CN102444603A

CN102444603A - Fan control circuit

Info

Publication number: CN102444603A
Application number: CN2010105057582A
Authority: CN
Inventors: 谢明志
Original assignee: Hongfujin Precision Industry Shenzhen Co Ltd; Hon Hai Precision Industry Co Ltd
Current assignee: Hongfujin Precision Industry Shenzhen Co Ltd; Hon Hai Precision Industry Co Ltd
Priority date: 2010-10-13
Filing date: 2010-10-13
Publication date: 2012-05-09

Abstract

A fan control circuit includes a triangular wave generating circuit, a temperature induction circuit, comparator and a switching circuit, wherein the triangular wave generating circuit is connected with a forward direction input end of the comparator and used for outputting a triangle waveform signal to the comparator; the temperature induction circuit is connected with a reversed direction input end of the comparator and used for detecting the environmental temperature and outputting a corresponding temperature signal to the comparator; the comparator is used for comparing the intensity of the triangle waveform signal and the temperature signal, and correspondingly outputting a control signal to the switching circuit, so as to control the on/off of the switching circuit; and the switching circuit is connected between a power supply and a fan. The fan control circuit can be used for reducing load of a central processor.

Description

Fan control circuitry

Technical field

The present invention relates to a kind of fan control circuitry.

Background technique

The radiation system of inside computer system generally all is to send the rotating speed that corresponding pulse width modulating signal is adjusted fan through central processing unit (CPU) according to the temperature in the cabinet at present.But this mode can increase the load of central processing unit (CPU).

Summary of the invention

In view of above content, be necessary to provide a kind of fan control circuitry that does not utilize central processing unit (CPU), it can reduce the load of central processing unit (CPU).

A kind of fan control circuitry; Comprise a circuit for generating triangular wave, a temperature sense circuit, one first comparator and a switching circuit; This circuit for generating triangular wave links to each other with the positive input of this first comparator; Be used to export a triangular signal to this first comparator; This temperature sense circuit links to each other with the reverse input end of this first comparator, is used for sense ambient temperature and exports a corresponding temperature signal to this first comparator, and this first comparator is the size of this triangular signal and temperature signal relatively; And corresponding output one controls signal to this switching circuit to control the closed of this switching circuit or to break off, and this switching circuit is connected between a power supply and the fan.

The said fans control circuit can be under the situation of not utilizing central processing unit (CPU) according to the rotating speed of the temperature controlled fan of cabinet, thereby can reduce the load of central processing unit (CPU).

Description of drawings

Fig. 1 is the skeleton diagram of the preferred embodiments of fan control circuitry of the present invention.

Fig. 2 is the circuit diagram of first preferred embodiments of Fig. 1 fan control circuit.

First schematic representation of the control signal that triangular signal that Fig. 3 is produced for Fig. 2 intermediate cam wave generation circuit and comparator are exported.

Second schematic representation of the control signal that triangular signal that Fig. 4 is produced for Fig. 2 intermediate cam wave generation circuit and comparator are exported.

Fig. 5 is the circuit diagram of second preferred embodiments of Fig. 1 fan control circuit.

The primary component symbol description

Circuit for generating triangular wave 10,10 '

Temperature sense circuit 12,12 '

Comparator 11, U1, U1 ', U2, U2 ', U3, U3 '

Switching circuit 15,15 '

Fan 20

Power supply 30, Vcc

Resistance R 1, R1 ', R2, R2 ', R3, R3 ', R4, R4 ', R5,

R5’、R6、R6’、R7、R7’、R8、R9、R10

Capacitor C 1, C1 ', C2, C2 '

Triode Q1, Q1 ', Q2, Q2 ', Q3, Q3 '

Embodiment

Below in conjunction with accompanying drawing and preferred embodiments the present invention is described in further detail:

See also Fig. 1, the preferred embodiments of fan control circuitry of the present invention comprises a circuit for generating triangular wave 10, a temperature sense circuit 12, a comparator 11, a switching circuit 15 and a power supply 30.

This circuit for generating triangular wave 10 links to each other with the positive input of this comparator 11, is used to export a triangular signal to this comparator 11.

