Switching power supply circuit for electrical nerve stimulation

Abstract

The invention discloses a switching power supply circuit for electrical nerve stimulation, and the circuit comprises a power switch module which is used for controlling an input voltage to periodically charge and discharge an output capacitor, so as to form a first output voltage; the PWM control module is used for sampling the first output voltage and generating a PWM control signal according to a comparison result of a sampling value and a reference voltage; and the power tube driving module is used for driving a power switch according to the PWM control signal so as to obtain a second output voltage for nerve electrical stimulation. The circuit provided by the invention is an electrical stimulation circuit capable of realizing constant-voltage and constant-current stimulation, and also capable of realizing positive-voltage and negative-voltage stimulation with the same electric charge quantity, so that the problem of charge balance is solved; meanwhile, the problems existing during high-impedance electrode stimulation and the problem that the duty ratio of switching power supply PWM control is too small can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies and neural electrical stimulation, and in particular to a switching power supply circuit for neural electrical stimulation. Background Art

[0002] The switching power supply circuit is a high-efficiency power conversion circuit that can provide stable output voltage and output current. However, the duty cycle of the PWM (pulse width modulation) control signal of the current high-to-low switching power supply circuit is too low, which limits the increase in the switching frequency, thereby causing the dynamic performance of the circuit to decrease.

[0003] Neuroelectrical neurostimulation technology has been widely used in clinical practice, including spinal cord stimulation for pain, deep brain stimulation for Parkinson's disease, vagus nerve stimulation for depression, etc. Current neuroelectrical neurostimulation methods include voltage stimulation and current stimulation. Voltage stimulation has safety issues because the amount of injected charge cannot be controlled; current stimulation wastes a lot of energy in the circuit, and the efficiency of neurostimulation devices is not high, so patients may need to frequently replace equipment.

[0004] The neural electrical stimulation circuit stimulates or inhibits the target neural activity by generating a pulse signal of a certain frequency, thereby regulating the neural activity to achieve a therapeutic effect. However, the unipolar pulse signal stimulation will accumulate electric charge in human tissue, which will have adverse effects on the human body.

[0005] Currently, the diameter of stimulation electrodes in neural electrical stimulation circuits is getting smaller and smaller, which makes the impedance of stimulation electrodes larger and larger. Therefore, an electrical stimulator with a larger output voltage range is needed. The current low output voltage electrical stimulation circuits can hardly meet this demand. Summary of the invention

[0006] The present invention provides a switching power supply circuit for neural electrical stimulation, which can realize the generation of positive and negative voltages, and can also be applied to neuron stimulation. The neural electrical stimulation circuit that can realize constant voltage and constant current stimulation has higher efficiency than the current electrical stimulation circuit, and solves the problem of low efficiency of the electrical stimulation circuit. In addition, positive voltage and negative voltage stimulation can be realized at the same time, and the output voltage and output current can be adjusted according to demand to solve the charge balance problem. The output voltage range of the switching power supply circuit provided by the present invention is larger, and the required charge can be injected at high output impedance, solving the problem encountered during high impedance electrode stimulation. And because the output of the switching power supply circuit has positive voltage and negative voltage, the duty cycle of the PWM control signal is relatively high, thereby solving the problem that the duty cycle of the current switching power supply PWM control is too small.

[0007] According to a first aspect of the present invention, the present invention provides a switching power supply circuit for neural electrical stimulation, the circuit comprising:

[0008] A power switch module, used for controlling the input voltage to periodically charge and discharge the output capacitor to form a first output voltage;

[0009] A PWM control module, used for sampling the first output voltage and generating a PWM control signal according to a comparison result between the sampled value and a reference voltage;

[0010] The power tube driving module is used to drive the power switch according to the PWM control signal to obtain a second output voltage for neural electrical stimulation.

[0011] Furthermore, the power switch module includes a switch tube module and a power output submodule;

[0012] The switch tube module includes a plurality of switch tubes and a flying capacitor, and is used to control the on or off of the plurality of switch tubes;

[0013] The power output submodule includes an inductor, a resistor and an output capacitor, and is used to output a first output voltage.

