Low-noise pressure stabilization control circuit

Abstract

The utility model relates to the technical field of electronics, in particular to a low-noise pressure stabilization control circuit, which can reduce control cost and comprises a voltage division circuit used for generating a target voltage value; the comparison circuit is used for generating a control signal by utilizing a comparator; the signal amplification circuit is used for amplifying a sensor signal; and the pump driving circuit is used for controlling and driving the sucking pump.

Description

Technical Field

[0001] The utility model relates to the technical field of electronics, in particular to a low-noise pressure stabilization control circuit. Background Art

[0002] Flow cytometers belong to the field of in vitro diagnostic equipment and are used for biochemical analysis. The fluid system of a flow cytometer often needs to maintain a stable internal pressure to push the sheath fluid and sample steadily through the flow chamber.

[0003] At present, the pressure maintenance of the fluid system is usually maintained by forming a closed-loop control using a vacuum pump and a pressure sensor. Common control methods include CPU programmable control, in which the CPU obtains the pressure sensor information, outputs a pump control signal according to the algorithm calculation, controls the pump suction, and achieves pressure maintenance. The CPU programmable control occupies CPU overhead, has high cost, and is complex to implement. Summary of the invention

[0004] In order to solve the problem of high control cost of the existing CPU, the utility model provides a low-noise pressure stabilization control circuit, which can reduce the control cost.

[0005] The technical solution is as follows: a low-noise pressure stabilization control circuit, characterized in that it includes:

[0006] A voltage divider circuit for generating a target voltage value;

[0007] A comparison circuit, using a comparator to generate a control signal;

[0008] A signal amplifying circuit, used for amplifying the sensor signal;

[0009] The pump driving circuit is used to control and drive the air pump.

[0010] It is further characterized in that the voltage divider circuit comprises a resistor R4 and a resistor R5, one end of the resistor R4 is connected to the power supply VCC2, the other end is connected in series with the resistor R5, and outputs a voltage divider signal, the other end of the resistor R5 is connected to the power supply ground, and both ends of the resistor R5 are connected in parallel with the capacitor C1;

[0011] The signal amplification circuit includes an amplifier U3, a resistor R7, a capacitor C4 and a capacitor C5, the resistor R7 is connected between the gain adjustment terminals RG1 and RG2 of the amplifier U3, the input IN- and the input IN+ are connected to the sensor and connected to both ends of the capacitor C4, the negative power supply terminal V- of the amplifier U3 is connected to the reference setting terminal REF and connected to the power supply ground GND, the output Vout terminal is connected to the power supply ground GND through the capacitor C5, and the positive power supply terminal V+ is connected to the power supply VCC;

[0012] The comparison circuit includes a comparator U1 and resistors R1, R2, and R3, the negative input IN- of the comparator U1 inputs the voltage division signal, the positive input IN+ of the comparator U1 and the output Out are connected through the resistor R2, and the output Out port and the power supply VCC are connected through the resistor R3, the output Out port outputs a control signal, the positive input IN+ of the comparator U1 is also connected to the output Vout terminal of the amplifier U3 through the resistor R1, the power supply terminal VCC of the comparator U1 is connected to the power supply VCC, and the negative power supply terminal VEE is connected to the power ground GND;

[0013] The driving circuit includes an H-bridge driving chip U2, a resistor R6 and capacitors C2 and C3. The input terminal IN1 of the H-bridge driving chip U2 inputs the control signal, the input terminal IN2 is connected to the power ground GND, the reference voltage VREF terminal is connected to the power supply VCC1 and is connected to the power ground GND through the capacitor C2, the GND port of the H-bridge driving chip U2 is connected to the power ground GND, the RS port is connected to the power ground GND through the resistor R6, the VM terminal is connected to the power supply VCCM and is connected to the power ground GND through the capacitor C3, and the output terminals OUT1 and OUT2 are connected to the vacuum pump.

