US Patent No. 9,883,611

FAN CONTROL CIRCUIT


Patent No. 9,883,611
Issue Date January 30, 2018
Title Fan Control Circuit
Inventorship Yu-Chia Chen, New Taipei (TW)
Assignee HON HAI PRECISION INDUSTRY CO., LTD., New Taipei (TW)

Claim of US Patent No. 9,883,611

1. A fan control circuit comprising:
a plurality of temperature detection units, each of the temperature detection units configured to detect an operation temperature
of each of a plurality of heat elements, respectively, and output a temperature detection signal corresponding to each of
the heat elements;

a temperature synthesizing unit coupled to the plurality of temperature detection units, the temperature synthesizing unit
configured to calculate and output mean temperature signals according to the plurality of temperature detection signals and
a plurality of predetermined weighted values corresponding to the heat elements;

a driving signal generation unit coupled to the temperature synthesizing unit, the driving signal generation unit configured
to generate driving signals to a fan, according to the mean temperature signals, the driving signal generation unit comprising
a triangular wave signal generation unit configured to generate triangular wave signals, and the triangular wave signal generation
unit comprising:

a first comparator comprising a positive input terminal, a negative input terminal, and an output terminal, the negative input
terminal grounded;

a first resistor with a first end coupled to the positive input terminal of the first comparator;
a second resistor with a first end coupled to the output terminal of the first comparator and a second end coupled to a node
between the first resistor and the first comparator;

a third resistor with a first end coupled to the output terminal of the first comparator;
a second comparator comprising a positive input terminal, a negative input terminal, and an output terminal, the positive
input terminal grounded, the negative input terminal coupled to a second end of the third resistor, and the output terminal
coupled to a second end of the first resistor; and

a capacitor coupled between the negative input terminal of the second comparator and the output terminal of the second comparator;
wherein, frequency of the triangular wave signals output by the triangular wave signal generation unit is calculated by formulas:
R5/(4*R4*R6*C1), and F represents the frequency of the triangular wave signals, and R4 represents resistances of the first resistor, R5 represents resistances of the second resistor, R6 represents resistances of the third resistor, and C1 represents capacitance of the first capacitor.