[0014] Furthermore, the switch tube module includes a first switch tube S1, a second switch tube S2, a third switch tube S3, a fourth switch tube S4, a fifth switch tube S5 and a flying capacitor C F The power output submodule includes an inductor L, an equivalent series resistor ESR, and an output resistor R O And the output capacitor C O ;

[0015] The first terminal of the first switch tube S1 is connected to the input voltage V IN The second end is respectively connected to the first end of the second switch tube S2, the first end of the fifth switch tube S5, and the flying capacitor C F A first end is connected;

[0016] The second end of the second switch tube S2 is connected to the first end of the third switch tube S3 and the first end of the inductor L respectively;

[0017] The second end of the third switch tube S3 is respectively connected to the flying capacitor C F The second end of the switch tube S4 is connected to the first end of the switch tube S4;

[0018] The second end of the inductor L is respectively connected to the first end of the equivalent series resistor ESR, the output resistor R O A first end is connected;

[0019] The second end of the equivalent series resistor ESR is connected to the output capacitor C O The first end of the output capacitor C O The first end outputs a first output voltage VOUT .

[0020] Furthermore, when the first switch tube S1, the second switch tube S2, and the fourth switch tube S4 are in the on state, and the third switch tube S3 and the fifth switch tube S5 are in the off state, the input voltage V IN The output capacitor C O Charging;

[0021] When the first switch tube S1, the second switch tube S2, and the fourth switch tube S4 are in the off state, and the third switch tube S3 and the fifth switch tube S5 are in the on state, the output capacitor C O Discharge.

[0022] Further, the PWM control module includes an error amplifier, a sawtooth wave generating circuit and a PWM wave generating circuit; the PWM wave generating circuit includes a first comparator, an SR latch and a dead time control module;

[0023] The inverting terminal of the error amplifier samples the voltage V FB , the in-phase terminal is connected to the reference voltage, and the output terminal is connected to the in-phase terminal of the first comparator;

[0024] The inverting terminal of the first comparator is connected to the output terminal of the sawtooth wave generating circuit, and the output terminal is connected to the R terminal of the SR latch;

[0025] The S terminal of the SR latch is connected to the output terminal of the sawtooth wave generating circuit, the output terminal is connected to the input terminal of the dead time control module, and the output terminal of the dead time control module is connected to the power tube driving module.

[0026] Furthermore, the first comparator performs a FB comparing with the reference voltage and generating a square wave according to the comparison result;

[0027] The SR latch inputs the square wave into the dead time control module according to the clock signal;

[0028] The dead time control module generates a PWM control signal according to the square wave.

[0029] Further, the error amplifier includes a second resistor R2, a first capacitor C1 and a second capacitor C2;

[0030] The second resistor R2 is connected in series with the second capacitor C2, and then connected in parallel with the first capacitor C1.

[0031] Further, the sawtooth wave generating circuit includes a current source, a third capacitor C3, a switch and a second comparator;

[0032] The current source charges the third capacitor C3 to control the rise of the sawtooth wave;

[0033] The second comparator controls the switch to be turned on, so as to control the third capacitor C3 to discharge, so as to control the decrease of the sawtooth wave.

[0034] Further, the power tube driving module includes a bidirectional level converter and a driving circuit, the bidirectional level converter includes a high level converter and a low level converter, and the driving circuit includes a multi-stage inverter;

[0035] The low level converter is used to convert the square wave signal in the high voltage domain into a square wave signal in the low voltage domain;

[0036] The high level converter is used to convert the square wave signal in the low voltage domain into a square wave signal in the high voltage domain;

[0037] The driving circuit is used to drive the load to ensure that the PWM signal output by the bidirectional level converter can generate a corresponding voltage change at the gate of the switch tube.