[0014] After adopting the utility model, there is no need for CPU to perform algorithm control, and closed-loop control can be directly realized by hardware. The comparator compares the target pressure signal and the pressure monitoring signal, and outputs a control signal when a difference occurs to start or shut down the air pump. The circuit structure is simple and the implementation cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the circuit schematic diagram of the utility model;

[0016] Figure 2 This is a circuit diagram for the specific implementation of the utility model. DETAILED DESCRIPTION

[0017] See Figure 1 , Figure 2 As shown, a low-noise pressure stabilization control circuit comprises:

[0018] A voltage divider circuit for generating a target voltage value;

[0019] Comparison circuit, using comparator to generate control signal, combined with configuration resistor to form hysteresis comparison window

[0020] A signal amplifying circuit, used for amplifying the sensor signal;

[0021] The pump driving circuit is used to control and drive the air pump.

[0022] Specifically, the voltage divider circuit includes resistors R4 and R5, one end of the resistor R4 is connected to the power supply VCC2, the other end is connected in series with the resistor R5, and a voltage divider signal is output, marked as V_Target, the other end of the resistor R5 is connected to the power ground, and both ends of the resistor R5 are connected in parallel with the capacitor C1, C1 is beneficial to reduce the voltage divider signal noise, V_Target voltage value is (VCC2) * R5 / (R4 + R5), wherein R4 is a 50K, 1% precision resistor, R5 is a 21.5K, 1% precision resistor, C1 is a 1uF capacitor, and VCC2 is 5V.

[0023] The signal amplification circuit includes an amplifier U3, a resistor R7, a capacitor C4 and a capacitor C5. A resistor R7 is connected between the gain adjustment terminals RG1 and RG2 of the amplifier U3. Different values ​​of R7 can configure different signal amplification factors. The input IN- is connected to the positive terminal of the sensor output and is marked as Sensor+. The input IN+ is connected to the negative terminal of the sensor output and is marked as Sensor-. IN- and IN+ are connected through a capacitor C4. C4 can remove part of the noise in the touch sensor. The negative power terminal V- of the amplifier U3 is connected to the reference setting terminal REF and connected to the power ground GND. The output Vout terminal signal is marked as V_signal and is connected to the power ground GND through a capacitor C5. C5 further attenuates the noise in the amplified V_signal. The positive power terminal V+ is connected to the power supply VCC. U3 selects TI's INA126 instrument amplifier. The power supply VCC is 5V. The capacitors C4 and C5 are selected as 0.1uf. The R7 value selects a 0.1% precision resistor, 4.02k, and the signal is amplified 25 times.

[0024] The comparison circuit includes a comparator U1 and resistors R1, R2, and R3. The negative input IN- of the comparator U1 inputs a voltage division signal V_Target. The positive input IN+ of the comparator U1 and the output Out are connected via a resistor R2, and the output Out port and the power supply VCC are connected via a resistor R3. The output Out port outputs a control signal V_Control for a subsequent control pump drive circuit. The positive input IN+ of the comparator U1 is also connected to the output Vout terminal of the amplifier U3 via a resistor R1. The power supply terminal VCC of the comparator U1 is connected to the power supply VCC, and the negative power supply terminal VEE is connected to the power ground GND. During operation, when the pressure sensor monitoring signal V_Signal is lower than the set value VL, the comparator outputs the level Vo_H at the Out port, controls the vacuum pump to start working, and the pressure approaches the target pressure. When the pressure sensor monitoring signal V_Signal is higher than the set value VH, the comparator outputs the low level close to 0 at the Out port, controls the vacuum pump to stop working, and as the system pressure gradually deviates to maintain the target, when the pressure sensor monitoring signal V_Signal is lower than VL again, the vacuum pump starts again. During operation, the pump starts when the system pressure is lower than the lower limit of the interval, and stops when it is higher than the upper limit of the interval. VH, VL and R1, R2 and R3 follow the following relationship:

[0025] V_Target=VH*(R2 / (R1+R2)),

[0026] V_Target=VL*((R2+R3) / (R1+R2+R3))+ VCC1*(R1 / (R1+R2+R3)).

