TC647_13 Datasheet, PDF (1/28 Pages) Microchip Technology – PWM Fan Speed Controller with FanSense™ Technology

TC647
PWM Fan Speed Controller with FanSense^™ Technology
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 TC647
Supply Voltage
- Supports any Fan Voltage
• FanSense™ Technology Fault Detection Circuits
Protect Against Fan Failure and Aid System
Testing
• Shutdown Mode for "Green" Systems
• Supports Low Cost NTC/PTC Thermistors
• Space Saving 8-Pin MSOP Package
Applications
• Power Supplies
• Personal Computers
• File Servers
• 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_{MIN 3}
GND 4
TC647
8 V_DD
7 V_OUT
6 FAULT
5 SENSE
General Description
The TC647 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 V_IN furnishes the
required control voltage of 1.25V to 2.65V (typical) for
0% to 100% PWM duty cycle. Minimum fan speed is
set by a simple resistor divider on the V_MIN input. An
integrated Start-up Timer ensures reliable motor start-
up at turn-on, coming out of shutdown mode or
following a transient fault. A logic low applied to V_MIN
(Pin 3) causes fan shutdown.
The TC647 also features Microchip Technology's pro-
prietary FanSense™ technology for increasing system
reliability. In normal fan operation, a pulse train is pres-
ent at SENSE (Pin 5). A missing pulse detector moni-
tors this pin during fan operation. A stalled, open or
unconnected fan causes the TC647 to trigger its Start-
up Timer once. If the fault persists, the FAULT output
goes low and the device is latched in its shutdown
mode.
The TC647 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.
DS21447D-page 1