Power supply unit

Abstract

A power supply device according to one aspect of the present disclosure comprises: a power IC with a circuit having a pair of switching elements that are switched in a ratio corresponding to the circuit characteristics of the output side and that connect an output node to a primary supply voltage or to ground, and an internal control circuit that controls the circuit, wherein the power IC has an internal input terminal that accepts the input of the primary supply voltage, an internal output terminal that outputs a square wave voltage output by the switching elements, a tracking terminal that accepts the input of a tracking voltage that determines the voltage value of the output voltage, and a feedback terminal that accepts the input of a feedback voltage that indicates the actual voltage value of the output voltage;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, which can ground the tracking terminal; and a tracking control circuit, which controls the tracking ground circuit.

Description

TECHNICAL AREA

[0001] The present invention relates to a power supply device. BACKGROUND OF THE TECHNOLOGY

[0002] A power IC was used that reduces a primary supply voltage to a specified voltage and outputs the reduced voltage. An example is a DC / DC converter that includes a power IC with a high-voltage switching element that applies a supply voltage to an output node and a low-voltage switching element that connects the output node to ground. The high-voltage and low-voltage switching elements are switched according to a difference between a specified voltage and the output voltage. Generally, an inductor (coil) and a capacitor charged across the inductor are connected to the output of the power IC.In this case, feedback via the output voltage of the capacitor is supplied to the power IC, and the high-voltage switching element and the low-voltage switching element are controlled to maintain the output voltage of the capacitor at the specified voltage (see, for example, patent document 1). Citation list of patent specifications

[0003] Patent specification 1: Japanese unexamined patent application, publication no. 2020-78203 DISCLOSURE OF THE INVENTION Problems to be solved by the invention

[0004] In the DC / DC converter described above, the output voltage does not drop even when the power IC's output is stopped, as long as a load is discharging the capacitor. In some cases, depending on the overall device configuration, including the load, the output voltage must drop immediately when the primary supply voltage is switched off by the power supply unit. Means to solve the problems

[0005] A power supply device according to one aspect of the present disclosure comprises a power IC that connects a circuit with a pair of switching elements that switch with a ratio corresponding to an output-side circuit characteristic and an output node to a primary supply voltage or ground, as well as an internal control circuit that controls the circuit and an internal input terminal to which the primary supply voltage is applied, an output terminal from which a square wave voltage generated by the switching elements is output, a tracking terminal to which a tracking voltage is applied to fix a voltage value of an output voltage, and a feedback terminal to which a feedback voltage is applied that indicates an actual voltage value of the output voltage; an output inductor, one end of which is connected to the output terminal;an output capacitor connected to the other end of the output inductor; a tracking ground circuit that can connect the tracking terminal to ground; and a tracking control circuit that controls the tracking ground circuit. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a circuit diagram of a power supply device according to a first embodiment of the present disclosure; Fig. Figure 2 is a circuit diagram of a power supply device according to a second embodiment of the present disclosure; and Fig. Figure 3 is a circuit diagram of a power supply device according to a third embodiment of the present disclosure. PREFERRED METHOD FOR IMPLEMENTING THE INVENTION

[0006] The following describes embodiments of the present disclosure with reference to the drawings. It should be noted that in the multitude of the following embodiments, similar components are designated with the same reference numerals, and overlapping descriptions thereof may be omitted. [First embodiment]

[0007] Fig. Figure 1 is a circuit diagram of a power supply device 1 according to a first embodiment of the present disclosure. The power supply device 1 comprises a power IC 10, an output inductor 21, an output capacitor 22, an output feedback circuit 30, a tracking circuit 40, and a tracking control circuit 50. Furthermore, the power supply device 1 has an input terminal 61 to which a primary supply voltage (input voltage) Vin is applied, an output terminal 62 to which an output voltage Vout is output, and an adjustment terminal 63 to which a tracking voltage Vtr is applied to determine the voltage value of the output voltage Vout.

[0008] The power IC 10 comprises a circuit 11 and an internal control circuit 12 that controls the circuit 11. Furthermore, the power IC 10 has an internal input terminal 13 to which the primary supply voltage Vin is applied, an internal output terminal 14 to which a square wave voltage Vvr output by the circuit 11 is output, a tracking terminal 15 to which the tracking voltage Vtr is applied to determine the voltage value of the output voltage Vout, and a feedback terminal 16 to which a feedback voltage Vfb, indicating the actual voltage value of the output voltage Vout, is provided.