[0027] The driving circuit includes an H-bridge driving chip U2, a resistor R6 and capacitors C2 and C3. The input terminal IN1 of the H-bridge driving chip U2 inputs a control signal V_control, the input terminal IN2 is connected to the power ground GND, the reference voltage VREF terminal is connected to the power supply VCC1 and is connected to the power ground GND through the capacitor C2. The GND port of the H-bridge driving chip U2 is connected to the power ground GND, and the RS port is connected to the power ground GND through the resistor R6. The resistor R6 and VCC1 jointly determine the maximum pump output current, which can limit the impact of excessive current on the power supply and noise generation when the pump starts. The VM terminal is connected to the power supply VCCM and is connected to the power ground GND through the capacitor C3. The output terminal OUT1 is connected to the positive port of the pump marked as Pump+, and the output terminal OUT2 is connected to the negative port of the pump marked as Pump-. Specifically, U2 selects TI's DRV8831DSGR chip, VCCM power supply is 24V, VCC1 is 5V, C2 is 0.1u, R6 is 0.18R resistor, C3 is 1u capacitor, the maximum current satisfies the relationship VCC1 / (10*R6), and the maximum pump current is 2.7A.

[0028] In the present application, a comparator is used to compare the target pressure signal and the pressure monitoring signal, and when a difference occurs, a control signal is output to start or shut down the vacuum pump to maintain pressure stability.

Claims

1. A low-noise pressure stabilization control circuit, characterized in that: include: A voltage divider circuit for generating a target voltage value; A comparison circuit, using a comparator to generate a control signal; A signal amplifying circuit, used for amplifying the sensor signal; The pump driving circuit is used to control and drive the air pump.

2. A low-noise pressure stabilization control circuit according to claim 1, characterized in that: The voltage divider circuit includes resistor R4 and resistor R5, one end of the resistor R4 is connected to the power supply VCC2, the other end is connected in series with the resistor R5, and outputs a voltage divider signal, the other end of the resistor R5 is connected to the power ground, and both ends of the resistor R5 are connected in parallel with the capacitor C1.

3. A low-noise pressure stabilization control circuit according to claim 2, characterized in that: The signal amplification circuit includes an amplifier U3, a resistor R7, a capacitor C4 and a capacitor C5. The resistor R7 is connected between the gain adjustment terminals RG1 and RG2 of the amplifier U3, the input IN- and the input IN+ are connected to the sensor and are connected to both ends of the capacitor C4, the negative power supply terminal V- of the amplifier U3 is connected to the reference setting terminal REF and to the power supply ground GND, the output Vout terminal is connected to the power supply ground GND through the capacitor C5, and the positive power supply terminal V+ is connected to the power supply VCC.

4. A low-noise pressure stabilization control circuit according to claim 3, characterized in that: The comparison circuit includes a comparator U1 and resistors R1, R2, and R3. The negative input IN- of the comparator U1 inputs the voltage division signal. The positive input IN+ of the comparator U1 and the output Out are connected through the resistor R2, and the output Out port and the power supply VCC are connected through the resistor R3. The output Out port outputs a control signal. The positive input IN+ of the comparator U1 is also connected to the output Vout terminal of the amplifier U3 through the resistor R1. The power supply terminal VCC of the comparator U1 is connected to the power supply VCC, and the negative power supply terminal VEE is connected to the power ground GND.

5. A low-noise pressure stabilization control circuit according to claim 4, characterized in that: The driving circuit includes an H-bridge driving chip U2, a resistor R6 and capacitors C2 and C3. The input terminal IN1 of the H-bridge driving chip U2 inputs the control signal, the input terminal IN2 is connected to the power ground GND, the reference voltage VREF terminal is connected to the power supply VCC1 and is connected to the power ground GND through the capacitor C2, the GND port of the H-bridge driving chip U2 is connected to the power ground GND, the RS port is connected to the power ground GND through the resistor R6, the VM terminal is connected to the power supply VCCM and is connected to the power ground GND through the capacitor C3, and the output terminals OUT1 and OUT2 are connected to the vacuum pump.

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