This temperature sense circuit 12 links to each other with the reverse input end of this comparator 11, is used for sense ambient temperature and exports a corresponding temperature signal to this comparator 11.This comparator 11 is the size of this triangular signal and temperature signal relatively, and corresponding output one controls signal to this switching circuit 15.

This switching circuit 15 is connected between this power supply 30 and the fan 20, and closed or break off being connected between this power supply 30 and the fan 20 according to this control signal, thus the corresponding working state of controlling this fan 20.

See also Fig. 2, in first preferred embodiments of this fan control circuitry, this circuit for generating triangular wave 10 comprises two comparator U2, U3 and a NPN triode Q1.The positive input ground connection of this comparator U2; Reverse input end links to each other with the output terminal of this comparator U2 through a capacitor C 1, also links to each other with the output terminal of this comparator U3 through a resistance R 1, and the power end of this comparator U2 links to each other with power Vcc (being power supply 30 in the preceding text); Grounding end ground connection; Output terminal links to each other with the positive input of this comparator U3 through a resistance R 2, and the positive input of this comparator U3 also links to each other the reverse input end ground connection of this comparator U3 through resistance R 3 with its output terminal; Power end links to each other with this power Vcc, grounding end ground connection.The output terminal of this comparator U3 also links to each other with the base stage of resistance R 4 with NPN triode Q1 through capacitor C 2 successively, and the base stage of this NPN triode Q1 also links to each other with this power Vcc through resistance R 5, grounded-emitter connection, and collector electrode links to each other with power Vcc through resistance R 6.The collector electrode of this NPN triode Q1 also links to each other as the positive input of the output terminal of this circuit for generating triangular wave 10 and this comparator U1 (be among Fig. 1 11).

This temperature sense circuit 12 comprises a resistance R 7 and a positive temperature coefficient thermistor PTC; This power Vcc links to each other with the reverse input end of this comparator U1 through resistance R 7; The end ground connection of this positive temperature coefficient thermistor PTC, the other end are connected between the reverse input end and resistance R 7 of this comparator U1.The grounding end ground connection of this comparator U1, power end links to each other with power Vcc.

This switching circuit 15 comprises a PNP triode Q2, and the emitter of this PNP triode Q2 links to each other with power Vcc, and base stage links to each other with the output terminal of comparator U1 through resistance R 8, and collector electrode links to each other with this fan 20.

To the working principle of Fig. 2 fan control circuit be described below:

This circuit for generating triangular wave 10 produces fixing triangular signal, and shown in Tri among Fig. 3 and Fig. 4, this triangular signal is exported to this comparator U1.

Suppose that temperature in chassis is higher at this moment; Characteristic according to positive temperature coefficient thermistor PTC; This moment, the resistance of this positive temperature coefficient thermistor PTC was higher; Thereby it is higher to make that power Vcc exports the magnitude of voltage of comparator U1 (being " temperature signal " in the preceding text) to after dividing potential drop, shown in magnitude of voltage Va among Fig. 3.

According to the working principle of comparator U1, when the voltage of its positive input is higher than the voltage of its reverse input end, its output terminal output high level signal.On the contrary, when the voltage of its positive input is lower than the voltage of its reverse input end, its output terminal output low level signal.Therefore, the control signal of this comparator U1 output shown in PWM-OUT1 among Fig. 3, it has first dutycycle.

Suppose that temperature in chassis is lower at this moment; Characteristic according to positive temperature coefficient thermistor PTC; This moment, the resistance of this positive temperature coefficient thermistor PTC was lower; Thereby it is lower to make that power Vcc exports the magnitude of voltage of comparator U1 (being " temperature signal " in the preceding text) to after dividing potential drop, shown in Fig. 4 magnitude of voltage Vb.Therefore, the control signal of this comparator U1 output shown in PWM-OUT2 among Fig. 4, it has second dutycycle.Obviously, first dutycycle can know according to the dutycycle of control signal less than second dutycycle, and the rotating speed of this fan 20 will be higher than the rotating speed of temperature in chassis fan 20 when low when temperature in chassis is higher.

The said fans control circuit can make under the situation of not utilizing central processing unit (CPU) that the rotating speed rotating speed lower, fan 20 when temperature in chassis is higher of fan 20 is higher when temperature in chassis is low, thereby can reduce the load of central processing unit (CPU).

