CN215528857U

CN215528857U - MOS control circuit with optical coupling isolation

Info

Publication number: CN215528857U
Application number: CN202121619970.1U
Authority: CN
Inventors: 郑剑锋; 祝新军; 朱明�
Original assignee: Hangzhou H&t Intelligent Control Technology Co ltd
Current assignee: Hangzhou H&t Intelligent Control Technology Co ltd
Priority date: 2021-07-15
Filing date: 2021-07-15
Publication date: 2022-01-14
Anticipated expiration: 2031-07-15

Abstract

The utility model discloses an MOS control circuit with optical coupling isolation, which comprises a low-voltage control circuit, a high-voltage drive circuit, an MCU drive unit and an optical coupling isolator, wherein the low-voltage control circuit is connected with the high-voltage drive circuit through the optical coupling isolator and receives a drive signal of the MCU drive unit. The utility model provides an MOS control circuit with optical coupling isolation, wherein a voltage-stabilizing tube is connected in parallel at the front end of the secondary stage of an optical coupling isolator in a circuit formed by connecting a divider resistor and the optical coupling isolator in series, the voltage-stabilizing tube with the corresponding voltage grade is broken down by the voltage obtained by the voltage-dividing circuit, and the leakage current passing through the optical coupling isolator can be bypassed after the voltage-stabilizing tube is conducted. When the low-voltage MCU sends an instruction to control the conduction of the optical coupling isolator, the driving voltage established after the voltage is stabilized by the voltage stabilizing tube drives the power device N-MOSFET through the optical coupling isolator, so that the low-voltage MCU controls the high-voltage circuit through the optical coupling isolator.

Description

MOS control circuit with optical coupling isolation

Technical Field

The utility model relates to the field of electronic circuits, in particular to an MOS control circuit with optical coupling isolation.

Background

At present, most household electrical appliances obtain direct-current high voltage of about 310V through rectification by alternating-current mains supply, the direct-current high voltage of 310V can be used for supplying power to a switching power supply, and other related loads such as a motor and a UV lamp can also be used for supplying power. But the power supply of the switching power supply cannot be cut off, otherwise, the intelligent control of the product cannot be realized. The product will have a requirement for reduced power consumption, and it will be necessary to disconnect 310V loads other than the switching power supply. At this moment, the optocoupler is needed to be used for realizing the control of the low voltage to the high-voltage end load, and the effect of reducing the standby power consumption is achieved. The driving of the power device N-MOSFET needs to consider the problem of driving voltage, and needs to consider the problems of driving voltage and system voltage field. If a winding is separately driven from the switching power supply, the power of the switching voltage is increased, and the power of a transformer or a switching chip may need to be increased, so that the cost of the product is increased. And the driving power source may have a long wire to the power device, which is also not favorable for the layout of the PCB.

For example, the present invention relates to a power control drive circuit which is disclosed in chinese patent document "CN 105099420A" and in which the on/off time of a controlled power control device (MOSFET or IGBT) can be made short and the drive current can be made sufficiently large. It includes: the drive circuit front stage is used for controlling the output voltage of the voltage output end of the drive circuit according to a PWM signal or a logic signal sent from the outside; the grid electrode of the N-MOSFET is connected with the voltage output end of the front stage of the driving circuit; a first resistor is arranged between the grid electrode and the source electrode of the N-MOSFET, and the drain electrode of the N-MOSFET is connected with a driving power supply; the grid electrode of the P-MOSFET is connected with the voltage output end of the drive integrated circuit; a second resistor is arranged between the source electrode of the N-MOSFET and the source electrode of the P-MOSFET; and the grid electrode of the controlled power control device is connected with the third resistor in series and then is connected with the source electrode of the P-MOSFET, and the source electrode of the controlled power control device is connected with the drain electrode of the P-MOSFET.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the problem that a low-voltage MCU is difficult to conveniently control a high-voltage circuit. The utility model provides a take MOS control circuit of opto-coupler isolation, through in the circuit that divider resistance and opto-coupler isolator establish ties, connect a stabilivolt in parallel at the secondary front end of opto-coupler isolator, the stabilivolt of the corresponding voltage grade of voltage breakdown that obtains through the bleeder circuit, can bypass the leakage current that passes through the opto-coupler isolator after stabilivolt switches on. When the low-voltage MCU sends an instruction to control the conduction of the optical coupling isolator, the driving voltage established after the voltage is stabilized by the voltage stabilizing tube drives the power device N-MOSFET through the optical coupling isolator, so that the low-voltage MCU controls the high-voltage circuit through the optical coupling isolator.

In order to achieve the purpose, the utility model adopts the following technical scheme: the utility model provides a take MOS control circuit of opto-coupler isolation, characterized by, includes low voltage control circuit, high voltage drive circuit, MCU drive unit and opto-coupler isolator, high voltage drive circuit is connected through the opto-coupler isolator to low voltage control circuit, low voltage control circuit receives MCU drive unit drive signal. The MCU drive unit is specifically selected according to actual conditions, the low-voltage control circuit and the high-voltage drive circuit act together, and the drive voltage required by the power device N-MOSFET is obtained through the circuit, so that the problem that the low-voltage MCU controls the power device N-MOSFET through the optocoupler isolator can be solved, meanwhile, the cost can be reduced through a simple circuit, the power can be obtained on the spot, and the PCB layout is simple.

