TC654(2002) View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

TC654
(Rev.:2002)

Dual SMBus™ PWM Fan Speed Controllers With Fan Fault Detection

Microchip Technology 

TC654/TC655

3.0 PIN FUNCTIONS

The descriptions of the pins are listed in Table 3-1.

TABLE 3-1: PIN FUNCTION TABLE

Name

VIN

CF

SCLK

SDA

GND

FAULT

SENSE2

SENSE1

VOUT

VDD

Function

Analog Input

Analog Output

Serial Clock Input

Serial Data In/Out (Open Drain)

Ground

Digital (Open Drain) Output

Analog Input

Analog Input

Digital Output

Power Supply Input

3.1 Analog Input (VIN)

A voltage range of 1.62 V to 2.6 V (typical) on this pin

drives an active duty-cycle of 30% to 100% on the

VOUT pin.

3.2 Analog Output (CF)

Positive terminal for the PWM ramp generator timing

capacitor. The recommended CF is 1 µF for 30 Hz

PWM operation.

3.3 SMBus Serial Clock Input (SCLK)

Clocks data into and out of the TC654/TC655. See

Section 5.0 for more information on the serial interface.

3.4 Serial Data (Bi-directional) (SDA)

Serial data is transferred on the SMBus in both direc-

tions using this pin. See Section 5.0 for more informa-

tion on the serial interface.

3.5 Digital (Open Drain) Output

(FAULT)

When the fan’s RPM falls below the user-set RPM

threshold (or OTF occurs with TC655), a logic low sig-

nal is asserted.

3.6 Analog Input (SENSE2)

Fan current pulses are detected at this pin. These

pulses are counted and used in the calculation of the

fan2 RPM.

3.7 Analog Input (SENSE1)

Fan current pulses are detected at this pin. These

pulses are counted and used in the calculation of the

fan1 RPM.

3.8 Digital Output (VOUT)

This active high complimentary output drives the base

of an external transistor or the gate of a MOSFET.

3.9 Power Supply Input (VDD)

The VDD pin with respect to GND provides power to the

device. This bias supply voltage may be independent of

the fan power supply.

DS21734A-page 8

 2002 Microchip Technology Inc.

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