[0038] By using one or more of the above-mentioned embodiments of the present invention, at least the following technical effects can be achieved: the switching power supply circuit for neural electrical stimulation provided by the present invention can realize an electrical stimulation circuit with constant voltage and constant current stimulation, uses an inductor to realize constant current stimulation, does not use a current mirror circuit to reduce additional power consumption, and has higher efficiency than the current electrical stimulation circuit; by utilizing the characteristic that the voltage across the capacitor cannot change suddenly, it can realize positive and negative pressure stimulation with the same charge amount, solving the charge balance problem; by using a high-voltage tube, the output voltage range is very large, and the adjustable range of the output voltage is larger than that of the current electrical stimulation circuit, solving the problem existing in high-impedance electrode stimulation; and because the potential of the flying capacitor connected to the output point has positive and negative voltages, the proportion of the time that the power switch is turned on is larger than that of the current switching power supply, solving the problem that the duty cycle of the switching power supply PWM control is too small. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The technical solutions and other beneficial effects of the present invention will be made apparent by describing in detail the specific embodiments of the present invention in conjunction with the accompanying drawings.

[0040] Figure 1 A schematic diagram of the structure of a switching power supply circuit for neural electrical stimulation provided by an embodiment of the present invention;

[0041] Figure 2 A schematic diagram of the structure of a power switch module provided in an embodiment of the present invention;

[0042] Figure 3A schematic diagram of the structure of a PWM control module provided in an embodiment of the present invention;

[0043] Figure 4 A schematic diagram of the structure of a power tube driving module provided by an embodiment of the present invention;

[0044] Figure 5 A comparison diagram of the operating timing of the switching power supply circuit provided in an embodiment of the present invention.

[0045] Explanation of the accompanying drawings: 11-power switch module; 12-PWM control module; 13-power tube driving module; 111-switch tube sub-module; 112-power output sub-module; 121-error amplifier; 122-sawtooth wave generating circuit; 123-PWM wave generating circuit; 124-first comparator; 125-SR latch; 126-dead time control module; 132-bidirectional level converter; 131-driving circuit. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0047] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "and / or" herein is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " herein, unless otherwise specified, generally indicates that the associated objects before and after are in an "or" relationship.

[0048] The switching power supply circuit for neural electrical stimulation provided by the present invention is described in detail below with reference to the accompanying drawings.

[0049] like Figure 1 As shown, a switching power supply circuit 1 for neural electrical stimulation includes a power switch module 11, a PWM control module 12 and a power tube drive module 13. The power switch module 11 is connected to the PWM control module 12, and the PWM control module 12 is connected to the power tube drive module 13.

[0050] The power switch module 11 is used to control the input voltage to periodically charge and discharge the output capacitor to form a stable first output voltage.

[0051] The PWM control module 12 is used to sample the first output voltage, and obtain PWM control signals with different duty cycles according to a comparison result between the sampled value and the reference voltage through negative feedback control.

[0052] The power tube driving module 13 is used to amplify the on and off time of the driving power switch in one cycle according to the PWM control signal to obtain a stable second output voltage for neural electrical stimulation. That is, the power tube driving module 13 shifts the PWM control signal level to a higher voltage domain to drive the power switch to turn on or off to adjust the output voltage and keep the voltage difference between the power tube ports from exceeding its withstand voltage.

[0053] Furthermore, if Figure 2 As shown, the power switch module 11 includes a switch tube module 111 and a power output submodule 112 .

[0054] The switch tube module 111 includes a plurality of switch tubes and a flying capacitor, and is used to control the on or off of the plurality of switch tubes.

[0055] The power output submodule 112 includes an inductor, a resistor, and an output capacitor, and is configured to output a first output voltage.

[0056] Furthermore, the switch tube module 111 includes a first switch tube S1, a second switch tube S2, a third switch tube S3, a fourth switch tube S4, a fifth switch tube S5 and a flying capacitor C F The power output submodule 112 includes an inductor L, an equivalent series resistor ESR, an output resistor R O And the output capacitor C O .

[0057] The first terminal of the first switch tube S1 is connected to the input voltage V IN The second end is respectively connected to the first end of the second switch tube S2, the first end of the fifth switch tube S5, and the flying capacitor C F The first end of the connection.

[0058] The second end of the second switch tube S2 is connected to the first end of the third switch tube S3 and the first end of the inductor L respectively.

[0059] The second end of the third switch tube S3 is respectively connected to the flying capacitor C F and the first end of the fourth switch tube S4 are connected.

[0060] The second end of the inductor L is respectively connected to the first end of the equivalent series resistor ESR, the output resistor R O The first end of the connection.

