CONTROL CIRCUIT FOR FAN

• US 20140097781A1
• Filed: 05/09/2013
• Published: 04/10/2014
• Est. Priority Date: 10/10/2012
• Status: Abandoned Application

• Current Assignee: Hong Fu Jin Precision Industry (Shenzhen) Co., Ltd. (Hon Hai Precision Industry Co., Ltd.), Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hong Fu Jin Precision Industry (Shenzhen) Co., Ltd. (Hon Hai Precision Industry Co., Ltd.), Hon Hai Precision Industry Co., Ltd.
• Inventors: WU, KANG, TIAN, BO
• Application Number:
  US13/891,177
• Publication Number:
  US 20140097781A1
• Time in Patent Office: Days
• US Class Current: 318/471
• CPC Class Codes: G05D 23/1931 to control the temperature of one space
• CPC Class Codes: G05D 23/20 with sensing elements having variation of electric or magnetic properties with change of temperature G05D23/13 takes precedence
• CPC Class Codes: G05D 23/24 the sensing element having a resistance varying with temperature, e.g. a thermistor
• CPC Class Codes: G06F 1/206 comprising thermal management
• CPC Class Codes: G06F 1/3206 Monitoring of events, devices or parameters that trigger a change in power modality
• CPC Class Codes: G06F 1/3234 Power saving characterised by the action undertaken
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A control circuit includes a temperature measuring module and a control module. The temperature measuring module includes a thermistor. The thermistor is arranged adjacent to an electronic element. The control module includes a monitoring chip and a register. The register stores a number of temperature values and duty cycle of a number of pulse width modulation (PWM) signals corresponding to the temperature values. The monitoring chip obtains temperature of the electronic element measured by the thermistor and outputs a PWM signal according to the measured temperature, to control a rotation speed of the fan.

Claims

1. A control circuit applicable to control a fan, the control circuit comprising:

a temperature measuring module comprising at least one thermistor, wherein the at least one thermistor is arranged adjacent to an electronic element; and

a control module connected to the temperature measuring module, and comprising a monitoring chip and a register, wherein the register stores a plurality of temperature values and duty cycle of a plurality of pulse width modulation (PWM) signals corresponding to the temperature values, the monitoring chip obtains temperature of the electronic element measured by the at least one thermistor, and outputs a PWM signal according to the measured temperature, to control a rotation speed of the fan.

2. The control circuit of claim 1, wherein the at least one thermistor comprises first to third thermistors.

3. The control circuit of claim 2, wherein first to third voltage sensing pins of the monitoring chip are grounded through the first to third thermistors, respectively, the first to third voltage sensing pins of the monitoring chip are also connected to a first end of a first capacitor through first to third resistors, respectively, a second end of the first capacitor is grounded, fourth and fifth voltage sensing pins of the monitoring chip are grounded, a first ground pin of the monitoring chip is connected to the first end of the first capacitor, a second ground pin of the monitoring chip is grounded, a first voltage pin of the monitoring chip is connected to a first power source and also grounded through a second capacitor, a third capacitor is connected to the second capacitor in parallel, a second voltage pin of the monitoring chip is connected to a second power source and also grounded through a fourth capacitor, a fifth capacitor is connected to the fourth capacitor in parallel, a sixth voltage sensing pin of the monitoring chip is connected to a third power source and also grounded through a sixth capacitor.

4. The control circuit of claim 3, wherein a clock pin of the monitoring chip is connected to an output pin of a clock chip through a fourth resistor, a ground pin of the clock chip is grounded, a voltage pin of the clock chip is connected to the second power source and also grounded through a seventh capacitor, an enable pin of the clock pin is connected to the second power source through a fifth resistor, an alarm pin of the monitoring chip is connected to the second power source through a sixth resistor.

5. The control circuit of claim 4, wherein a pulse signal pin of the monitoring chip is connected to a base of a first transistor through a seventh resistor, an emitter of the first transistor is grounded, a collector of the first transistor is connected to the first power source through an eighth resistor and also connected to a base of a second transistor, an emitter of the second transistor is grounded, a collector of the second transistor is connected to the first power source through a ninth resistor, the collector of the second transistor is also connected to a control pin of the fan connector, a fan pin of the monitoring chip is connected to a rotation speed pin of the fan connector through tenth and eleventh resistors in sequence, the rotation pin of the fan connector is also connected to a fourth power source through a twelfth resistor, a cathode of a diode is connected to the fourth power source, an anode of the diode is connected to the rotation speed pin of the fan connector, a voltage pin of the fan connector is connected to the fourth power source and also grounded through an eighth capacitor, a ground pin of the fan connector is grounded.

6. The control circuit of claim 5, wherein an address pin of the monitoring chip is connected to the second power source through a thirteenth resistor and also grounded through a fourteenth resistor, a data pin of the monitoring chip is connected to a serial data pin of the register and also connected to the second power source through a fifteenth resistor, first to third data pin of the register are connected together and then grounded through a sixteenth resistor, a ground pin of the register is grounded, a voltage pin of the register is connected to the second power source and also grounded through a ninth capacitor, a control pin of the register is grounded through a seventeenth resistor, a serial clock pin of the register is connected to a clock pin of the monitoring chip, the clock pin of the monitoring chip is also connected to the second power source through an eighteenth resistor.