TWI466625B - Fan delay controlling system - Google Patents

Description

Fan delay control system

The invention relates to a fan delay control system.

Some electronic devices, such as a computer system, typically have a fan inside to dissipate the electronic device. However, after the system power is turned off, the internal fan stops rotating due to the loss of power supply. At this time, the residual heat inside the computer system can only be released by passive heat dissipation. In the case of high ambient temperature, the internal temperature of the system will remain high for a period of time after shutdown, thereby shortening the service life of the computer system.

In view of the above, it is necessary to provide a fan delay control system that allows the fan to continue to rotate for a period of time after the system power is turned off.

A fan delay control system for controlling a fan in an electronic device, the fan delay control system comprising: a fan connector connected to the fan; a power supply module comprising first to fourth ends, the first The terminal is connected to a fan power supply, the second end is connected to a monitoring power supply, and the third end is connected to the fan connector. When the system power of the electronic device is not powered off, the power supply module sends the fan through the fan power supply. Power supply, when the system power of the electronic device is powered off, the power supply The module boosts the voltage of the monitoring power supply to supply power to the fan; and a power control module connected to the fourth end of the power supply module, the power control module is configured to sense the electronic device The temperature and correspondingly controls the power supply module. When the temperature in the electronic device is lower than a predetermined value, the power control module controls the power supply module to stop supplying power to the fan connector.

The fan delay control system of the present invention connects the first end of the power supply module to a fan power supply, the second end is connected to a monitoring power supply on the motherboard, and the third end is connected to the power end of the fan connector. The fourth end is connected to the power control module. The power supply module boosts the voltage of the monitoring power supply and then supplies power to the fan connector. When the temperature is lower than a predetermined value, the power control module controls the power supply module to stop supplying power to the fan connector. Therefore, the fan can continue to rotate for a period of time after the system power is cut off.

100‧‧‧fan

200‧‧‧Fan Connector

300‧‧‧Power supply module

400‧‧‧Power Control Module

500‧‧‧Speed Control Module

600‧‧‧Speed detection module

P1, VCC‧‧‧ power terminal

P2‧‧‧ control terminal

P3‧‧‧ Sense end

P4, GND‧‧‧ grounding terminal

S1‧‧‧ first end

S2‧‧‧ second end

S3‧‧‧ third end

S4‧‧‧ fourth end

V-c1‧‧‧fan power supply

V-s1‧‧‧Monitor power supply

Q1‧‧‧P type field effect transistor

Q2‧‧‧N type field effect transistor

U1‧‧‧PWM controller

FREQ‧‧‧ frequency input

SY/SH‧‧‧Shutdown/synchronous input

CS+‧‧‧ current sensing positive phase input

PGND‧‧‧gate drive/current sense inverting input

FB‧‧‧ feedback input

LDO‧‧‧5V chip regulator output

REF‧‧‧1.25V reference voltage output

EXT‧‧‧ gate drive output

L1‧‧‧Inductance

D1‧‧‧First Rectifier Diode

D2‧‧‧Secondary rectifier diode

D3‧‧‧ third rectifier diode

C1~C9‧‧‧ capacitor

R1‧‧‧ current sensor resistance

R2~R12‧‧‧ resistor

A, B, C‧‧‧ nodes

U2‧‧‧ comparator

IN1+‧‧‧ first positive input

IN1-‧‧‧ first negative input

OUT1‧‧‧ first output

IN2+‧‧‧second positive input

IN2-‧‧‧ second negative input

OUT2‧‧‧ second output

RT‧‧‧Thermistor

U3‧‧‧ buffer

V-c2, V-s2‧‧‧ power supply

I‧‧‧ input

Y‧‧‧ output

DW‧‧‧ Regulators

1 is a block diagram of a preferred embodiment of a fan delay control system of the present invention.

2 is a circuit diagram of the power supply module of FIG.

3 is a circuit diagram of the power control module of FIG. 1.

4 is a circuit diagram of the speed control module of FIG. 1.

Referring to FIG. 1, the fan delay control system of the present invention is used to control a fan 100 in an electronic device to continue to rotate for a period of time after the system power supply of the electronic device is powered off to discharge residual heat inside the electronic device. The preferred embodiment of the fan delay control system includes a fan connector 200, a power supply module 300, a power control module 400, a speed control module: 00, and a speed detecting module 600. This implementation In the mode, the electronic device is a computer system.