[0061] The second end of the equivalent series resistor ESR is connected to the output capacitor C O The first end of the output capacitor C O The first end outputs a first output voltage V OUT .

[0062] The first end of the inductor L outputs a periodic positive or negative voltage V LX , to provide effective neural electrical stimulation. Output capacitor C O The first output voltage V OUT It is a stable voltage value, which is used to provide stable voltage and current to the load.

[0063] When the first switch tube S1, the second switch tube S2, and the fourth switch tube S4 are in the on state, and the third switch tube S3 and the fifth switch tube S5 are in the off state, the input voltage V IN The output capacitor C O Charging is performed. At this time, the entire switch tube module 111 is in the on state, and the voltage at the left end of the inductor L is V IN , the voltage difference across the inductor L is V IN -V OUT .

[0064] When the first switch tube S1, the second switch tube S2, and the fourth switch tube S4 are in the off state, and the third switch tube S3 and the fifth switch tube S5 are in the on state, the output capacitor C O Discharge is performed. At this time, the entire switch tube module 111 is in the off state. The first end of the flying capacitor is connected to the ground, and the second end is connected to the first end of the inductor L. Since the voltage difference between the two ends of the flying capacitor cannot change suddenly, the voltage at the first end of the inductor is -V IN , the voltage difference across the inductor is V IN +V OUT .

[0065] As can be seen from the above, the voltage difference across the inductor L in the on state of the switch tube module 111 and the voltage difference across the inductor L in the off state do not change much. Therefore, the on state time and the off state time of the switch tube module 111 are also not much different, and the duty cycle is maintained at 50%, and the on time T ON The specific calculation is: T ON =0.5T(1+V OUT / V IN ), where T is the switching period, and V OUT Less than V IN , so the duty cycle corresponding to the on-time of the switching cycle changes very little, which can increase the switching frequency and solve the problems existing in the current switching power supply. Figure 5As shown, the switch duty cycle corresponding to the circuit provided in the embodiment of the present invention is a larger square wave compared to the switch duty cycle in the prior art. When the large square wave is high, the switch tube module 111 is in the on state, and when the square wave is low, the switch tube module 111 is in the off state. It can be seen that the duty cycle corresponding to the circuit provided by the present invention has been greatly improved.

[0066] In addition, in one cycle, the switch tube module 111 includes an on state and an off state, and the alternating cycle of the on state and the off state makes the output capacitor C O Continuously charging and discharging can keep the output voltage and corresponding current stable, thus achieving constant output voltage and current. F The voltage difference between the two ends cannot change suddenly. When the switch tube module 111 is in the on state, the flying capacitor C F The first end of the inductor L is connected to the input voltage to charge the output capacitor C O charging, outputting the first output voltage, and outputting a positive voltage; when the switch tube module 111 is in the off state, the flying capacitor C F The first terminal is connected to the ground, and the second terminal is connected to the second output voltage V LX , so that the second output voltage V LX It is negative, thus outputting negative pressure, and achieving charge balance through periodic positive and negative pressure stimulation.

[0067] The voltage V in the power output stage OUT When the sampling voltage V FB Will also decrease.

[0068] It should be noted that the first switch tube S1, the second switch tube S2, the third switch tube S3, the fourth switch tube S4, and the fifth switch tube S5 are all high-voltage power tubes, so the input voltage and output voltage of each switch tube can be very high. LX It can output very high output voltage and achieve excellent nerve electrical stimulation effect in high impedance electrode applications.

[0069] The switching power supply circuit for neural electrical stimulation provided by the embodiment of the present invention can accurately control the output voltage V IN The size of the inductor is used to achieve the best neural electrical stimulation circuit. Since the voltage difference across the flying capacitor cannot change suddenly, the capacitor has no discharge path when switching. The voltage at the left end of the inductor in the on state within one cycle is: V LX =V IN , the voltage at the left end of the inductor in the off state is V LX =-V IN , so the voltage at the left end of the inductor is V LXAs a nerve electrical stimulation voltage, it can provide positive and negative voltage stimulation of the same magnitude to achieve charge balance. LX The voltage is connected to the inductor, and the current of the inductor cannot change suddenly. The negative feedback regulation of the control circuit can maintain the current stability and achieve constant current neural electrical stimulation, thus providing effective stimulation effect.

