TW201513557A - Electronic device and fan driving circuit thereof - Google Patents

Abstract

An electronic device and fan control circuit thereof are provided. The fan control circuit includes a MCU, an interface, a first resistance, a field effect transistor, a voltage regulator tube, and a first capacitance. The gate of the field effect transistor is connected with the MCU, and is grounded through the first resistance. The source of the field effect transistor is grounded. The drain of the field effect transistor is connected with anode of the voltage regulator tube. The cathode of the voltage regulator tube is connected with the positive terminal of a fan and one end of the first capacitance. The other end of the first capacitance and the negative terminal of the fan are grounded. When PWM signal generated by the MCU is low, the field effect transistor is turned off, the voltage regulator tube is turned on, power source connected by the interface provides power to the fan, and the first capacitance is charged, thereby controlling the speed of the fan.

Description

Electronic device and fan drive circuit thereof

The present invention relates to an electronic device and a fan drive circuit thereof, and more particularly to an electronic device that uses a simple structure to drive a fan and a fan drive circuit thereof.

Current portable electronic devices use a boost circuit and a PWM control circuit to drive the speed of the fan. As shown in FIG. 1, it is a circuit configuration diagram of a fan drive circuit in the conventional electronic device 1. The electronic device 1 includes a booster circuit 10, a pulse width modulation PWM control circuit 20, and a fan 30. The booster circuit 10 is used to boost the operating voltage of the voltage source, typically from 5V to 12V, and provides a 12V operating voltage to the PWM control circuit 20. The PWM control circuit 20 is connected between the fan and the booster circuit 10 for receiving the operating voltage of the output of the booster circuit 10 to generate a PWM signal to control the rotation of the fan 30. Specifically, the PWM control circuit 20 includes a micro control unit (MCU) 201, a first resistor 202, a first transistor 203, a second resistor 204, a second transistor 205, and a third resistor. 206, a fourth resistor 207, a first capacitor 208 and a second capacitor 209. The base of the first transistor 203 is connected to the MCU 201 through the first resistor 202. The emitter of the first transistor 203 is grounded, and the collector is connected to the base electrode of the second transistor 205 and one end of the first capacitor 208 through the second resistor 204. The base of the second transistor 205 is also connected to the booster circuit 10 through a fourth resistor 207. The other end of the first capacitor 208 is grounded. The emitter of the second transistor 205 is connected to the fan 30, and the collector is connected to the booster circuit 10 through the third resistor 206. One end of the second capacitor 209 is connected to the emitter electrode of the second transistor 205, and the other end is grounded.

In operation, the MCU 201 generates a PWM signal having a fixed duty ratio. When the PWM signal is at a high level, the first transistor 203 is turned on, and the base electrode of the second transistor 205 is at a high level, thereby making the second three The pole tube 205 is turned on, the operating voltage generated by the boosting circuit 10 charges the second capacitor 209 through the second transistor, and provides an operating voltage to the fan 30, and controls the fan 30 to rotate, with the charging time of the second capacitor 209. The operating voltage of the fan 30 is increased to control the rotational speed of the fan 30; and when the PWM signal is low, the first transistor 203 is turned off, and the base electrode voltage of the second transistor 205 is the same as the emitter voltage, thereby The second transistor 205 is turned off, thereby controlling the fan 30 to stop rotating. However, in the prior art, the special booster circuit 10 required to control the rotation and the rotational speed of the fan 30 has a complicated structure and an increased cost.

In view of the above, it is desirable to provide an electronic device and a fan drive circuit therefor.

A fan driving circuit for controlling rotation and rotation speed of a fan, comprising a micro control unit MCU and a power supply interface, the MCU is configured to generate a PWM signal with a fixed duty ratio, and the power interface is used for connecting a power supply voltage . The fan driving circuit further includes a first resistor, a field effect transistor, a first Zener diode, and a first capacitor. The gate of the FET is connected to the MCU, and is also grounded through the first resistor, the source of the FET. The pole is grounded, the drain is connected to the anode of the first Zener tube and is connected to the voltage ,. The cathode of the first Zener tube is connected to the positive end of the fan and one end of the first capacitor, the other end of the first capacitor and the negative of the fan Extremely grounded, wherein when the PWM signal generated by the MCU is low, the FET is turned off, and the power supply voltage connected to the power supply interface is output to the anode of the first Zener diode to control the conduction of the first Zener diode, the power supply The power supply voltage of the interface is connected to the fan through the first voltage regulator to rotate the fan, and at the same time, the first capacitor is charged, and the operating voltage of the fan is increased as the charging time of the first capacitor increases. Control the speed of the fan.