[0009] The circuit 11 can have a known configuration comprising a high-voltage-side transistor 111, which applies the primary supply voltage Vin to the internal output terminal 14 (output node), and a gate driver 112 thereof, a low-voltage-side transistor 113, which connects the internal output terminal 14 to ground, and a gate driver 114 for this, as well as a converter control 115, which feeds a control signal to switch a switching state in a ratio corresponding to the output-side circuit characteristics to the high-voltage-side transistor 111 and the low-voltage-side transistor 113.

[0010] The internal control circuit 12 can, for example, have a configuration with a reference voltage circuit 121 that generates a reference voltage Vref from the primary supply voltage Vin, and a differential amplifier circuit 122 that generates a differential voltage Vdf between a lower of the tracking voltage Vtr or the reference voltage Vref and the feedback voltage Vfb (in a case where the tracking voltage Vtr does not exceed the reference voltage Vref, Vtr - Vfb). It should be noted that the reference voltage Vref is generally used to establish a final control voltage, but can be omitted in a case where control continues with the input voltage of Vtr as the reference voltage.

[0011] The internal output terminal 14 is connected to one end of the output inductor 21, and the output capacitor 22 is connected to the other end. The output inductor 21 and the output capacitor 22 have known configurations that smooth a square wave voltage output by the operation of the high-voltage-side transistor 111 and the low-voltage-side transistor 113. The output inductor 21 and the output capacitor 22 are connected to the circuit 11, thus forming a synchronous DC-DC converter capable of generating the output voltage Vout with a desired voltage value from the primary supply voltage Vin.

[0012] The output feedback circuit 30 generates the feedback voltage Vfb by dividing the output voltage Vout, which indicates the voltage value of the output voltage Vout, and inputs the feedback voltage Vfb to the feedback terminal 16 of the power IC 10.

[0013] The tracking ground circuit 40 is capable of connecting the tracking terminal 15 to ground. That is, the tracking ground circuit 40 diverts the current input from the setting terminal 63 to ground, thereby immediately reducing the tracking voltage Vtr to the ground level. Accordingly, the differential voltage Vdf output by the differential amplifier circuit 122 decreases, and the circuit 11 operates to draw charge from the output capacitor 22. The operation of the circuit 11 described above is a process in which the voltage is increased from the output voltage Vout to the primary supply voltage Vin, allowing energy to be recovered on the primary supply side. Thus, the power supply unit 1 connects the tracking terminal 15 to ground via the tracking ground circuit 40, immediately reducing the output voltage Vout to the ground level.

[0014] The tracking circuit 40 of the present embodiment is an open-collector output circuit. In particular, the tracking circuit 40 comprises, for example, a field-effect transistor 41. The drain (collector) of the transistor 41 is connected to the tracking terminal 15, the source (emitter) of the transistor 41 is connected to ground, and a drive signal is applied to the gate (base) of the transistor 41 by the tracking control circuit 50. To use a transistor that can be operated with a relatively small current as transistor 41, a limiting resistor 631 can be provided between the setting terminal 63 and the tracking terminal 15, and the tracking circuit 40 can be connected downstream of the limiting resistor 631.

[0015] The tracking control circuit 50 outputs a control signal to control the tracking circuit 40, i.e., it switches the gate voltage of transistor 41 on and off. The tracking control circuit 50 is configured to supply a gate current and close transistor 41 when the primary supply voltage Vin decreases. As a concrete example, the tracking control circuit 50 could be a logic circuit that inverts a voltage monitoring signal for the primary supply voltage Vin.

[0016] As described above, in power supply unit 1, the low-capacitance tracking terminal 15 is connected to ground via the tracking ground circuit 40, resulting in a rapid discharge of the output capacitor 22. Therefore, in power supply unit 1, the output voltage Vout is rapidly reduced when the primary supply voltage Vin is switched off. [Second embodiment]

[0017] Fig. Figure 2 is a circuit diagram of a power supply device 1A according to a second embodiment of the present disclosure. The power supply device 1A comprises a power 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 to which a primary supply voltage Vin is applied, an output terminal 62 to which an output voltage Vout is output, and an adjustment terminal 63 to which a tracking voltage Vtr is applied to set the voltage value of the output voltage Vout.

