Philips Semiconductors

Product data

P82CF201

Low power, low price dual fan manager

2002 Nov 18

5

Motor Failure Detection and fault Reporting

(including watchdog reset)

of NPN transistor through an inverting buffer transistor (2N3904 or

PMBT3904D) which amplifies the signal from the low-value current

sensing resistor in the ground return leg of the fan circuit. During

normal fan operation, communication occurs as each pole of the fan

is energized.

voltage follower of the PWM pin.

resulting in a voltage drop. The commutation will cause a narrow

window where there is no current flow. Motor detection is done by

the presence of commutation pulses. If there is constant voltage

the motor is jammed. When there is no voltage at all, the motor

might not be connected or the MOSFET is defective. The fault

condition also triggers the maximum PWM applied to the running

fan.

the transistor is approx. 0.5 V. Table 1 lists some recommended

Figure 4

Nominal Fan Current(mA)

100

5.1

200

2.5

450

2.2

800

1.0

In addition, when the thermistor resistance falls below 1.7 K

Ω (for

NTC thermistor) indicating temperature above 76

°C, the fault line

will be asserted.

When the fan fails continuously, the fault signal will be held on LOW.

su01720

FANXDRIVE

3.3 V

12 V FAN

+12 V

Q1

SI4410DY

(2.2

Ω TYPICAL)

+12 V

3.3 V

Figure 4. Interfacing the 82CF201 to a 2-Wire fan.