An electronic device includes a power source, a fan driving circuit and a fan. The fan driving circuit is configured to control a rotation and a rotation speed of a fan, and includes a micro control unit MCU and a power supply interface. The MCU is used to generate a fixed occupation. An analog PWM signal that is used to connect to the supply voltage. The fan driving circuit further includes a first resistor, a field effect transistor, a first Zener diode, and a first capacitor. The gate of the FET is connected to the MCU, and is also grounded through the first resistor, the source of the FET. The pole is grounded, the drain is connected to the anode of the first Zener tube and is connected to the voltage ,. The cathode of the first Zener tube is connected to the positive end of the fan and one end of the first capacitor, the other end of the first capacitor and the negative of the fan Extremely grounded, wherein when the PWM signal generated by the MCU is low, the FET is turned off, and the power supply voltage connected to the power supply interface is output to the anode of the first Zener diode to control the conduction of the first Zener diode, the power supply The power supply voltage of the interface is connected to the fan through the first voltage regulator to rotate the fan, and at the same time, the first capacitor is charged, and the operating voltage of the fan is increased as the charging time of the first capacitor increases. Control the speed of the fan.

The electronic device and the fan driving circuit thereof of the present invention use a simple structure to drive the fan, thereby saving cost.

1 is a circuit configuration diagram of a conventional fan drive circuit.

2 is a circuit configuration diagram of an electronic device having a fan drive circuit in a preferred embodiment of the present invention.

Please refer to FIG. 2, which is a circuit diagram of an electronic device 1' having a fan driving circuit according to a preferred embodiment of the present invention. The electronic device 1' includes a fan 30 and a fan drive circuit 40. The fan drive circuit 40 is for controlling the rotation and the rotational speed of the fan 30. Specifically, the model number of the fan is CN703.

The fan driving circuit 40 includes a power supply interface 400, an MCU (micro control unit) 401, a first resistor 402, a field effect transistor 403, a first voltage regulator 405, and a first capacitor 406.

The gate of the FET 403 is connected to the MCU 401 while also being grounded through the first resistor 402. The source of the FET 403 is grounded, and the drain is connected to the anode of the first Zener 405 while being electrically connected to the power interface 400. The cathode of the first Zener diode 405 is connected to the positive terminal 301 of the fan 30 and one end of the first capacitor 406. The other end of the first capacitor 406 and the negative terminal 302 of the fan 30 are grounded. The power interface 400 is used to access the power supply voltage Vcc. Specifically, the power interface 400 can be connected to a battery to obtain a power voltage, and the power interface 400 can also be connected to the power adapter to obtain a power voltage.

In the present embodiment, the field effect transistor 403 is an N-type field effect transistor.

In operation, the MCU 401 generates a PWM signal having a fixed duty cycle, and when the PWM signal is low, the FET 403 is turned off. The power supply terminal Vcc connected to the power interface 400 is output to the anode of the first voltage regulator 405 to control the first voltage regulator 405 to be turned on, and the power voltage Vcc is then supplied to the fan 30 through the first voltage regulator 405. The fan 30 is rotated while charging the first capacitor 406, and the operating voltage of the fan 30 is increased as the charging time of the first capacitor 406 is increased, thereby controlling the rotational speed of the fan 30. When the PWM signal is at a high level, the FET 403 is turned on, so that the anode of the first Zener 405 is grounded through the turned-on FET 403, the first Zener 405 is turned off, and the power interface 400 is connected. The power supply voltage Vcc stops supplying power to the fan 30, causing the fan 30 to stop rotating.

The reverse-cut function of the first Zener diode 405 causes the first capacitor 406 to be discharged through the first Zener diode 405 when the PWM signal is low, so that the first capacitor 406 can only continue to discharge to the fan 30 and to the fan 30. powered by.

The fan driving circuit 40 further includes a diode 407 and a second voltage regulator 408. The anode of the diode 407 is connected to the cathode of the first Zener diode 405, and the cathode is connected to the cathode of the second Zener diode 408. The anode of the second Zener diode 408 is grounded. The diode 407 and the second Zener diode 408 have a bidirectional cut-off function, and the first capacitor 406 regulates the voltage output from the first capacitor 406 when the PWM signal is supplied to the fan 30 when the PWM signal is low.

Since the first capacitor 406 can not be discharged through the first Zener diode 405 when the PWM signal is low, only the power of the fan 30 can be increased, so that the power of the first capacitor 406 is accumulated, thereby increasing the operating voltage of the fan 30. Thereby the wind speed of the fan 30 is controlled.

The fan drive circuit 40 further includes a second capacitor 409. The second capacitor 409 has one end connected to the power interface 400 and the other end grounded for filtering the power supply voltage and current connected to the power interface 400.

Compared with FIG. 1, the fan drive circuit 40 does not require a special booster circuit to increase the operating voltage of the fan 30 and control the rotation and rotational speed of the fan 30.