[0018] The power IC 10A comprises a circuit 11 and an internal control circuit 12A, which controls the circuit 11. Furthermore, 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.

[0019] The internal control circuit 12A can have a configuration with a reference voltage circuit 121 that generates a reference voltage Vref, a soft start circuit 123 that generates a slowly rising soft start voltage Vss when the primary supply voltage Vin is fed into the power IC 10A, and a differential amplifier circuit 122 that generates a differential voltage Vdf between a lower of the tracking voltage Vtr or the soft start voltage Vss (within a range that does not exceed the reference voltage Vref) and the feedback voltage Vfb.

[0020] The soft-start circuit 123 comprises a constant-current circuit 1231 which, upon receiving the primary supply voltage Vin, outputs a constant charging current. It is connected to a soft-start capacitor 171, which is charged via the soft-start terminal 17 with the charging current, and generates the soft-start voltage Vss as the terminal voltage of the soft-start capacitor 171. The constant-current circuit 1231 can be configured to adapt to the current supplied by the reference voltage circuit 121.

[0021] The tracking voltage generation circuit 70 is connected to the tracking terminal 15 and generates the tracking voltage Vtr. In particular, the tracking voltage generation circuit 70 of the present embodiment is configured as a regulator that generates the tracking voltage Vtr from the primary supply voltage Vin, and the tracking voltage Vtr is determined according to its resistance value.

[0022] The tracking ground circuit 40A of the present embodiment is a push-pull output circuit whose output is connected to ground or a predetermined potential. Such a tracking ground circuit 40A can, for example, be configured using an IC with a CMOS as the output interface and can therefore be implemented at a relatively low cost. The tracking ground circuit 40A of the present 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 ground circuit 40A. Thus, the limiting diode 42 is provided to expand the selection of ICs that can be used as the tracking ground circuit 40A.

[0023] The tracking control circuit 50A can include components that form the tracking ground circuit 40A, with the exception of the IC. This allows the power supply unit 1A to be designed relatively cost-effectively. In the power supply unit 1A, which is configured to input the tracking voltage Vtr and the soft-start voltage Vss into the differential amplifier circuit 122, in a case where the output voltage Vout is stopped, for example, when the input of the primary supply voltage Vin is switched off or when a signal such as an error signal is input, the tracking control circuit 50A can connect the tracking terminal 15 to ground via the tracking ground circuit 40A after a predetermined time interval has elapsed since the constant current circuit 1231 stopped outputting.Thus, immediately after the output stop process begins, the output voltage Vout is reduced below the soft-start voltage Vss, thereby reducing the inrush current from output capacitor 22 to circuit 11 of the power IC 10A. The tracking voltage Vtr is reduced to ground level at the point when the soft-start capacitor 171 discharges the current to a certain degree, thus immediately completing the discharge of output capacitor 22.

[0024] The power supply unit 1A of the present embodiment comprises the power IC 10A with the soft-start circuit 123, which reduces the rise rate of the output voltage Vout and prevents excessive inrush current. Furthermore, in the power supply unit 1A, at the time the output voltage Vout drops, the tracking ground circuit 40A reduces the tracking voltage Vtr to the level of ground, thereby immediately reducing the output voltage Vout. [Third embodiment]

[0025] Fig. Figure 3 is a circuit diagram of a power supply device 1B according to a third embodiment of the present disclosure. The power supply device 1B comprises a power IC 10B, an output inductor 21, an output capacitor 22, an output feedback circuit 30, a tracking voltage 70B, a tracking ground circuit 40, and a tracking control circuit 50.

[0026] The power IC 10B can have a configuration comprising a reference voltage circuit 121 that generates a reference voltage Vref, a differential amplifier circuit 122 that generates a differential voltage Vdf between a tracking voltage Vtr and a feedback voltage Vfb, and a constant current circuit 124 that outputs a constant charging current to the tracking terminal 15 when a primary supply voltage Vin is applied to the power IC 10B.

[0027] The tracking voltage generation circuit 70B has a soft-start capacitor 71 connected to the tracking terminal 15 and configured to generate a terminal voltage equal to the tracking voltage Vtr by being charged with the charging current output by the constant current circuit 124.