See also Fig. 5; Second preferred embodiments of this fan control circuitry and the difference of first preferred embodiments are that this temperature sense circuit 12 ' comprises resistance R 7 ' and negative tempperature coefficient thermistor NTC in second preferred embodiments; This switching circuit 15 ' comprises PNP triode Q2 ' and NPN triode Q3, and the output terminal of this comparator U1 ' links to each other the grounded-emitter connection of this NPN triode Q3 through resistance R 8 ' with the base stage of NPN triode Q3; Collector electrode links to each other with power Vcc through resistance R 9; Also link to each other with the base stage of PNP triode Q2 ' through resistance R 10, the emitter of this PNP triode Q2 ' links to each other with power Vcc, and collector electrode links to each other with this fan 20.

Identical with the principle of Fig. 2 fan control circuit; When temperature in chassis not simultaneously; This comparator U1 has output the control signal of different duty; Thereby control switch circuit 15 ' has corresponding working state, so that fan 20 can rotating speed be slow when temperature is low, rotating speed is very fast when temperature is higher.

Claims

1. fan control circuitry; Comprise a circuit for generating triangular wave, a temperature sense circuit, one first comparator and a switching circuit; This circuit for generating triangular wave links to each other with the positive input of this first comparator; Be used to export a triangular signal to this first comparator; This temperature sense circuit links to each other with the reverse input end of this first comparator, is used for sense ambient temperature and exports a corresponding temperature signal to this first comparator, and this first comparator is the size of this triangular signal and temperature signal relatively; And corresponding output one controls signal to this switching circuit to control the closed of this switching circuit or to break off, and this switching circuit is connected between a power supply and the fan.

2. fan control circuitry as claimed in claim 1; It is characterized in that: this temperature sense circuit comprises a divider resistance and a positive temperature coefficient thermistor; One end of this divider resistance links to each other with this power supply; The other end links to each other with the reverse input end of this first comparator, an end ground connection of this positive temperature coefficient thermistor, and the other end is connected between the reverse input end and divider resistance of this first comparator.

3. fan control circuitry as claimed in claim 2; It is characterized in that: this switching circuit comprises a PNP triode; The emitter of the one PNP triode links to each other with this power supply, and base stage links to each other with the output terminal of first comparator through one first resistance, and collector electrode links to each other with this fan.

4. fan control circuitry as claimed in claim 1; It is characterized in that: this temperature sense circuit comprises a divider resistance and a negative tempperature coefficient thermistor; One end of this divider resistance links to each other with this power supply; The other end links to each other with the reverse input end of this first comparator, an end ground connection of this negative tempperature coefficient thermistor, and the other end is connected between the reverse input end and divider resistance of this first comparator.

5. fan control circuitry as claimed in claim 4; It is characterized in that: this switching circuit comprises one the one PNP triode and one the one NPN triode; The output terminal of this first comparator links to each other with the base stage of a NPN triode through one first resistance; The grounded-emitter connection of the one NPN triode, collector electrode links to each other with this power supply through one second resistance, also links to each other with the base stage of a PNP triode through one the 3rd resistance; The emitter of the one PNP triode links to each other with this power supply, and collector electrode links to each other with this fan.

6. fan control circuitry as claimed in claim 1; It is characterized in that: this circuit for generating triangular wave comprises one second comparator, one the 3rd comparator and a NPN triode; The positive input ground connection of this second comparator; Reverse input end links to each other with its output terminal through one first electric capacity; Also link to each other with the output terminal of the 3rd comparator through one first resistance, the output terminal of this second comparator links to each other with the positive input of the 3rd comparator through one second resistance, and the positive input of the 3rd comparator also links to each other with its output terminal through one the 3rd resistance; The reverse input end ground connection of the 3rd comparator; The output terminal of the 3rd comparator also links to each other with the base stage of this NPN triode with one the 4th resistance through one second electric capacity successively, and the base stage of this NPN triode also links to each other grounded-emitter connection through one the 5th resistance with this power supply; Collector electrode links to each other with power supply through one the 6th resistance, and the collector electrode of this NPN triode also links to each other with the positive input of this first comparator as the output terminal of this circuit for generating triangular wave.