Voltage conversion circuit and voltage conversion device

Abstract

The utility model provides a voltage conversion circuit and a voltage conversion device. The voltage conversion circuit comprises a switching power supply chip, a feedback voltage regulation module, a plurality of current expansion modules connected in parallel, and an output module. The feedback voltage regulating module comprises a reference resistor and a feedback resistor, the reference resistor is connected between the reference voltage end and the feedback end, and the feedback resistor is connected between the feedback end and the first end of the output module; the switching power supply chip is used for outputting a pulse width modulation signal to the modulation signal end, and the duty ratio of the pulse width modulation signal is related to the voltage of the feedback end; the current expanding module comprises a first switch element and a first energy storage element; the first switch element is used for disconnecting the input end of the voltage conversion circuit from the first energy storage element when the pulse width modulation signal is in an invalid level; and the output module is used for discharging to the first energy storage element when the first switch element is switched off, so that the output end outputs negative voltage. The voltage conversion circuit provided by the utility model can improve the output current and meet the requirements of a plurality of vacuum gauges.

Description

Technical Field

[0001] The utility model relates to the field of semiconductor manufacturing, in particular to a voltage conversion circuit and a voltage conversion device. Background Art

[0002] In semiconductor equipment, a vacuum gauge is needed to test the pressure in a chamber or pipeline. The voltage required for a single vacuum gauge is ±15V, and the maximum current required is 600mA. Since two vacuum gauges with different ranges are required in semiconductor equipment, the power supply current of the power supply system should be greater than the sum of the currents required by the two vacuum gauges, that is, the power supply current should be greater than 1.2A.

[0003] For the -15V case, if a linear power supply is used, it is necessary to generate a negative power supply through steps such as AC to DC conversion and filtering, and the power supply needs to be stabilized and filtered. This method produces low conversion efficiency, and the generated negative power supply has accuracy deviation and slightly large ripple. In addition, the heat dissipation and filtering circuit volume need to be considered, which is not suitable for the requirements of modern products for miniaturization of circuits.

[0004] If a switching power supply chip is used to build a circuit that generates a negative power supply, the overall circuit layout can be compact and the output voltage accuracy can be high. However, the current negative power supply circuit cannot achieve an output current of 1.2A when the output voltage meets -15V. Utility Model Content

[0005] The utility model aims to solve at least one of the technical problems existing in the prior art, and proposes a voltage conversion circuit and a voltage conversion device. By setting a plurality of parallel current expansion modules in the voltage conversion circuit, the output current is increased, thereby meeting the current requirements of a plurality of vacuum gauges used in semiconductor process equipment.

[0006] In a first aspect, an embodiment of the utility model provides a voltage conversion circuit, comprising: a switching power supply chip, a feedback voltage regulation module, a plurality of current expansion modules connected in parallel, and an output module; wherein,

[0007] The feedback voltage regulation module includes a reference resistor and a feedback resistor, the reference resistor is connected between the reference voltage terminal and the feedback terminal of the switching power supply chip, and the feedback resistor is connected between the feedback terminal and the first terminal of the output module;

[0008] The switching power supply chip is used to output a pulse width modulation signal to the modulation signal terminal of the switching power supply chip; wherein the duty cycle of the pulse width modulation signal is related to the voltage of the feedback terminal;

[0009] Each of the current expansion modules includes a first switch element and a first energy storage element; the first switch element is used to connect the input end of the voltage conversion circuit with the first energy storage element when the pulse width modulation signal is at an effective level; and disconnect the input end of the voltage conversion circuit from the first energy storage element when the pulse width modulation signal is at an invalid level;

[0010] The second end of the output module is connected to the output end of the voltage conversion circuit, and the third end of the output module is connected to one end of the first energy storage element connected to the first switching element. The output module is used to discharge to the first energy storage element when the first switching element is disconnected, so that the output end outputs a negative voltage.

[0011] In some embodiments, the output module includes a second switch element and a second energy storage element.

[0012] A first end of the second energy storage element is grounded, and a second end of the second energy storage element is connected to an output end of the voltage conversion circuit and one end of the second switch element;

[0013] The other end of the second switch element is connected to one end of the first energy storage element connected to the first switch element, and the second switch element is used to connect the second energy storage element to the first energy storage element when the first switch element is disconnected.

[0014] In some embodiments, the output module further includes: a filter element connected between the second end of the second energy storage element and the output end of the voltage conversion circuit.

