; as well as The tracking control circuit that controls the tracking grounding circuit.

2. The power supply device according to claim 1, characterized in that, The internal control circuit has: A soft-start circuit includes a constant current circuit that outputs a constant charging current. The soft-start circuit is connected to a soft-start capacitor that is charged by the charging current, thereby generating the terminal voltage of the soft-start capacitor, i.e., the soft-start voltage. as well as A differential amplifier circuit generates a differential voltage between the lower of the tracking voltage and the soft-start voltage and the feedback voltage.

3. The power supply device according to claim 1, characterized in that, The power supply device further includes: a tracking voltage generation circuit, which is connected to the tracking terminal to generate the tracking voltage. The internal control circuit has a constant current circuit that outputs a constant charging current. The tracking voltage generation circuit has a soft-start capacitor that generates a terminal voltage as the tracking voltage by being charged by the charging current.

4. The power supply device according to claim 2 or 3, characterized in that, When the tracking control circuit stops outputting the output voltage, it grounds the tracking terminal through the tracking grounding circuit after a certain period of time following the shutdown of the constant current circuit.

5. The power supply device according to any one of claims 1 to 4, characterized in that, The tracking grounding circuit is an open collector output circuit.

6. The power supply device according to claim 5, characterized in that, The tracking grounding circuit grounds the tracking terminal via a resistor.

7. The power supply device according to any one of claims 1 to 4, characterized in that, The tracking grounding circuit is a push-pull output circuit.

8. The power supply device according to claim 7, characterized in that, The tracking grounding circuit is connected to the tracking terminal via a diode.

9. The power supply device according to claim 7 or 8, characterized in that, The tracking grounding circuit is connected to the tracking terminal via a resistor.

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