TC648

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




Application

• Power Supplies
• Computers
• Portable Computers
• Telecom Equipment
• UPSs, Power Amps
• General Purpose Fan Speed Control




Pinout






Specifications

Parameter Name	Value
Typical Accuracy (°C)	Depends on external thermistor
Over Temp Alert	yes
SM Bus	NO
Predictive Fan Fault	NO
Max. Supply Current (A)	1000
Max. Accuracy @ 25°C (°C)	Depends on external thermistor
Integrated Temp Sensor	No
Fan Sense	No
External Temp Input	Yes
Auto Shutdown	Yes
Device Description	Fan Manager
Temp Range (°C)	-40 to +85
Vcc Range (V)	+3.0 to +5.5

Supply Voltage .........................................................6V
Input Voltage, Any Pin... (GND 0.3V) to (V_DD + 0.3V)
Package Thermal Resistance:
PDIP (R_JA)......................................................125°C/W
SOIC (R_JA) ....................................................155°C/W
MSOP (R_JA) ...................................................200°C/W
Specified Temperature Range ........... -40°C to +125°C
Storage Temperature Range.............. -65°C to +150°C




Description

The TC648 is a switch mode fan speed controller for use with brushless DC motors. Temperature proportional speed control is accomplished using pulse width modulation(PWM). A thermistor (or other voltage output temperature sensor) connected to the VIN 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 (VIN) is lower than a user-programmed minimum setting (VAS). The fan is automatically restarted and proportional speed control restored when VIN exceeds VAS (plus hysteresis). Operation in Minimum Speed mode is similar to Auto-Shutdown mode, except the fan of TC648 is operated at a user-programmed minimum setting when measured temperature is low. An integrated Start-Up Timer ensures reliable motor start-up at turn-on, or when coming out of Shutdown mode. The over-temperature fault (OTF) is asserted when the PWM reaches 100% duty cycle, indicating a possible thermal runaway situation. The TC648 is packaged in a space-saving 8-pin plastic DIP, MSOP or SOIC package and is available in the industrial temperature range.