[0015] In some embodiments, the second switch element includes a plurality of diodes connected in parallel, and / or the second energy storage element includes a plurality of first capacitors connected in parallel.

[0016] In some embodiments, the current expansion module also includes: a first resistor, the first resistor is connected between the modulation signal end and the control end of the first switching element, the input end of the first switching element is connected to the input end of the voltage conversion circuit, and the output end of the first switching element is connected to the first energy storage element.

[0017] In some embodiments, the switching power supply chip is further used to switch the pulse width modulation signal to a valid level state when the voltage received at the feedback terminal exceeds a preset value.

[0018] In some embodiments, the voltage conversion circuit further includes a timing capacitor, which is connected to the working end of the switching power supply chip; wherein the frequency of the pulse width modulation signal is related to the capacitance of the timing capacitor.

[0019] In some embodiments, the voltage conversion circuit further includes a current limiting resistor, one end of the current limiting resistor is connected to the other end of each of the first energy storage elements and the current limiting end of the switching power supply chip, and the other end of the current limiting resistor is grounded;

[0020] Wherein, the switching power supply chip is also used to stop outputting the pulse width modulation signal when the voltage at the current limiting end exceeds a predetermined value.

[0021] In the second aspect, an embodiment of the utility model also provides a voltage conversion device, including a driving circuit board and the above-mentioned voltage conversion circuit, wherein the voltage conversion circuit is arranged on the driving circuit board; the feedback voltage regulation module and the switching power supply chip are both located on the side of the switching element away from the energy storage element.

[0022] In some embodiments, the driving circuit board includes at least one conductive layer, the voltage conversion circuit also includes a signal transmission line located in the conductive layer, and a heat sink is also provided in the conductive layer.

[0023] The utility model has the following beneficial effects:

[0024] In an embodiment of the utility model, the switching power supply chip of the voltage conversion circuit generates a pulse width modulation signal. When the pulse width modulation signal is in a valid state, the first energy storage element in the current expansion module starts to store energy; when the pulse width modulation signal is in an invalid state, the output module discharges to the first energy storage element, so that the output end of the voltage conversion circuit outputs a negative voltage, thereby realizing the voltage conversion function; in addition, the embodiment of the utility model increases the output current of the voltage conversion circuit by arranging multiple current expansion modules in parallel in the voltage conversion circuit, thereby meeting the power supply requirements of multiple vacuum gauges. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the accompanying drawings:

[0026] Figure 1 The present invention is a schematic diagram of a module of a voltage conversion circuit provided in an embodiment of the present invention.

[0027] Figure 2 The present invention is a schematic diagram of a specific structure of a voltage conversion circuit provided in an embodiment of the present invention.

[0028] Figure 3 It is a schematic diagram of a switching power supply chip provided in an embodiment of the utility model.

[0029] Figure 4It is a schematic diagram of a voltage conversion device provided in some embodiments of the present disclosure. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the voltage conversion circuit and the voltage conversion device provided by the embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0031] Figure 1 Schematic diagram of a module of a voltage conversion circuit provided in an embodiment of the utility model. Figure 2 Schematic diagram of a specific structure of a voltage conversion circuit provided in an embodiment of the utility model, such as Figure 1 As shown, the voltage conversion circuit includes: a switching power supply chip 10, a feedback voltage regulation module 40, a parallel multi-channel current expansion module 20 and an output module 30.

[0032] The switching power supply chip 10 includes: a power supply terminal VCC, a reference voltage terminal VREF, a feedback terminal EAINV and a modulation signal terminal OUT. The feedback voltage regulation module 40 includes a reference resistor Rref and a feedback resistor Rsense, wherein the reference resistor Rref is connected between the reference voltage terminal VREF and the feedback terminal EAINV of the switching power supply chip 10, and the feedback resistor Rsense is connected between the feedback terminal EAINV and the first terminal a of the output module 30.

[0033] The switching power supply chip 10 is used to output a pulse width modulation signal to the modulation signal terminal OUT of the switching power supply chip 10 , wherein the duty cycle of the pulse width modulation signal is related to the voltage of the feedback terminal EAINV.

[0034] In one example, the switching power supply chip 10 is also used to switch the pulse width modulation signal to a valid level state when the voltage received at the feedback terminal EAINV exceeds a preset value (at this time, the absolute value of the voltage output by the output terminal VOUT of the voltage conversion circuit is greater than 15V), thereby achieving the effect of adjusting the duty cycle of the pulse width modulation signal according to the feedback terminal EAINV.