[0070] In some embodiments of the present invention, Figure 3 As shown, the PWM control module 12 includes an error amplifier 121, a sawtooth wave generating circuit 121 and a PWM wave generating circuit 123. The outputs of the error amplifier 121 and the sawtooth wave generating circuit 121 are both inputs of the PWM wave generating circuit 123, and the PWM wave generating circuit 123 compares the two inputs to generate a square wave with a certain duty cycle to control the on and off of the power tube.

[0071] Specifically, the PWM wave generating circuit 123 includes a first comparator 124 , an SR latch 125 and a dead time control module 126 .

[0072] The inverting terminal of the error amplifier 121 is connected to the sampling voltage V FB , the in-phase terminal is connected to the reference voltage, and the output terminal is connected to the in-phase terminal of the first comparator 124. Among them, the sampling voltage V FB When it falls, the output of the error amplifier 121 becomes larger.

[0073] The inverting terminal of the first comparator 124 is connected to the output terminal of the sawtooth wave generating circuit 121, and the output terminal is connected to the R terminal of the SR latch 125. When the output of the error amplifier 121 increases, the voltage at the non-inverting terminal of the first comparator 124 increases, so that the high level of the output PWM wave accounts for a larger proportion, that is, the duty cycle of the PWM is larger.

[0074] The S terminal of the SR latch 125 is connected to the output terminal of the sawtooth wave generating circuit 121, and the output terminal is connected to the input terminal of the dead time control module 126, and the output terminal of the dead time control module 126 is connected to the power tube driving module 13. The dead time control module 126 inputs the non-overlapping PWM control signal with a larger duty cycle to the power tube driving module 13 to prevent the power switch module 11 from overlapping in the on state and the off state, and turn on five switches at the same time, thereby reducing power consumption and improving efficiency.

[0075] That is, when the size of the sawtooth wave generated by the sawtooth wave generating circuit 121 remains unchanged, the output of the error amplifier 121 module changes with the output voltage, so the output of the first comparator 124 also changes with the output voltage and is input to the SR latch 125. The SR latch 125 inputs the output of the comparator to the dead time control circuit to generate a non-overlapping PWM control signal to the power driving module.

[0076] Compared with the current mirror circuit used in the current neural electrical stimulation circuit, the switching power supply circuit for neural electrical stimulation provided in the embodiment of the present invention uses an inductor to maintain a constant current, and the switch will not overlap when switching states, thereby improving the circuit efficiency.

[0077] In some embodiments of the present invention, the first comparator 124 performs a FB The voltage is compared with the reference voltage, and a square wave is generated according to the comparison result.

[0078] The SR latch 125 inputs the square wave to the dead time control module 126 according to the clock signal.

[0079] The dead time control module 126 generates a PWM control signal according to the square wave.

[0080] In some embodiments of the present invention, the error amplifier 121 includes a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, and an operational amplifier.

[0081] The second resistor R2 is connected in series with the second capacitor C2, and then connected in parallel with the first capacitor C1.

[0082] One end of the first resistor R1 is connected to the sampling voltage V FB The other end is connected to the inverting input terminal of the operational amplifier EA, one end of the first capacitor C1, and one end of the second resistor R2.

[0083] The non-inverting input of the operational amplifier EA is connected to the reference voltage V REF The operational amplifier samples the sampling voltage signal V from the first output voltage of the power switch module 11. FB and the reference voltage signal V REF The first resistor R1, the second resistor R2, the first capacitor C1 and the second capacitor C2 form a second type of compensation to determine the stable output of the operational amplifier EA.

[0084] In some embodiments of the present invention, the sawtooth wave generating circuit 121 includes a current source, a third capacitor C3, a switch, and a second comparator.

[0085] The current source charges the third capacitor C3 to control the rise of the sawtooth wave.

[0086] The second comparator controls the switch to be turned on, so as to control the third capacitor C3 to discharge, so as to control the decrease of the sawtooth wave.