1,1’‧‧‧Electronic devices

10‧‧‧Boost circuit

20‧‧‧PWM control circuit

30‧‧‧Fan

201‧‧‧MCU

202‧‧‧First resistance

203‧‧‧ first triode

204‧‧‧second resistance

205‧‧‧second triode

206‧‧‧ Third resistor

207‧‧‧fourth resistor

208‧‧‧first capacitor

209‧‧‧second capacitor

40‧‧‧Fan drive circuit

400‧‧‧Power interface

401‧‧MCU

402‧‧‧First resistance

403‧‧‧ FET

405‧‧‧First Zener

406‧‧‧first capacitor

407‧‧‧dipole

408‧‧‧Second voltage regulator

409‧‧‧second capacitor

301‧‧‧ positive end

302‧‧‧Negative end

no

1'‧‧‧Electronic device

30‧‧‧Fan

40‧‧‧Fan drive circuit

400‧‧‧Power interface

401‧‧MCU

402‧‧‧First resistance

403‧‧‧ FET

405‧‧‧First Zener

406‧‧‧first capacitor

407‧‧‧dipole

408‧‧‧Second voltage regulator

409‧‧‧second capacitor

301‧‧‧ positive end

302‧‧‧Negative end

Claims (10)

A fan driving circuit for controlling rotation and rotation speed of a fan, comprising a micro control unit MCU and a power supply interface, the MCU is configured to generate a PWM signal with a fixed duty ratio, and the power interface is used for connecting a power supply voltage The improvement is that
The fan driving circuit further includes a first resistor, a field effect transistor, a first Zener diode, and a first capacitor. The gate of the FET is connected to the MCU, and is also grounded through the first resistor, the source of the FET. The pole is grounded, the drain is connected to the anode of the first Zener tube and is connected to the voltage ,. The cathode of the first Zener tube is connected to the positive end of the fan and one end of the first capacitor, the other end of the first capacitor and the negative of the fan Extremely grounded,
Wherein, when the PWM signal generated by the MCU is low level, the FET is turned off, and the power supply voltage connected to the power supply interface is output to the anode of the first Zener diode to control the conduction of the first Zener diode, and the power supply interface is connected. The power supply voltage supplies power to the fan through the first voltage regulator tube, causes the fan to rotate, and simultaneously charges the first capacitor, and increases the operating voltage of the fan as the charging time of the first capacitor increases, thereby controlling the speed of the fan. . The fan drive circuit of claim 1, wherein when the PWM signal is at a high level, the FET is turned on, so that the anode of the first Zener diode is grounded through the conductive FET, the first stable The pressure tube is turned off accordingly, and the power supply to the fan is stopped, so that the fan stops rotating. The fan drive circuit of claim 2, wherein the fan drive circuit further includes a diode and a second voltage regulator, and an anode of the diode is connected to the cathode of the first voltage regulator The cathode is connected to the cathode of the second voltage regulator tube, the anode of the second voltage regulator tube is grounded, and the diode and the second voltage regulator tube have a bidirectional cut-off function, so that the first capacitor supplies power to the fan when the PWM signal is low level. The voltage output from the first capacitor is regulated. The fan drive circuit of claim 2, wherein the fan drive circuit further includes a second capacitor, one end is connected to the voltage 埠, and the other end is grounded, and the voltage and current for connecting the voltage 埠 are performed. Filtering. The fan drive circuit of claim 1, wherein the fan is of the type CN703. An electronic device includes a power source, a fan driving circuit and a fan. The fan driving circuit is configured to control a rotation and a rotation speed of a fan, and includes a micro control unit MCU and a power supply interface. The MCU is used to generate a fixed occupation. a PWM signal with an air ratio, the power interface is used to access the power supply voltage, and the improvement is that
The fan driving circuit further includes a first resistor, a field effect transistor, a first Zener diode, and a first capacitor. The gate of the FET is connected to the MCU, and is also grounded through the first resistor, the source of the FET. The pole is grounded, the drain is connected to the anode of the first Zener tube and is connected to the voltage ,. The cathode of the first Zener tube is connected to the positive end of the fan and one end of the first capacitor, the other end of the first capacitor and the negative of the fan Extremely grounded,
Wherein, when the PWM signal generated by the MCU is low level, the FET is turned off, and the power supply voltage connected to the power supply interface is output to the anode of the first Zener diode to control the conduction of the first Zener diode, and the power supply interface is connected. The power supply voltage supplies power to the fan through the first voltage regulator tube, causes the fan to rotate, and simultaneously charges the first capacitor, and increases the operating voltage of the fan as the charging time of the first capacitor increases, thereby controlling the speed of the fan. . The electronic device of claim 6, wherein when the PWM signal is at a high level, the FET is turned on, so that the anode of the first Zener diode is grounded through the conductive FET, the first voltage regulator The tube is cut off accordingly, and the power supply to the fan is stopped, so that the fan stops rotating. The electronic device of claim 7, wherein the fan driving circuit further includes a diode and a second voltage regulator, and an anode of the diode is connected to a cathode of the first voltage regulator. The cathode is connected to the cathode of the second voltage regulator tube, the anode of the second voltage regulator tube is grounded, and the diode and the second voltage regulator tube have a bidirectional cut-off function, so that the first capacitor supplies power to the fan when the PWM signal is low level. The voltage of the first capacitor output is regulated. The electronic device of claim 7, wherein the fan driving circuit further comprises a second capacitor, one end is connected to the voltage 埠, and the other end is grounded, and is used for filtering the voltage and current of the voltage 埠. . The electronic device of claim 6, wherein the fan is of the type CN703.