The fan connector 200 is connected to the fan 100. The fan connector 200 includes a power terminal P1, a control terminal P2, a sensing terminal P3, and a ground terminal P4. The power terminal P1 of the fan connector 200 is used to supply power to the fan 100. The control terminal P2 is used to control the rotation speed of the fan 100. The sensing terminal P3 is used to sense the rotation speed of the fan 100, and the ground terminal P4 is grounded.

The first end S1 of the power supply module 300 is connected to a fan power supply V-c1, the second end S2 is connected to a monitoring power supply V-s1 located on a motherboard of the computer system, and the third end S3 is connected to the fan. The power terminal P1 of the battery 200 is connected to supply the power of the fan power source V-c1 to the fan connector 200. In this embodiment, the fan power supply V-c1 is a +12V power supply provided by the motherboard in the computer system, and the monitoring power supply V-s1 is a +5V_SB power supply provided by the motherboard in the computer system.

The power control module 400 is connected to the fourth end S4 of the power supply module 300 for sensing the temperature inside the computer system and controlling the power supply module 300. When the temperature inside the computer system is lower than a predetermined value, the power control module 400 controls the power supply module 300 to stop supplying power to the fan connector 200.

The speed control module 500 is connected to the control terminal P2 of the fan connector 200 to transmit a corresponding control signal to the fan connector 200, thereby controlling the rotation speed of the fan 100.

The rotation speed detecting module 600 is connected to the sensing end P3 of the fan connector 200 to sense the rotation speed of the fan 100.

The working process of the fan delay control system of the present invention will be described below.

When the power of the computer system is not powered off, the fan power supply V-c1 is from the computer system The motherboard is provided. At this time, the power supply module 300 supplies power to the fan 100 through the fan power source V-c1.

When the power of the computer system is powered off, the motherboard of the computer system cannot provide the fan power supply V-c1, and the +5V_SB power supply provided by the motherboard is less than the working voltage of the fan 100 by 12V, so the power supply module is used at this time. 300 powers the fan 100 after raising the voltage of the monitoring power source V-s1 to 12V.

The power control module 400 senses the temperature within the computer system and converts the temperature into a voltage value. The power control module 400 is further configured to compare the voltage value and a preset voltage value, and correspondingly control the power supply module 300. When the voltage value is lower than the preset voltage value, it indicates that the temperature in the computer system is lower than a predetermined value, indicating that the residual heat in the computer system has been discharged at this time, and the power control module 400 controls the power supply mode. Group 300 stops powering the fan connector 200, thereby turning off the fan 100 to conserve power. When the voltage value is not less than the preset voltage value, that is, the temperature in the computer system is higher than a predetermined value, the power control module 400 controls the power supply module 300 to continue to supply power to the fan connector 200.

Referring to FIG. 2 together, the power supply module 300 includes a P-type field effect transistor Q1, an N-type field effect transistor Q2, a PWM controller U1, an inductor L1, and a first rectifying diode D1. a second rectifying diode D2, a third rectifying diode D3, a current sensor resistor R1, resistors R2 R4 and capacitors C1~C7.

The anode of the third rectifying diode D3 is connected to the fan power source V-c1, that is, the +12V power supply on the motherboard, as the first end S1 of the power supply module 300. The cathode of the second rectifying diode D2 is connected to the cathode of the third rectifying diode D3 and is connected to the power terminal P1 of the fan connector 200 as the third end S3 of the power supply module 300. The source of the P-type field effect transistor Q1 serves as the second end S2 of the power supply module 300 The monitoring power supply V-s1, that is, the +5V_SB power supply on the motherboard.

The gate of the P-type field effect transistor Q1 is connected to the fan power source V-c1. The drain of the P-type field effect transistor Q1 is grounded through the capacitor C1 and is also connected to one end of the inductor L1. This capacitor C1 is used to reduce noise interference. The node between the drain of the P-type field effect transistor Q1 and the capacitor C1 is denoted by A.

The drain of the N-type field effect transistor Q2 is connected to the other end of the inductor L1 and the anode of the first rectifying diode D1. The source of the N-type field effect transistor Q2 is grounded through the current sensor resistor R1. The cathodes of the first rectifying diode D1 are grounded through the three capacitors C2, C3, and C4, respectively, and are also connected to the anode of the second rectifying diode D2.

The PWM controller U1 uses a MAX668 PWM controller manufactured by Maxim, which includes a power supply terminal VCC, a ground terminal GND, a frequency input terminal FREQ, a shutdown/synchronization input terminal SY/SH, and a Current sense positive phase input terminal CS+, one gate drive/current sense inverting input terminal PGND, one feedback input terminal FB, a 5V chip regulator output terminal LDO, a 1.25V reference voltage output terminal REF and a gate drive Output EXT.

