TC648_13 Datasheet, PDF (1/28 Pages) Microchip Technology – Fan Speed Controller with Auto-Shutdown and Over-Temperature Alert

TC648
Fan Speed Controller with Auto-Shutdown
and Over-Temperature Alert
Features
• Temperature Proportional Fan Speed for Acoustic
Control and Longer Fan Life
• Efficient PWM Fan Drive
• 3.0V to 5.5V Supply Range:
- Fan Voltage Independent of TC648
Supply Voltage
- Supports any Fan Voltage
• Over-temperature Fault Detection
• Automatic Shutdown Mode for “Green” Systems
• Supports Low Cost NTC/PTC Thermistors
• Space Saving 8-Pin MSOP Package
Applications
• Power Supplies
• Computers
• Portable Computers
• Telecom Equipment
• UPSs, Power Amps
• General Purpose Fan Speed Control
Available Tools
• Fan Controller Demonstration Board (TC642DEMO)
• Fan Controller Evaluation Kit (TC642EV)
Package Types
SOIC/PDIP/MSOP
V_{IN 1}
C_F 2
V_{AS 3}
GND 4
TC648
8 ^VDD
7 ^VOUT
6 _OTF
5 NC
General Description
The TC648 is a switch mode, fan speed controller for
use with brushless DC fans. Temperature proportional
speed control is accomplished using pulse width mod-
ulation (PWM). A thermistor (or other voltage output
temperature sensor) connected to the V_IN input
furnishes the required control voltage of 1.25V to 2.65V
(typical) for 0% to 100% PWM duty cycle. The TC648
can be configured to operate in either auto-shutdown or
minimum speed mode. In auto-shutdown mode, fan
operation is automatically suspended when measured
temperature (V_IN) is lower than a user programmed
minimum setting (V_AS). The fan is automatically
restarted, and proportional speed control restored,
when V_IN exceeds V_AS (plus hysteresis). Operation in
minimum speed mode is similar to auto-shutdown
mode, with the exception that the fan is operated at a
user programmed minimum setting when the mea-
sured temperature is low. An integrated Start-up Timer
ensures reliable motor start-up at turn-on, and when
coming out of shutdown or auto-shutdown mode.
The over-temperature fault output (OTF) is asserted
when the PWM reaches 100% duty cycle, indicating a
possible thermal runaway situation.
The TC648 is available in the 8-pin plastic DIP, SOIC
and MSOP packages and is available in the industrial
and extended commercial temperature ranges.
 2001-2012 Microchip Technology Inc.
DS21448D-page 1