Preferably, the low-voltage control circuit comprises a resistor R35, a resistor R37, a resistor R39 and a transistor Q3, wherein a first end of the resistor R37 is connected with the MCU driving unit, a second end of the resistor R37 is respectively connected with a base of the transistor Q3 and a first end of the resistor R39, a second end of the resistor R39 is grounded, a collector of the transistor Q3 is connected with a negative electrode of an emitter of the optocoupler PC5, a positive electrode of the emitter of the optocoupler PC5 is connected with a first end of the resistor R35, a second end of the resistor R35 is connected with a power supply, and an emitter of the transistor Q3 is grounded. In the low-voltage control circuit, the transistor Q3 is used to amplify a weak driving signal into an electrical signal with a large amplitude value.

Preferably, the high-voltage driving circuit comprises a resistor R33, a resistor R34, a resistor R38, a resistor R40, a zener diode D8 and a power switch tube Q5, wherein a first end of the resistor R33 is connected with a direct-current voltage, a second end of the resistor R34 is respectively connected with a first end of the resistor R35, a negative electrode of the zener diode D8, a second end of the resistor R34 is connected with a C electrode of a receiving end of the optocoupler isolator PC5, an E electrode of the receiving end of the optocoupler isolator PC5 is connected with a first end of the resistor R38, a second end of the resistor R38 is connected with a gate of the power switch tube Q5, an anode of the zener diode D8 is respectively connected with the first end of the resistor D40 and the ground, a second end of the resistor R40 is connected with a source of the power switch tube Q5, and a source and a drain of the power switch tube Q5 are grounded. In the high-voltage driving circuit, a resistor R33, a resistor R34, a resistor R38 and a resistor R40 are voltage dividing resistors, high-voltage direct current is connected with the secondary side of an optical coupler isolator PC5 in series through the voltage dividing resistors R33, R34, R38 and R40, a voltage stabilizing diode D8 is connected in parallel at the fourth pin of the optical coupler isolator PC5, in the selection of the voltage dividing resistors, the value of R33 is relatively large, high voltage resistance is required, and the resistor R38 can be used as the driving resistor of a power device N-MOSFET and is smaller in value.

Preferably, the optical coupler isolator PC5 is used to electrically isolate the high voltage driving circuit from the low voltage control circuit. The optical coupler isolator is used for preventing interference caused by electric connection between the low-voltage control circuit and the high-voltage driving circuit.

Preferably, the voltage of the zener diode D8 cannot exceed the driving voltage of the power device N-MOSFET, which is the power switch Q5 in the circuit. Usually, the voltage division value of the whole circuit is slightly lower than the voltage division value of the resistor R38 and the resistor R40 which are connected in series, and the voltage division value of the resistor enables the voltage of the resistor to effectively break down the voltage stabilizing diode, so that the driving voltage of the driving power N-MOSFET is obtained.

Preferably, the resistor R39 is a pull-down resistor at the base of the transistor Q3, and is connected in parallel with the base of the transistor Q3. Because the base of the triode can not be directly grounded, a pull-down resistor is needed to be grounded, otherwise, the input signal is distorted.

Preferably, the dc voltage is obtained by rectifying ac mains power, specifically 310V.

Therefore, the utility model has the following beneficial effects:

1. the driving voltage suitable for driving the power N-MOSFET is obtained through the simple discrete device, and the low-voltage MCU is convenient to control a high-voltage circuit through the optocoupler isolator;

2. simple and discrete devices, and reduced material cost.

Drawings

Fig. 1 is a circuit diagram of a MOS control circuit with optical coupling isolation according to the present invention.

Detailed Description

The embodiment provides a MOS control circuit with optical coupling isolation. Referring to fig. 1, a low voltage control circuit 1 is connected to a high voltage driving circuit 2 through an optical coupler isolator, and the low voltage control circuit 1 receives a driving signal of an MCU driving unit. The low-voltage control circuit 1 comprises a resistor R35, a resistor R37, a resistor R39 and a triode Q3, wherein the first end of the resistor R37 is connected with the driving unit, the second end of the resistor R37 is respectively connected with the base of the triode Q3 and the first end of the resistor R39, the second end of the resistor R39 is grounded, the collector of the triode Q3 is connected with the cathode of the emitter of the optocoupler PC5, the anode of the emitter of the optocoupler PC5 is connected with the first end of the resistor R35, the second end of the resistor R35 is connected with a power supply, and the emitter of the triode Q3 is grounded.