[0035] The current expansion module 20 includes a first switching element Q0 and a first energy storage element L0. The first switching element Q0 is connected to the input terminal VIN1 of the voltage conversion circuit, the first energy storage element L0 and the modulation signal terminal OUT of the switching power supply chip 10. The first switching element Q0 is used to connect the input terminal VIN1 of the voltage conversion circuit and the first energy storage element L0 when the pulse width modulation signal is at a valid level, so that the first energy storage element L0 starts to store energy; and when the pulse width modulation signal is at an invalid level, the first switching element Q0 disconnects the input terminal VIN1 of the voltage conversion circuit from the first energy storage element L0.

[0036] The pulse width modulation signal is a signal that jumps between high and low levels. The effective level refers to the level that can control the first switch element Q0 to be turned on; the invalid level refers to the level that can control the first switch element Q0 to be turned off. For example, if the first switch element Q0 is a PMOS tube, the effective level is a low level and the invalid level is a high level; for another example, if the first switch element Q0 is an NMOS tube, the effective level is a high level and the invalid level is a low level.

[0037] The voltage of the input terminal VIN1 of the voltage conversion circuit may be the same as the above-mentioned power supply voltage, for example, both are +24V.

[0038] The second end b of the output module 30 is connected to the output end VOUT of the voltage conversion circuit, and the third end c of the output module 30 is connected to one end of the first energy storage element L0 connected to the first switch element Q0 (i.e., the upper end of the energy storage element L0). The output module 30 is used to discharge to the first energy storage element L0 when the first switch element Q0 is disconnected, so that the output end VOUT of the voltage conversion circuit outputs a negative voltage. The output end VOUT of the voltage conversion circuit is used to power an external load.

[0039] In the embodiment of the utility model, the switching power supply chip 10 can output a pulse width modulation signal. Taking the first switch element Q0 as a PMOS tube as an example, when the pulse width modulation signal is at a low level, the first switch element Q0 is turned on, so that the input terminal VIN1 of the voltage conversion circuit is turned on with the first energy storage element L0, and the first energy storage element L0 starts to store energy and generates a voltage with positive top and negative bottom; since the current flowing through the first energy storage element L0 cannot change suddenly, the current flowing through the first energy storage element L0 gradually increases from 0 to a steady state. When the pulse width modulation signal is at a high level, the first switch element Q0 is disconnected, so that the input terminal VIN1 of the voltage conversion circuit is disconnected from the first energy storage element L0; and since the current flowing through the first energy storage element L0 cannot change suddenly, the voltage of the first energy storage element L0 becomes positive at the bottom and negative at the top. At this time, the output module 30 discharges to the first energy storage element L0 to offset the negative top and positive bottom voltage of the first energy storage element L0, so that the voltage of the output terminal VOUT is lower than the ground terminal PGND, and a negative voltage is output. The absolute value of the output voltage is determined by the resistance ratio of the feedback resistor Rsense to the reference resistor Rref and the voltage between the reference voltage terminal VREF and the feedback terminal EAINV.

[0040] Specifically, when the current flowing through the feedback resistor Rsense is equal to the current flowing through the reference resistor Rref, the voltage at the feedback terminal EAINV is equal to or approximately equal to 0V. In this case, the output voltage at the output terminal VOUT can be set to the target value by designing the resistance values ​​of the two resistors. Taking the target value equal to -15V as an example, the current flowing through the feedback resistor Rsense is equal to the current flowing through the reference resistor Rref, that is, r sense / r ref =U sense / U ref , where r sense is the resistance of the feedback resistor Rsense, r ref is the resistance of the reference resistor Rref, U sense is the voltage across the feedback resistor Rsense, U ref The switching power chip 10 can output a reference voltage to the reference voltage terminal VREF of the switching power chip 10 according to the power supply voltage received by its power supply terminal VCC. The reference voltage is less than the power supply voltage. For example, if the power supply voltage is +24V and the voltage provided to the reference voltage terminal VREF is 3V, then the voltage U across the reference resistor Rref is ref is 3V, then:

[0041] U sense =U ref *(r sense / r ref )=3*(r sense / r ref )