[0087] Specifically, when the voltage on the third capacitor C3 is lower than the highest voltage of the sawtooth wave, the second comparator output controls the switch to be disconnected, the third capacitor C3 continues to be charged, and the sawtooth wave ramp voltage continues to rise; when the voltage on the third capacitor C3 reaches the highest voltage of the sawtooth wave, the second comparator output controls the switch to be turned on, the third capacitor C3 is discharged, and the voltage on the third capacitor C3 drops to zero, which is now in the falling state of the sawtooth wave, thereby generating a correct sawtooth wave.

[0088] In some embodiments of the present invention, Figure 4 As shown, the power tube driving module 13 includes a bidirectional level converter 132 and a driving circuit 131 . The bidirectional level converter 132 includes a high level converter and a low level converter. The driving circuit 131 includes a multi-stage inverter.

[0089] The low level converter is used to convert a square wave signal in a high voltage domain into a square wave signal in a low voltage domain.

[0090] The high level converter is used to convert a square wave signal in a low voltage domain into a square wave signal in a high voltage domain.

[0091] The driving circuit 131 is used to drive the load to ensure that the PWM signal output by the bidirectional level converter 132 can generate a corresponding voltage change at the gate of the switch tube.

[0092] The bidirectional level converter 132 combines a high level converter and a low level converter together, and can realize the square wave signal conversion from low level to high level and from high level to low level.

[0093] Specifically, the input end of the bidirectional level converter 132 is connected to the output end of the PWM control module 12. The bidirectional level converter 132 does not change the duty cycle of the PWM control signal, but changes the voltage domain of the PWM control signal. Among them, the high-level converter can detect the falling edge of the signal and generate a falling edge signal with a higher voltage domain, thereby increasing the voltage domain of the PWM wave. The low-level converter can detect the rising edge of the PWM wave and generate a rising edge signal with a lower voltage domain, thereby lowering the voltage domain of the PWM.

[0094] In addition, the bidirectional level converter 132 can detect the power tube source voltage V LX The change in voltage at the gate produces the same voltage change as the source, maintaining the voltage difference between the gate and the source of the power tube unchanged, preventing the power tube from being broken down.

[0095] The output end of the bidirectional level converter 132 is connected to the input end of the driving circuit 131. The driving circuit 131 can drive a larger load to ensure that the change of the PWM wave can cause the gate voltage of the power switch tube to change accordingly. A larger PWM wave will extend the on-state time of the power switch module 1111 and shorten the off-state time, making the output voltage higher. At the beginning, the output voltage is lower than the normal value, so the output voltage is raised back to the normal value through PWM wave regulation to maintain stability.

[0096] The switching power supply circuit for neural electrical stimulation provided in the embodiment of the present invention is an electrical stimulation circuit that can realize constant voltage and constant current stimulation, uses an inductor to realize constant current stimulation, does not use a current mirror circuit to reduce additional power consumption, and has higher efficiency than the current electrical stimulation circuit; by utilizing the characteristic that the voltage across the capacitor cannot change suddenly, it can realize positive voltage and negative voltage stimulation with the same charge amount, solving the charge balance problem; by using a high-voltage tube, the output voltage range is very large, and the adjustable range of the output voltage is larger than that of the current electrical stimulation circuit, solving the problems existing during high-impedance electrode stimulation; and because the potential of the flying capacitor connected to the output point has positive and negative voltages, the proportion of the time that the power switch is turned on is larger than that of the current switching power supply, solving the problem that the duty cycle of the switching power supply PWM control is too small.

[0097] The case where the output voltage becomes higher is similar to the case where the output voltage becomes lower as described above, and will not be described in detail here.

[0098] The above description is an embodiment provided by the present invention and does not limit the present invention in any form. Those skilled in the art can modify the present embodiment by using the technical content of the above description without departing from the scope of the technical solution of the present invention. Therefore, the general principles defined in this article can be implemented in other embodiments without departing from the spirit or scope of the present invention. The scope of protection of the present invention shall be based on the definition of the claims.

Claims

1. A switching power supply circuit for neural electrical stimulation, characterized in that: include: A power switch module, used for controlling the input voltage to periodically charge and discharge the output capacitor to form a first output voltage; A PWM control module, used for sampling the first output voltage and generating a PWM control signal according to a comparison result between the sampled value and a reference voltage; The power tube driving module is used to drive the power switch according to the PWM control signal to obtain a second output voltage for neural electrical stimulation.