The power supply terminal VCC of the PWM controller U1 is connected to the 5V chip voltage regulator output terminal LDO and is also connected to the drain of the P-type field effect transistor Q1. The 5V chip regulator output terminal LDO is also grounded through the capacitor C5.

The shutdown/synchronization input terminal SY/SH is connected to the power control module 400 as the fourth terminal S4 of the power supply module 300. When the stop/synchronization input terminal SY/SH receives a low level, the PWM controller U1 stops working; when the stop/synchronization input terminal SY/SH receives a high level, the PWM controller U1 is set with the frequency input terminal FREQ. The frequency outputs a square wave signal.

The 1.25V reference voltage output terminal REF is grounded through the capacitor C6. The frequency input terminal FREQ is grounded through the resistor R2. The gate drive output EXT is coupled to the gate of the N-type field effect transistor Q2. The current sensing non-inverting input terminal CS+ is connected to the source of the N-type field effect transistor Q2 and is connected to the gate driving/current sensing inverting input terminal PGND through the current sensor resistor R1. The gate drive/current sense inverting input PGND is grounded. The feedback input terminal FB is connected to the cathode of the first rectifying diode D1 through the resistor R3, and is also grounded through the resistor R4. The feedback input terminal FB is also grounded through the capacitor C7. The ground terminal GND is grounded.

When the power of the computer system is not powered off, the source voltage of the P-type field effect transistor Q1 is +5V, and the gate voltage is +12V. According to the characteristics of the P-type field effect transistor Q1, it can be seen that the P-type field effect transistor Q1 is turned off at this time, and the PWM controller U1 does not operate. At this time, the cathode of the first rectifying diode D1 has no output, and the fan power source V-c1 supplies power to the fan 100 through the third rectifying diode D3 and the fan connector 200. This process works the same as the fan of an existing computer system.

When the power supply of the computer system is powered off, since the fan power supply V-c1 has no voltage, the source voltage of the P-type field effect transistor Q1 is +5V, and the gate voltage is 0V. At this time, the P-type field effect transistor Q1 is turned on. The PWM controller U1 is energized to start working.

The PWM controller U1 controls the N-type field effect transistor Q2 to be turned on or off through a square wave signal outputted by the gate drive output terminal EXT. When the gate drive output terminal EXT outputs a high level, the N-type field effect transistor Q2 is turned on, and the drain of the P-type field effect transistor Q1 charges the inductor L1; when the gate drive output terminal EXT output is low At the level, the N-type field effect transistor Q2 is turned off, and the drain of the P-type field effect transistor Q1 and the inductor L1 are simultaneously discharged. At this time, the cathode voltage of the first rectifying diode D1 will be higher than the P type. The drain voltage of the field effect transistor Q1. By changing the high and low levels of the square wave signal The duration of the level changes the charging and discharging time of the inductor L1 such that the cathode voltage of the first rectifying diode D1 rises, thereby converting +5 V SB to +12 V. The +12V voltage supplies power to the fan 100 through the second rectifying diode D2. The inductor L1, the N-type field effect transistor Q2, the first rectifying diode D1, and the capacitors C2, C3, and C4 form a booster circuit, and the working principle thereof is known in the art, and details are not described herein. .

Referring to FIG. 3 together, the power control module 400 includes a comparator U2, a thermistor RT having a negative temperature coefficient, a capacitor C8, resistors R5 R7 and R11, and R12.

One end of the resistor R5 is connected to the node A between the drain of the P-type field effect transistor Q1 and the capacitor C1, and the other end is grounded through the resistor R7. One end of the resistor R6 is connected to the drain of the P-type field effect transistor Q1, and the other end is grounded through the thermistor RT. The capacitor C8 is connected in parallel with the thermistor RT. The node between the resistor R6 and the thermistor RT is denoted by B, and the node between the resistors R5 and R7 is denoted by C. The capacitor C8 is used to prevent the voltage of the node B from fluctuating frequently to reduce interference.

The comparator U2 uses a dual comparator model LM393 manufactured by Motorola. The LM393 comparator includes a first positive input terminal IN1+, a first negative input terminal IN1, a first output terminal OUT1, a second positive input terminal IN2+, a second negative input terminal IN2-, and a second output. The terminal OUT2, a power terminal VCC and a ground terminal GND. The first positive input terminal IN1+ of the LM393 comparator is connected to the node C between the resistors R5 and R7, and the first negative input terminal IN1 is connected to the node B between the resistor R6 and the thermistor RT, the first output. The terminal OUT1 is connected to the fourth end S4 of the power supply module 300 and is connected to the drain of the P-type field effect transistor Q1 through the resistor R11. The power terminal VCC is connected to the monitoring power source V-s1, and the ground terminal GND is grounded. . The second positive input terminal IN2+ of the LM393 comparator is grounded, and the second negative input terminal IN2- is connected to the second output terminal OUT2.