[0042] The output voltage Vout of the output terminal VOUT of the voltage conversion circuit is Vout=U sense =3*(r sense / r ref ), therefore, the voltage output by the voltage conversion circuit can be determined according to the voltage between the reference voltage terminal VREF and the feedback terminal EAINV and the resistance ratio of the feedback resistor Rsense to the reference resistor Rref. sense / r ref =5, Vout is equal to the above target value (-15V). When the output module 30 discharges to the first energy storage element L0 until the absolute value of Vout exceeds 15V, the current flowing through the feedback resistor Rsense will increase, and the current of the feedback terminal EAINV will increase, and the feedback terminal EAINV exceeds the preset value (the preset value is the voltage of the feedback terminal EAINV when the output terminal VOUT is the target value), and the duty cycle of the pulse width modulation signal changes, thereby changing the disconnection time of the first switch element Q0, so that when the absolute value of the voltage at the output terminal VOUT is greater than the absolute value of the above target value, the first switch element Q0 can be controlled to end the closed state in advance, so that the first energy storage element L0 can store energy again.

[0043] Among them, the current on the first energy storage element L0 in each current expansion module 20 is related to the output current of the switching power supply chip 10. Compared with a single current expansion module 20, when multiple current expansion modules 20 are connected in parallel in the voltage conversion circuit, when the first switching element Q0 is disconnected, the output current of the output terminal VOUT is close to the sum of the currents flowing through the multiple first energy storage elements L0, thereby increasing the output current of the voltage conversion circuit and meeting the use requirements of multiple vacuum gauges.

[0044] In some embodiments, the switching power supply chip 10 further has a working terminal RAMP, such as Figure 2 As shown, the voltage conversion circuit also includes a timing capacitor Cramp, which is connected between the ground terminal PGND and the working terminal RAMP of the switching power supply chip 10. The switching power supply chip 10 is specifically used to output a pulse width modulation signal to the modulation signal terminal OUT according to the voltage received by its feedback terminal EAINV and the capacitance of the timing capacitor Cramp. The frequency of the pulse width modulation signal is related to the capacitance of the timing capacitor Cramp.

[0045] The frequency of the pulse width modulation signal f=1 / (15K*Cra), where Cra is the capacitance of the timing capacitor Cramp.

[0046] The operating frequency of the timing capacitor Cramp may be between 10KHz and 200KHz.

[0047] In one example, the timing capacitor Cramp can be selected with a precision of ±5% or ±1%, and the capacitance of the timing capacitor Cramp is 680pF, so that a pulse width modulation signal with a frequency of about 98KHz can be generated. When the frequency of the pulse width modulation signal is too high, the switching state of the first switch element Q0 will be switched too quickly and excessive heat will be generated; when the frequency of the pulse width modulation signal is too low, the conduction time of the first switch element Q0 will be too long and the output efficiency of the voltage conversion circuit will be low. In the embodiment of the utility model, the switching power supply chip 10 outputs a pulse width modulation signal with a frequency of 98KHz, which can improve the output efficiency of the voltage conversion circuit while reducing heat loss.

[0048] In one example, the output current of the switching power supply chip 10 is between 0 and 0.7 A, and the number of the current expansion modules 20 is two. In this case, the maximum output current of the voltage conversion circuit can reach 1.2V.

[0049] In some examples, the first energy storage element L0 is an inductor, the first switching element Q0 is a MOS tube, the control end of the first switching element Q0 is connected to the modulation signal end OUT of the switching power supply chip 10, the input end of the first switching element Q0 is connected to the input end VIN1 of the switching conversion circuit, and the output end of the first switching element Q0 is connected to the inductor.

[0050] It should be noted that the control end of the first switch element Q0 is the gate of the MOS tube, one of the input end and the output end of the first switch element Q0 is the source, and the other is the drain.

[0051] In one example, the first switch element Q0 is a PMOS tube, and the voltage between the drain and the source in the cut-off state is greater than twice the voltage of the input terminal VIN1 of the voltage conversion circuit to prevent the internal reverse junction capacitance of the PMOS from breaking down.

[0052] It should also be noted that the connection between the control terminal of the first switch element Q0 and the modulation signal terminal OUT may be a direct connection or an indirect connection. Figure 2 As shown, the current expansion module 20 also includes: a first resistor R1. The control end of the first switch element Q0 is indirectly connected to the modulation signal end OUT through the first resistor R1. The first resistor R1 is a protection resistor of the MOS tube, which is used to prevent the MOS tube from oscillating, reduce the charging peak current of the MOS tube gate, and prevent the source and drain of the MOS tube from being broken down.