2. The circuit according to claim 1, characterized in that The power switch module includes a switch tube module and a power output submodule; The switch tube module includes a plurality of switch tubes and a flying capacitor, and is used to control the on or off of the plurality of switch tubes; The power output submodule includes an inductor, a resistor and an output capacitor, and is used to output a first output voltage.

3. The circuit according to claim 2, characterized in that The switch tube module includes a first switch tube S1, a second switch tube S2, a third switch tube S3, a fourth switch tube S4, a fifth switch tube S5 and a flying capacitor C F The power output submodule includes an inductor L, an equivalent series resistor ESR, and an output resistor R O And the output capacitor C O ; The first terminal of the first switch tube S1 is connected to the input voltage V IN The second end is respectively connected to the first end of the second switch tube S2, the first end of the fifth switch tube S5, and the flying capacitor C F A first end is connected; The second end of the second switch tube S2 is connected to the first end of the third switch tube S3 and the first end of the inductor L respectively; The second end of the third switch tube S3 is respectively connected to the flying capacitor C F The second end of the switch tube S4 is connected to the first end of the switch tube S4; The second end of the inductor L is respectively connected to the first end of the equivalent series resistor ESR, the output resistor R O A first end is connected; The second end of the equivalent series resistor ESR is connected to the output capacitor C O The first end of the output capacitor C O The first end outputs a first output voltage V OUT .

4. The circuit according to claim 3, characterized in that When the first switch tube S1, the second switch tube S2, and the fourth switch tube S4 are in the on state, and the third switch tube S3 and the fifth switch tube S5 are in the off state, the input voltage V IN The output capacitor C O Charging; When the first switch tube S1, the second switch tube S2, and the fourth switch tube S4 are in the off state, and the third switch tube S3 and the fifth switch tube S5 are in the on state, the output capacitor C O Discharge.

5. The circuit according to claim 3, characterized in that The PWM control module includes an error amplifier, a sawtooth wave generating circuit and a PWM wave generating circuit; the PWM wave generating circuit includes a first comparator, an SR latch and a dead time control module; The inverting terminal of the error amplifier samples the voltage V FB , the in-phase terminal is connected to the reference voltage, and the output terminal is connected to the in-phase terminal of the first comparator; The inverting terminal of the first comparator is connected to the output terminal of the sawtooth wave generating circuit, and the output terminal is connected to the R terminal of the SR latch; The S terminal of the SR latch is connected to the output terminal of the sawtooth wave generating circuit, the output terminal is connected to the input terminal of the dead time control module, and the output terminal of the dead time control module is connected to the power tube driving module.

6. The circuit according to claim 5, characterized in that The first comparator detects the sampling voltage V FB comparing with the reference voltage and generating a square wave according to the comparison result; The SR latch inputs the square wave into the dead time control module according to the clock signal; The dead time control module generates a PWM control signal according to the square wave.

7. The circuit according to claim 5, characterized in that The error amplifier includes a second resistor R2, a first capacitor C1 and a second capacitor C2; The second resistor R2 is connected in series with the second capacitor C2, and then connected in parallel with the first capacitor C1.

8. The circuit according to claim 5, characterized in that The sawtooth wave generating circuit includes a current source, a third capacitor C3, a switch and a second comparator; The current source charges the third capacitor C3 to control the rise of the sawtooth wave; The second comparator controls the switch to be turned on, so as to control the third capacitor C3 to discharge, so as to control the decrease of the sawtooth wave.

9. The circuit according to claim 1, characterized in that The power tube driving module includes a bidirectional level converter and a driving circuit, the bidirectional level converter includes a high level converter and a low level converter, and the driving circuit includes a multi-stage inverter; The low level converter is used to convert the square wave signal in the high voltage domain into a square wave signal in the low voltage domain; The high level converter is used to convert the square wave signal in the low voltage domain into a square wave signal in the high voltage domain; The driving circuit is used to drive the load to ensure that the PWM signal output by the bidirectional level converter can generate a corresponding voltage change at the gate of the switch tube.

Images