The resistor R12 is connected between the first positive input terminal IN1+ of the comparator U2 and the first output terminal OUT1. The resistor R12 and the comparator U2 form a hysteresis comparator to prevent interference.

After the computer system is powered off, when the temperature in the computer system drops, the resistance of the thermistor RT increases, causing the voltage of the node B between the resistor R6 and the thermistor RT to rise. When the temperature in the computer system drops to a preset value, it means that the residual heat inside the computer system has been discharged. At this time, the voltage of the node B is higher than the voltage of the node C between the resistors R5 and R7. That is, the voltage of the first negative input terminal IN1- of the comparator U2 is higher than the voltage of the first positive input terminal IN1+, and the first output terminal OUT1 of the comparator U2 outputs a low level, thereby making the PWM controller U1 The shutdown/synchronization input terminal SY/SH is at a low level, and the PWM controller U1 stops working, so that the power supply module 300 stops supplying power to the fan connector 200, thereby turning off the fan 100.

Referring to FIG. 4 together, the speed control module 500 includes a buffer U3 and two resistors R8 and R9. The power terminal VCC of the buffer U3 is connected to a power source V-c2, and the ground terminal GND is grounded. The input terminal I of the buffer U3 is connected to the power source V-c2 through the resistor R8, and the input terminal I of the buffer U3 receives a pulse width modulation signal PWM. The output terminal Y of the buffer U3 is connected to a power source V-s2 through the resistor R9, and the output terminal Y of the buffer U3 is connected to the control terminal P2 of the fan connector 200. The power supply V-c2 is a +3.3V power supply on the motherboard, and the power supply V-s2 is a +3.3V_SB power supply on the motherboard. Wherein, the pulse width modulation signal PWM is derived from an I/O control chip on the motherboard, and the I/O control chip outputs a pulse width modulation signal PWM corresponding to a duty cycle according to a temperature in the computer system, thereby correspondingly controlling The rotational speed of the fan 100.

The buffer U3 uses a 74LVC07A buffer manufactured by Philips Semiconductors. The relationship between the input terminal I and the output terminal Y of the 74LVC07A buffer is as shown in Table 1:

Where "L" indicates a low level, "H" indicates a high level, and "Z" indicates a high resistance state. When the buffer operates and its input terminal I inputs a low level, its output terminal Y outputs a low level; when the buffer operates and the input terminal I inputs a high level, its output terminal Y is in a high impedance state, which is equivalent to disconnection. .

When the power of the computer system is not powered off, the speed control module 500 controls the speed of the fan 100 through the power source V-c2, the pulse width modulation signal PWM, the buffer U3, and the power source V-s2. The I/O control chip outputs a pulse width modulation signal PWM having a corresponding duty cycle according to the temperature, so that the rotation speed of the control fan 100 is known in the PC field, and will not be described herein.

When the computer system power is cut off, the power supply V-c2 cannot be provided by the motherboard in the computer system, and the buffer U3 does not work. At this time, the control terminal P2 of the fan connector 200 receives the power source V-s2, thereby controlling the fan 100 to operate at full speed.

The power terminal P1 of the fan connector 200 is connected to the cathode of a voltage stabilizing diode DW, and the anode of the voltage stabilizing diode DW is grounded. The power terminal P1 of the fan connector 200 is also grounded through a capacitor C9 and connected to the sensing terminal P3 of the fan connector 200 through a resistor R10. The Zener diode DW is used to stabilize the power of the power terminal P1 of the fan connector 200. The capacitor C9 and the resistor R10 are used for overvoltage protection of the power terminal P1 of the fan connector 200.

The fan delay control system of the present invention connects the power supply module 300 to the +5V_SB on the motherboard, so that when the computer system is powered off, the +5V power supply can be raised to +12V through the power supply module 300, thereby The fan connector 200 is powered, and when the temperature inside the computer system is lower than a predetermined value, the power supply module 300 is controlled by the power control module 400 to stop supplying power to the fan connector 200. The fan delay control system can cause the fan 100 to continue to rotate for a period of time after the system power is turned off to discharge residual heat inside the computer system.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. However, the above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be covered by the following claims.