[0053] In some embodiments, Figure 2 As shown, the output module 30 includes a second switch element 31 and a second energy storage element 32, the first end of the second energy storage element 32 is grounded (i.e., connected to the ground terminal PGND), and the second end of the second energy storage element 32 is connected to the output terminal VOUT of the voltage conversion circuit and one end of the second switch element 31. Among them, the second end 32 of the second energy storage element 32 can be directly or indirectly connected to the output terminal VOUT of the voltage conversion circuit. The other end of the second switch element 31 is connected to the end of the first energy storage element L0 connected to the first switch element Q0 (it should be particularly noted here that the other end of the second switch element 31 is also connected to the feedback resistor 40), and the second switch element 31 is used to connect the second energy storage element 32 to the first energy storage element L0 when the first switch element Q0 is disconnected, so that the second energy storage element 32 discharges to the first energy storage element L0.

[0054] In some embodiments, the second switch element 31 includes a diode D1, the anode of the diode D1 is connected to the first terminal a of the output module 30, and the cathode of the diode D1 is connected to the third terminal c of the output module 30. When the first switch element Q0 is disconnected and the voltage of the first energy storage element L0 is positive at the bottom and negative at the top, the voltage of the third terminal c of the output module 30 is less than the voltage of the first terminal a of the output module 30, therefore, the diode D1 is turned on, and the second energy storage element 32 discharges to the first energy storage element L0.

[0055] In one example, the diode D1 is a Schottky diode, whose withstand voltage is greater than 60V and maximum continuous current is greater than 3A.

[0056] In one example, the second switch element 31 may include one diode D1, or may include multiple diodes D1. When the second switch element 31 includes multiple diodes D1, the multiple diodes D1 are connected in parallel. The second energy storage element 32 may include one or more first capacitors C1. When the second energy storage element 32 includes multiple first capacitors C1, the multiple first capacitors C1 are connected in parallel.

[0057] In some embodiments, Figure 2 As shown, the output module 30 further includes: a filter element 33, which is connected between the second end of the second energy storage element 32 and the output end of the voltage conversion circuit, that is, the second end of the second energy storage element 32 is indirectly connected to the second end b of the output circuit 30 through the filter element 33. The filter element 33 is used to filter out interference signals in the output current.

[0058] The filter element 33 includes a first inductor L1 , and the first inductor L1 is connected between the second end of the second energy storage element 32 and the second end b of the output circuit 30 .

[0059] In some embodiments, Figure 2 As shown, the voltage conversion circuit also includes a second capacitor C2, one end of the second capacitor C2 is connected to the power supply terminal VIN2 and the power supply terminal VCC of the switching power supply chip 10, and the other end of the second capacitor C2 is connected to the ground terminal PGND. The second capacitor C2 is used as a filter capacitor to filter the voltage provided by the power supply terminal VIN2 to ensure the voltage stability of the power supply terminal VIN2.

[0060] In some embodiments, Figure 2 As shown, the voltage conversion circuit further includes a third capacitor C3, one end of the third capacitor C3 is connected to the input terminal VIN1 of the voltage conversion circuit and the input terminal of the first switch element Q0, and the other end of the third capacitor C3 is connected to the ground terminal PGND. The third capacitor C3 is used as a filter capacitor to filter the voltage of the input terminal VIN1 to ensure the voltage stability of the input terminal VIN1.

[0061] In some embodiments, Figure 2As shown, the voltage conversion circuit also includes a current limiting resistor R3, one end of the current limiting resistor R3 is connected to the other end of each first energy storage element L0 (i.e., the end of the first energy storage element L0 away from the first switch element Q0) and the current limiting end CS of the switching power supply chip 10, and the other end of the current limiting resistor R3 is connected to the ground end RGND. When the current flowing through the first energy storage element L0 increases, the current flowing through the current limiting resistor R3 increases accordingly, and the voltage across the current limiting resistor R3 (i.e., the voltage received by the current limiting end CS) also increases accordingly; wherein the switching power supply chip 10 is also used to stop outputting the pulse width modulation signal when the voltage of the current limiting end CS exceeds a predetermined value (for example, the predetermined value is 0.2V) to prevent the output current from being too large.

[0062] In an example, the current limiting resistor R3 is packaged in alloy resistor 2512 and has a maximum power of 1W. Assuming that the maximum output current of the voltage conversion circuit is 1.2A, according to the formula P=I*I*R, it can be concluded that R=P / (I*I)=1W / (1.2A*1.2A)=0.69Ω, that is, the resistance value of the current limiting resistor R3 is not greater than 0.69Ω.

