M
TC664/TC665
SMBus™ PWM Fan Speed Controllers With
Fan Fault Detection
Features
• Temperature Proportional Fan Speed for Reduced
Acoustic Noise and Longer Fan Life
• FanSense™ Protects against Fan Failure and
Eliminates the Need for 3-wire Fans
• Over Temperature Detection (TC665)
• Efficient PWM Fan Drive
• Provides RPM Data
• 2-Wire SMBus™-Compatible Interface
• Supports Any Fan Voltage
• Software Controlled Shutdown Mode for "Green"
Systems
• Supports Low Cost NTC/PTC Thermistors
• Space Saving 10-Pin MSOP Package
• Temperature Range: -40°C to +85ºC
Applications
• Personal Computers & Servers
• LCD Projectors
• Datacom & Telecom Equipment
• Fan Trays
• File Servers
• Workstations
www.DataShee•t4GU.ecnoemral Purpose Fan Speed Control
Package Type
10-Pin MSOP
VIN 1
CF 2
SCLK 3
SDA 4
GND 5
TC664
TC665
10 VDD
9 VOUT
8 SENSE
7 NC
6 FAULT
Description
The TC664/TC665 devices are PWM mode fan speed
controllers with FanSense technology for use with
brushless DC fans. These devices implement temper-
ature proportional fan speed control which lowers
acoustic fan noise and increases fan life. The voltage
at VIN (Pin 1) represents temperature and is typically
provided by an external thermistor or voltage output
temperature sensor. The PWM output (VOUT) is
adjusted between 30% and 100%, based on the volt-
age at VIN. The PWM duty cycle can also be pro-
grammed via SMBus to allow fan speed control without
the need for an external thermistor. If VIN is not con-
nected, the TC664/TC665 will start driving the fan at a
default duty cycle of 39.33%. See Section 4.3, "Fan
Startup", for more details).
In normal fan operation, a pulse train is present at the
SENSE pin (Pin 8). The TC664/TC665 use these
pulses to calculate the fan revolutions per minute
(RPM). The fan RPM data is used to detect a worn out,
stalled, open or unconnected fan. An RPM level below
the user-programmable threshold causes the TC664/
TC665 to assert a logic low alert signal (FAULT). The
default threshold value is 500 RPM. Also, if this condi-
tion occurs, FF (bit 0<0>) in the Status Register will also
be set to a ‘1’.
An over-temperature condition is indicated when the
voltage at VIN exceeds 2.6 V (typical). The TC664/
TC665 devices indicate this by setting OTF(bit 5<X>) in
the Status Register to a '1'. The TC665 device also
pulls the FAULT line low during an over-temperature
condition.
The TC664/TC665 devices are available in a 10-Pin
MSOP package and consume 150 µA during opera-
tion. The devices can also enter a low-power shutdown
mode (5 µA, typ.) by setting the appropriate bit in the
Configuration Register. The operating temperature
range for these devices is -40°C to +85ºC.
SMBus is a trademark of Intel Coporation
2002 Microchip Technology Inc.
DS21737A-page 1