[0028] In the present embodiment, the tracking ground circuit 40 connects the tracking terminal 15 to ground via an adjusting resistor 43. The adjusting resistor 43 reduces the rate of fall of the tracking voltage Vtr and protects the power IC 10 from discharge current. In the present embodiment, the tracking ground circuit 40 is connected to the tracking terminal 15 via the adjusting resistor 43, but can also connect the source of the transistor 41 to ground via the adjusting resistor 43.

[0029] In the power supply unit 1B of the present embodiment, the tracking voltage Vtr rises and falls due to the charging and discharging of the soft-start capacitor 71. When the soft-start capacitor 71 is discharged, the tracking voltage Vtr decreases relatively slowly due to the current consumption of the differential amplifier circuit 122 in a case where the tracking ground circuit 40 is not in use. Connecting the output end of the soft-start capacitor 71 to ground via the tracking ground circuit 40 immediately causes this reduction. In the power supply unit 1B of the present embodiment, the tracking control circuit 50 can also use a drop in the primary supply voltage Vin, a drop in a voltage other than Vin, an abnormal system condition, or the like as a suitable trigger to connect the tracking terminal 15 to ground via the adjusting resistor 43.In this way, the discharge current can be adjusted.

[0030] With regard to the above-mentioned embodiments and modifications, the following additional remarks are disclosed. (Additional Note 1)

[0031] A power supply device (1, 1A, 1B) comprises a power IC (10, 10A, 10B) which includes a circuit (11) with a pair of switching elements (111, 113) which switch with a ratio corresponding to an output-side circuit characteristic and connect an output node to a primary supply voltage or ground, and an internal control circuit (12, 12A, 12B) which controls the circuit (11) and has an internal input terminal (13) to which the primary supply voltage is applied, an internal output terminal (14) from which a square wave voltage output by the switching elements is output, a tracking terminal (15) to which a tracking voltage is applied to fix a voltage value of the output voltage, and a feedback terminal (16) to which a feedback voltage is applied that indicates an actual voltage value of the output voltage;an output inductor (21), one end of which is connected to the internal output terminal (14); an output capacitor (22) connected to the other end of the inductor (21); a tracking ground circuit (40, 40A) that can connect the tracking terminal (15) to ground; and a tracking control circuit (50, 50A) that controls the tracking ground circuit (40, 40A). (Additional Note 2)

[0032] In the power supply device (1A) of Additional Note 1, the internal control circuit (12A) may include a soft-start circuit (123) which may have a constant current circuit (1231) which outputs a constant charging current, is connected to a soft-start capacitor (171) which is charged with the charging current and generates a soft-start voltage which is a terminal voltage of the soft-start capacitor (171), and may have a differential amplifier circuit (122) which generates a differential voltage between a lower of the tracking voltage or the soft-start voltage and the feedback voltage. (Additional Note 3)

[0033] The power supply device (1B) of Additional Note 1 may further include a tracking voltage generating circuit (70B) connected to the tracking terminal (15) and configured to generate the tracking voltage, the internal control circuit (12B) may include a constant current circuit (124) which outputs a constant charging current when the primary supply voltage is applied, and the tracking voltage generating circuit (70B) may include a soft-start capacitor (71) which generates a terminal voltage which serves as the tracking voltage by being charged with the charging current. (Additional note 4)

[0034] In the power supply device (1A, 1B) of additional note 2 or 3, when the output voltage is stopped, the tracking control circuit (50, 50A) can connect the tracking terminal (15) to ground via the tracking ground circuit (40, 40A) after a predetermined time period has elapsed following the stopping of the output of the constant current circuit (1231, 124). (Additional note 5)

[0035] In the power supply device (1, 1B) of one of the additional notes 1 to 4, the tracking circuit (40) can be an open-collector output circuit. (Additional Note 6)

[0036] In the power supply device (1B) of additional note 5, the tracking grounding circuit can connect the tracking terminal (15) to the ground via a resistor. (Additional note 7)

[0037] In the power supply unit (1A) of one of the additional notes 1 to 4, the tracking circuit (40A) can be a push-pull output circuit. (Additional Note 8)

[0038] In the power supply unit (1A) of the additional note 7, the tracking circuit (40A) can be connected to the tracking terminal (15) via a diode (42). (Additional Note 9)

[0039] In the power supply unit of additional note 7, the tracking circuit can be connected to the tracking terminal via a resistor.