[0063] In some embodiments, Figure 2 As shown, the voltage conversion circuit also includes: an RC oscillator circuit, which includes: a second resistor R2, a fourth capacitor C4 and a fifth capacitor C5, the second resistor R2 is connected in parallel with the fourth capacitor C4, the fifth capacitor C5 is connected between the fourth capacitor C4 and the error output terminal ENOUT of the switching power supply chip 10, and the fourth capacitor C4 is connected between the fifth capacitor C5 and the feedback terminal ENINV of the switching power supply chip 10. The second resistor R2, the fourth capacitor C4 and the fifth capacitor C5 form a double-pole single-zero loop compensation circuit, which can form a non-continuous voltage type control, so that the switching power supply chip 10 adjusts the stability of the pulse width modulation signal output by itself, reduces damped oscillation, and maintains the stability of the output current.

[0064] Figure 3 Schematic diagram of a switching power supply chip provided in an embodiment of the utility model. In some embodiments, the switching power supply chip 10 adopts a flyback switching power supply chip, the input voltage (the voltage of the power supply terminal VCC) is 4.75-30V, and the output current is 0-0.7A. Figure 3As shown, the switching power supply chip 10 has a feedback terminal EAINV, an error output terminal EAOUT, a current limiting terminal CS, a power supply terminal VCC, a ground voltage terminal GND, a reference voltage terminal VREF, a working terminal RAMP and a modulation signal terminal OUT. The switching power supply chip 10 includes: an error amplifier 11, a voltage amplifier 12, a PWM comparator 13, a first OR gate 14, an SR latch 15, a second OR gate 16, a common-phase buffer 17, an oscillator 18, a current limiting comparator 19, and an under voltage lockout (Under Voltage Lock Out, UVLO) device 191.

[0065] Among them, the first input terminal of the error amplifier 11 is grounded, the second input terminal is connected to the feedback terminal EAINV of the switching power supply chip 10, and the output terminal is connected to the error output terminal EAOUT of the switching power supply chip 10. The first input terminal of the voltage amplifier 12 is connected to the reference voltage terminal (whose voltage is, for example, 1.8V), the second input terminal of the voltage amplifier 12 is connected to the output terminal of the error amplifier 11 through the fourth resistor R4, and a fifth resistor R5 is connected between the second input terminal and the output terminal of the voltage amplifier 12. For example, the resistance of the fifth resistor R5 is 1.5 times the resistance of the fourth resistor R4. The first input terminal of the PWM comparator 13 is connected to the working terminal RAMP, and the second input terminal is connected to the output terminal of the voltage amplifier 12. The CT terminal of the oscillator 18 is connected to the working terminal RAMP, so as to generate a clock signal of a certain frequency according to the external timing capacitor Cramp connected to the working terminal RAMP. The first input terminal of the current limiting comparator 19 is connected to the second reference voltage terminal (whose voltage is, for example, 0.2V), and the second input terminal is connected to the current limiting terminal CS. The current limiting comparator 19 is used to compare the voltages of the first input terminal and the second input terminal. The first input terminal of the first OR gate 14 is connected to the output terminal of the PWM comparator 13, and the second input terminal is connected to the output terminal of the current limiting comparator 19. The S terminal of the SR latch 15 is connected to the first OR gate 14, and the R terminal is connected to the clock output terminal CLK of the oscillator 18.

[0066] The input terminal VIN of the undervoltage lockout device 191 is connected to the power supply terminal VCC, and the output terminal VOUT' of the undervoltage lockout device 191 is connected to the reference voltage terminal VREF of the switching power supply chip 10. The undervoltage lockout device 191 can adjust the voltage signal received by the power supply terminal VCC and output a reference voltage; and when the voltage of the power supply terminal VCC is greater than or equal to the undervoltage protection threshold, its undervoltage protection terminal UVLO outputs a low-level signal; and when the voltage of the power supply terminal VCC is less than the undervoltage protection threshold, its undervoltage protection terminal UVLO outputs a high-level signal, thereby ensuring that the switching power supply chip 10 does not work when the input voltage is less than the undervoltage protection threshold, and is in a protection state.

[0067] The first input terminal of the second OR gate 16 is connected to the output terminal of the SR latch, the second input terminal is connected to the output terminal of the oscillator 18, and the third input terminal is connected to the under-voltage lockout terminal UVLO of the under-voltage lockout device 191. The output terminal of the second OR gate 16 is connected to the input terminal of the non-inverting buffer 17, and the output terminal of the non-inverting buffer 17 is connected to the modulation signal terminal OUT of the switching power supply chip 10.