100‧‧‧fan

200‧‧‧Fan Connector

300‧‧‧Power supply module

400‧‧‧Power Control Module

500‧‧‧Speed Control Module

600‧‧‧Speed detection module

P1‧‧‧ power terminal

P2‧‧‧ control terminal

P3‧‧‧ Sense end

P4‧‧‧ Grounding terminal

S1‧‧‧ first end

S2‧‧‧ second end

S3‧‧‧ third end

S4‧‧‧ fourth end

V-c1‧‧‧fan power supply

V-s1‧‧‧Monitor power supply

Claims (8)

A fan delay control system for controlling a fan in an electronic device, the fan delay control system comprising: a fan connector connected to the fan; a power supply module comprising: a P-type field effect transistor; The source is connected to the monitoring power source, and the gate is connected to the fan power source; an inductor has one end connected to the drain of the P-type field effect transistor; a capacitor; a first rectifying diode, the cathode of which is passed through the cathode a capacitor is grounded; a second rectifying diode having an anode connected to the cathode of the first rectifying diode and a cathode connected to the fan connector; a third rectifying diode having an anode connected to the fan power source and a cathode Connected to the fan connector; an N-type field effect transistor having a drain connected to the other end of the inductor and an anode of the first rectifying diode, the source being grounded through a current sensor resistor; and a PWM The controller includes a power terminal, a ground terminal, a frequency input terminal, a stop/synchronization input terminal, a current sensing positive phase input terminal, a gate drive/current sensing inversion input terminal, and a feedback input terminal. 5V chip regulator output, a 1.25V reference voltage output and a gate drive output, the 5V chip regulator output is grounded through a capacitor, the PWM controller's power supply and 5V chip regulator output And the P-type field effect transistor has a drain connected to each other, the gate drive output end is connected to the gate of the N-type field effect transistor, and the current sense positive phase input terminal is connected to the source of the N-type field effect transistor. And through the current sensor resistance and the gate drive / current sense The inverting input terminal is connected, and the feedback input terminal is connected to the cathode of the first rectifying diode through a resistor and grounded through a resistor. The 1.25V reference voltage output terminal is grounded through a capacitor, and the frequency input end is grounded through a resistor. The ground terminal and the gate driving/current sensing inverting input end are grounded; when the system power of the electronic device is not powered off, the power supply module supplies power to the fan through the fan power source, when the electronic device system When the power is cut off, the power supply module boosts the voltage of the monitoring power supply to supply the fan; and a power control module connected to the shutdown/synchronization input end of the PWM controller, the power control module The method is configured to sense a temperature in the electronic device and correspondingly control the power supply module. When the temperature in the electronic device is lower than a predetermined value, the power control module controls the power supply module to stop supplying power to the fan connector. . The fan delay control system of claim 1, wherein the electronic device is a computer system, and the fan power supply is a +12V power supply provided by a motherboard of the computer system, and the monitoring power supply is a host in the computer system. The +5V_SB power supply provided by the board. The fan delay control system of claim 1, wherein the power control module comprises: a first resistor; a second resistor, one end of which is connected to the drain of the P-type field effect transistor, and the other end Grounded through the first resistor; a thermistor; a third resistor having one end connected to the drain of the P-type field effect transistor and the other end grounded through the thermistor; and a comparator having a positive input terminal Connected to the node between the first resistor and the second resistor, the negative input terminal is connected to the node between the third resistor and the thermistor, and the output terminal is connected to the stop/synchronization input end of the PWM controller, and the power terminal Connected to the monitoring power supply, the ground terminal is grounded. The fan delay control system of claim 1, wherein the fan connector comprises a power end and a ground end, the ground end of the fan connector is grounded, and the power end is connected to a voltage stabilizing diode The cathode is connected and the anode of the voltage stabilizing diode is grounded. The fan delay control system of claim 4, wherein the fan connector further comprises a sensing end, the power end of the fan connector is also grounded through a capacitor and transmitted through a resistor and the fan connector. The measuring ends are connected. The fan delay control system of claim 5, further comprising a rotation speed detecting module connected to the sensing end of the fan connector to sense the rotation speed of the fan. The fan delay control system of claim 4, further comprising a speed control module, the fan connector further comprising a control end, the speed control module being connected to the control end of the fan connector for controlling The speed of the fan. The fan delay control system of claim 7, wherein the speed control module comprises: a first resistor; a second resistor; and a buffer, the power end of which is connected to a first power source, the ground end The grounding end is connected to the first power source through the first resistor and receives a pulse width modulation signal. The output end is connected to a second power source through the second resistor and is connected to the control end of the fan connector.