The high-voltage driving circuit 2 comprises a resistor R33, a resistor R34, a resistor R38, a resistor R40, a zener diode D8 and a power switch tube Q5, wherein the first end of the resistor R33 is connected with direct-current voltage, the second end of the resistor R34 is respectively connected with the first end of a resistor R35, the negative electrode of the zener diode D8, the second end of the resistor R34 is connected with the C electrode of the receiving end of an optocoupler isolator PC5, the E electrode of the receiving end of the optocoupler isolator PC5 is connected with the first end of the resistor R38, the second end of the resistor R38 is connected with the grid of the power switch tube Q5, the positive electrode of the zener diode D8 is respectively connected with the first end of the resistor D40 and the ground, the second end of the resistor R40 is connected with the source electrode of the power switch tube Q5, and the source electrode and the drain electrode of the power switch tube Q5 are grounded. The resistor R39 is a pull-down resistor of the base of the triode Q3 and is connected in parallel with the base of the triode Q3. The direct current voltage is obtained by rectifying alternating current commercial power, and is specifically 310V. The direct current voltage is obtained by rectifying alternating current commercial power, and is specifically 310V.

Low-voltage control circuit 1: after the electric signal of the MCU driving unit is transmitted, the electric signal passes through the optocoupler isolator PC5 after being amplified by the triode Q3, and the process is convenient and easy to operate. The resistors R35 and R37 are protection resistors, the resistor R39 is a pull-down resistor of the base electrode of the triode, and the pull-down resistor is grounded to better play a role in terminating.

High-voltage drive circuit 2: alternating current mains supply is rectified to obtain high-voltage direct current of about 310V, the high-voltage direct current passes through voltage division resistors R33, R34, R38 and R40 and the secondary side of an optical coupling isolator PC5 in series, a voltage stabilizing diode D8 is connected in parallel with a C pole at the receiving end of the optical coupling isolator PC5, the voltage of the diode cannot exceed the driving voltage of a power device N-MOSFET, a voltage division value of a resistor R38 and a resistor R40 which are connected in series in the whole circuit is usually selected to be slightly lower, and the value can enable the resistor voltage division voltage to effectively break down the voltage stabilizing diode D8, so that the driving voltage of the driving power N-MOSFET is obtained. In the selection of the divider resistor, the value of the resistor R33 is relatively large and needs to resist high voltage, and the value of the resistor R38 can be smaller as the driving resistor of the N-MOSFET of the power device.

Claims

1. The utility model provides a take MOS control circuit of opto-coupler isolation, characterized by, includes low voltage control circuit (1), high voltage drive circuit (2), MCU drive unit and opto-coupler isolator, high voltage drive circuit (2) are connected through the opto-coupler isolator in low voltage control circuit (1), MCU drive unit drive signal is received in low voltage control circuit (1).

2. The MOS control circuit with optical isolator according to claim 1, wherein the low voltage control circuit (1) comprises a resistor R35, a resistor R37, a resistor R39 and a transistor Q3, a first end of the resistor R37 is connected with the MCU driving unit, a second end of the resistor R37 is connected with a base of the transistor Q3 and a first end of the resistor R39 respectively, a second end of the resistor R39 is grounded, a collector of the transistor Q3 is connected with a negative electrode of an emitter of the optical isolator PC5, a positive electrode of the emitter of the optical isolator PC5 is connected with a first end of the resistor R35, a second end of the resistor R35 is connected with a power supply, and an emitter of the transistor Q3 is grounded.

3. The MOS control circuit with optical coupling isolation according to claim 1, wherein the high voltage driving circuit (2) comprises a resistor R33, a resistor R34, a resistor R38, a resistor R40, a zener diode D8 and a power switch tube Q5, wherein a first end of the resistor R33 is connected with a direct current voltage, a second end of the resistor R34 is respectively connected with a first end of a resistor R35, a negative electrode of a zener diode D8, a second end of the resistor R34 is connected with a C electrode of a receiving end of an optical coupling isolator PC5, an E electrode of the receiving end of the opto coupling isolator PC5 is connected with a first end of a resistor R38, a second end of the R38 is connected with a grid electrode of a power switch tube Q5, a positive electrode of the zener diode D8 is respectively connected with the first end of the resistor D40 and the ground, a second end of the resistor R40 is connected with a source electrode of the power switch tube Q5, and a source electrode and a drain electrode of the power switch tube Q5 are grounded.

4. An MOS control circuit with optical coupling isolation according to claim 2, wherein the optical coupling isolator PC5 is used for completing the electrical isolation between the high-voltage driving circuit (2) and the low-voltage control circuit (1).

5. The MOS control circuit with optical-coupling isolation as claimed in claim 3, wherein the voltage of the Zener diode D8 cannot exceed the driving voltage of the power device N-MOSFET, which is the power switch tube Q5 in the circuit.

6. The MOS control circuit with opto-isolator according to claim 2, wherein said resistor R39 is a pull-down resistor at the base of transistor Q3, connected in parallel with the base of transistor Q3.

7. The MOS control circuit with optical coupling isolation according to claim 3, wherein the DC voltage is obtained by rectifying AC commercial power, specifically 310V.