[0068] Figure 4 is a schematic diagram of a voltage conversion device provided in some embodiments of the present disclosure, such as Figure 4 As shown, the voltage conversion device includes a driving circuit board 100 and the above-mentioned voltage conversion circuit arranged on the driving circuit board. Figure 4 The figure only shows the driving circuit board 100 and the positions of the components in the voltage conversion circuit on the driving circuit board 100, but does not reflect the actual components in the circuit. Figure 4 As shown, the feedback voltage regulating module 40 and the switching power chip 10 are both located on the side of the first switching element Q0 away from the first energy storage element L0. Since the first energy storage element L0 generates heat due to energy storage during the operation of the voltage conversion circuit, the feedback voltage regulating module 40 and the switching power chip 10 are arranged on the side of the first switching element Q0 away from the first energy storage element L0, which can reduce the influence of the heating of the first energy storage element L0 on the feedback resistor Rsense, the reference resistor Rref and the switching power chip 10 of the feedback voltage regulating module 40.

[0069] like Figure 4 As shown, the driving circuit board 100 includes a first edge E1 and a second edge E2 opposite to each other, and a third edge E3 and a fourth edge E4 opposite to each other, a plurality of first energy storage elements L0 are arranged near the first edge E1, and a feedback resistor Rsense and a reference resistor Rref are arranged near the second edge E2. A plurality of first switching elements Q0 are arranged adjacent to the plurality of first energy storage elements L0, and a plurality of first resistors R1 are arranged on one side of the plurality of first switching elements Q0 away from the plurality of energy storage elements L0.

[0070] like Figure 4 As shown, the timing capacitor Cramp is arranged on the side of the plurality of first resistors R1 away from the plurality of first switch elements Q0. The first inductor L1 is arranged at a position close to the third edge E3, the first capacitor C1 is arranged at a position close to the first inductor L1, and the diode D1 is arranged between the first inductor L1 and the switch element Q0; the current limiting resistor R3 is arranged at a position close to the first edge E1, the second capacitor C2 is arranged at a side of the switching power supply chip 10 close to the first capacitor C1, and the third capacitor C3 is arranged at a position close to the second edge E2. The second resistor R2, the fourth capacitor C4, and the fifth capacitor C5 are arranged on the side of the third capacitor C3 close to the feedback resistor Rsense.

[0071] In actual design, the trace width in the circuit can be designed according to the maximum output current of the voltage conversion circuit. For example, if the maximum output current of the voltage conversion circuit is 1.2A, the width of the signal transmission line in the voltage conversion circuit should be greater than 30mil.

[0072] In some embodiments, the driving circuit board includes at least one conductive layer, and the signal transmission lines in the voltage conversion circuit are all located in the conductive layer. The signal transmission line refers to a signal line used to connect different ports or different components. For example, a signal transmission line is connected between the power supply terminal VIN2 and the power supply terminal VCC, and between the first switching element Q0 and the first energy storage element L0. The number of conductive layers in the driving circuit board can be one or more layers, such as 2 layers, 4 layers, etc. When the number of conductive layers is multiple layers, there is a dielectric board between two adjacent conductive layers, and a signal transmission line between two components can be located in one conductive layer, or a cross-layer design can be performed, that is, a part of the signal transmission line is located in one of the conductive layers, and the other part of the signal transmission line is located in another conductive layer. The two parts of the signal transmission line are connected by means of metal vias that pass through the dielectric board.

[0073] In order to improve the heat dissipation effect of the circuit, a heat sink can be provided in the conductive layer to increase the heat dissipation area of ​​the circuit. At the same time, when heat sinks are provided in multiple conductive layers, the heat sinks of two adjacent layers can be connected by metal vias to further improve the heat dissipation effect. In addition, the surface of at least a portion of the heat sink is no longer coated with a protective layer to improve the heat dissipation effect.

[0074] In the embodiment of the utility model, the layout of the voltage conversion circuit on the driving circuit board 100 is relatively compact, wherein the size of the driving circuit board 100 can be 50 mm*50 mm, which is suitable for miniaturization of the circuit.