[0040] The present disclosure has been described in detail above, but is not limited to the embodiments mentioned above. Various additions, substitutions, modifications, partial omissions, and the like may be made to these embodiments without deviating from the essential nature of the present disclosure or from the spirit of the present disclosure as derived from the content of the claims and their equivalents. These embodiments may be implemented in combination.

[0041] For example, in the power supply of any embodiment, either the open-collector output circuit or the push-pull output circuit can be used as the tracking ground circuit. Thus, a tracking ground circuit comprising a push-pull output circuit can be connected, via a tuning resistor, to a tracking terminal to which a tracking voltage adjustment circuit with a soft-start capacitor is connected. If the voltage range of the internal control circuit and the voltage range of the output voltage are the same, the undivided primary supply voltage and the output voltage can be used as the reference and feedback voltages, respectively.

[0042] In the power supply device according to the present disclosure, not only a single transistor but also a circuit with an open-collector output, such as a comparator, an optocoupler, an integrated circuit or the like with a transistor, can be used as the open-collector output circuit forming the tracking circuit. EXPLANATION OF THE REFERENCE SYMBOLS 1, 1A, 1B Power supply unit 10, 10A, 10B Power IC 11 Circuit 111 high-voltage side transistor 112, 114 Gate Drivers 113 low-voltage side transistor 115 Converter control 12, 12A Internal Control Circuit 121 Reference voltage circuit 122 Differential amplifier circuit 123 Soft start circuit 1231, 124 Constant current circuit 13 Internal input port 14 Internal output port 15 Tracking port 16 Return port 17 Soft start connection 171, 71 Softstart capacitor 21 Output inductance 22 Output capacitor 30 Output feedback loop 40, 40A tracking circle 41 transistors 42 Limiting diode 43 Adjustment resistor 50, 50A Tracking control circuit 61 Input connection 62 Output port 63 Adjustment port 631 Limiting resistor 70, 70B Tracking voltage generation circuit QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2020-78203

[0003]

Claims

[1] A power supply device comprising: a power IC comprising a circuit with a pair of switching elements that switch with a ratio corresponding to an output-side circuit characteristic and connect an output node to a primary supply voltage or ground, and an internal control circuit that controls the circuit and has an internal input terminal to which the primary supply voltage is applied, an internal output terminal from which a square wave voltage output by the switching elements is output, a tracking terminal to which a tracking voltage is applied to adjust a voltage value of an output voltage, and a feedback terminal to which a feedback voltage is applied that indicates an actual voltage value of the output voltage; an output inductance connected to the internal output terminal; an output capacitor connected to the output inductance; a tracking grounding circuit that can connect the tracking terminal to the ground; and a tracking control circuit that controls the tracking circuit. [2] The power supply device according to claim 1, wherein the internal control circuit a soft-start circuit including a constant current circuit that outputs a constant charging current, is connected to a soft-start capacitor that is charged with the charging current, and generates a soft-start voltage that is a terminal voltage of the soft-start capacitor, and a differential amplifier circuit that generates a differential voltage between a lower of the tracking voltage or soft-start voltage and the feedback voltage. [3] The power supply device according to claim 1, further comprising: a tracking voltage generation circuit connected to the tracking terminal and configured to generate the tracking voltage, wherein the internal control circuit has a constant current circuit that outputs a constant charging current, and The tracking voltage generation circuit has a soft-start capacitor that generates a connection voltage, which is intended to be the tracking voltage, by being charged with the charging current. [4] The power supply device according to claim 2 or 3, wherein, when an output of the output voltage is stopped, the tracking control circuit connects the tracking terminal to ground via the tracking ground circuit after a predetermined time interval has elapsed since an output of the constant current circuit was stopped. [5] The power supply device according to any one of claims 1 to 4, wherein the tracking circuit is an open-collector output circuit. [6] The power supply device according to claim 5, wherein the tracking grounding circuit connects the tracking terminal to the ground via a resistor. [7] The power supply device according to any one of claims 1 to 4, wherein the tracking circuit is a push-pull output circuit. [8] The power supply device according to claim 7, wherein the tracking circuit is connected to the tracking terminal via a diode. [9] The power supply device according to claim 7 or 8, wherein the tracking circuit is connected to the tracking terminal via a resistor.

Images