FAN CONTROLLING CIRCUIT

• US 20100014843A1
• Filed: 09/30/2008
• Published: 01/21/2010
• Est. Priority Date: 07/18/2008
• Status: Active Grant

• 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: Peng, Zhi-Jian, Yeh, Chin-Wen, Sun, Hai-Shan
• Granted Patent: US 8,076,879 B2
• Time in Patent Office: Days
• US Class Current: 388/800
• CPC Class Codes: F04D 27/004 by varying driving speed
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A fan controlling circuit for detecting rotational speed of a fan, includes a comparison circuit and a controlling chipset. The comparison circuit receives a rotational speed signal from the fan at one input terminal, a reference voltage at another input terminal, and outputs a filtered rotational speed signal at an output terminal. The controlling chipset receives the filtered rotational speed signal, and outputs control signals to control the rotational speed of the fan.

Claims

1. A fan controlling circuit for detecting a rotational speed of a fan, comprising:

a comparison circuit configured for receiving a rotational speed signal from the fan at one input terminal, a reference voltage at another input terminal, and outputting a filtered rotational speed signal at an output terminal; and

a controlling chipset for receiving the filtered rotational speed signal, and outputting a control signal to control the rotational speed of the fan.

2. The fan controlling circuit of claim 1, wherein the comparison circuit comprises a comparator, a first resistor, and a second resistor;

the inverting input terminal of the comparator is configured to receive the rotational speed signal;

the non-inverting input terminal of the comparator is configured to receive the reference voltage via the first resistor;

the output terminal of the comparator is coupled to the controlling chipset, and is coupled to the non-inverting input terminal of the comparator via the second resistor.

3. The fan controlling circuit of claim 2, wherein the comparison circuit has a threshold voltage width greater than amplitudes of noise signals.

4. The fan controlling circuit of claim 3, wherein the comparison circuit further comprises a third resistor and a fourth resistor;

the inverting input terminal of the comparator is configured to receive the rotational speed signal via the third resistor;

the output terminal of the comparator is coupled to the controlling chipset and the second resistor via the fourth resistor.

5. The fan controlling circuit of claim 4, wherein the comparison circuit further comprises a zener diode, a node between the second and fourth resistors is grounded via the zener diode.

6. The fan controlling circuit of claim 5, wherein the zener diode is a dual zener diode.

7. The fan controlling circuit of claim 6, further comprising a super input/output controller configured for receiving the control signals, and outputting a pulse width modulation signal to control the rotational speed of the fan.

8. The fan controlling circuit of claim 7, wherein the controlling chipset is a basic input output system chipset.