[0075] Table 1 is a voltage, current and temperature test table of the voltage conversion circuit in the embodiment of the utility model. Among them, the ambient temperature during the test was 26°C, and an electronic load was used as a constant current load. Table 1 statistics the temperature rise and conversion efficiency when the voltage conversion circuit outputs 0.6A, 0.8A, 1A, 1.2A and 1.3A for 10 minutes. Among them, the conversion efficiency is the ratio of output power to input power; the higher the conversion efficiency, the less heat is generated and the lower the temperature rise. Through testing, it was found that the maximum power of the voltage conversion circuit in the utility model does not exceed 18.5W, among which, when the output current is 1.2A, the temperature rise does not exceed 40°C, and the conversion efficiency is above 80%, and the output voltage is -15V ±5, which meets the requirements for powering the vacuum gauge, and the temperature rise is low, which has little impact on circuit components.

[0076]

[0077] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

[0078] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0079] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "plurality" means two or more.

[0080] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or an electrical connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0081] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0082] The above description is only a partial implementation mode of the present utility model. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present utility model. These improvements and modifications should also be regarded as the protection scope of the present utility model.

Claims

1. A voltage conversion circuit, characterized in that: include: Switching power supply chip, feedback voltage regulation module, multiple parallel current expansion modules, output module; wherein, The feedback voltage regulation module includes a reference resistor and a feedback resistor, the reference resistor is connected between the reference voltage terminal and the feedback terminal of the switching power supply chip, and the feedback resistor is connected between the feedback terminal and the first terminal of the output module; The switching power supply chip is used to output a pulse width modulation signal to the modulation signal terminal of the switching power supply chip; wherein the duty cycle of the pulse width modulation signal is related to the voltage of the feedback terminal; Each of the current expansion modules includes a first switch element and a first energy storage element; a first end of the first energy storage element is connected to the first switch element, and the first switch element is used to connect the input end of the voltage conversion circuit to the first energy storage element when the pulse width modulation signal is at a valid level; and disconnect the input end of the voltage conversion circuit from the first energy storage element when the pulse width modulation signal is at an invalid level; The second end of the output module is connected to the output end of the voltage conversion circuit, and the third end of the output module is connected to the first end of the first energy storage element. The output module is used to discharge to the first energy storage element when the first switch element is disconnected, so that the output end outputs a negative voltage.

2. The voltage conversion circuit according to claim 1, characterized in that: The output module includes a second switch element and a second energy storage element. A first end of the second energy storage element is grounded, and a second end of the second energy storage element is connected to an output end of the voltage conversion circuit and one end of the second switch element; The other end of the second switch element is connected to the first end of the first energy storage element, and the second switch element is used to connect the second energy storage element and the first energy storage element when the first switch element is disconnected.

3. The voltage conversion circuit according to claim 2, characterized in that: The output module further includes: a filter element connected between the second end of the second energy storage element and the output end of the voltage conversion circuit.

4. The voltage conversion circuit according to claim 2, characterized in that: The second switch element includes a plurality of diodes connected in parallel, and / or the second energy storage element includes a plurality of first capacitors connected in parallel.

5. The voltage conversion circuit according to any one of claims 1 to 4, characterized in that: The current expansion module also includes: a first resistor, the first resistor is connected between the modulation signal end and the control end of the first switch element, the input end of the first switch element is connected to the input end of the voltage conversion circuit, and the output end of the first switch element is connected to the first energy storage element.

6. The voltage conversion circuit according to any one of claims 1 to 4, characterized in that: The switching power supply chip is also used to switch the pulse width modulation signal to a valid level state when the voltage received at the feedback end exceeds a preset value.

7. The voltage conversion circuit according to any one of claims 1 to 4, characterized in that: The voltage conversion circuit also includes a timing capacitor, which is connected to the working end of the switching power supply chip; wherein the frequency of the pulse width modulation signal is related to the capacitance of the timing capacitor.

8. The voltage conversion circuit according to any one of claims 1 to 4, characterized in that: The voltage conversion circuit further includes a current limiting resistor, one end of which is connected to the other end of each of the first energy storage elements and the current limiting end of the switching power supply chip, and the other end of which is grounded; Wherein, the switching power supply chip is also used to stop outputting the pulse width modulation signal when the voltage at the current limiting end exceeds a predetermined value.

9. A voltage conversion device, characterized in that: It comprises a driving circuit board and a voltage conversion circuit as described in any one of claims 1 to 8, wherein the voltage conversion circuit is arranged on the driving circuit board; the feedback voltage regulation module and the switching power supply chip are both located on a side of the switching element away from the energy storage element.

10. The voltage conversion device according to claim 9, characterized in that: The driving circuit board includes at least one conductive layer, the voltage conversion circuit also includes a signal transmission line located in the conductive layer, and a heat sink is also arranged in the conductive layer.

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