TC646B

The TC646B is a new version of the existing TC646 fan speed controller. This device is a switch mode fan speed controller, which incorporates a new fan auto restart function. Temperature proportional speed control is accomplished using pulse width modulation. A thermistor (or other voltage output temperature sensor) connected to the VIN input supplies the required control voltage of 1.20V to 2.60V (typical) for 0% to 100% PWM duty cycle. The auto-shutdown speed is set by a simple resistor divider on the VAS input. An integrated Start-Up Timer ensures reliable fan motor start-up at turn-on, coming out of shutdown mode, auto-shutdown mode, or following a transient fault. A logic low applied to VIN, pin 1, causes fan shutdown.

The TC646B also features Microchip Technology's proprietary FanSense™ technology for increasing system reliability. In normal fan operation, a pulse train is present at SENSE, pin 5. A missing-pulse detector monitors this pin during fan operation. A stalled, open, or unconnected fan causes the TC646B device to turn the VOUT output on full (100% duty cycle). If the fan fault persists (a fan current pulse is not detected within a 32/F period), the FAULT output goes low. Even with the FAULT output low, the VOUT output is on full during the fan fault condition in order to try and restart the fan. The FAULT signal is also asserted if the PWM reaches 100% duty cycle, indicating that maximum cooling capability has been reached and a possible thermal runaway condition exists.

Features
  • Temperature Proportional Fan Speed for Acoustic Control and Longer Fan Life
  • FanSense™ Protects Against Fan Failure
  • Efficient PWM Drive
  • Automatic Shutdown Mode for "Green" Systems
  • 3.0V to 5.5V Supply Range
  • Fan Voltage Independent of Supply Voltage – Supports Any Fan Voltage
  • Supports Low Cost NTC/PTC Thermistors
  • Fan Auto-Restart
  • Over-Temperature Indication
Parameter
Parameter Name Value Value
Device Description Fan Manager Fan Manager
Typical Accuracy (°C) Depends on external thermistor Depends on external thermistor
Over Temp Alert yes yes
Max. Supply Current (µA) 400 400
Max. Accuracy @ 25°C (°C) Depends on external thermistor Depends on external thermistor
Fan Sense Yes Yes
External Temp Input Yes Yes
Auto Shutdown Yes Yes
High/Low PWM Freq Low Low
Temp Range (°C) -40 to +85 -40 to +85
Vcc Range (V) +3.0 to +5.5 +3.0 to +5.5
Documents
TC646B/TC648B/TC649B DatasheetData Sheets02/05/2013552KB
AN770 - Linear Voltage Fan Speed Control Using Microchip?s TC64x Family (TC642, TC646, TC648)AppNote07/27/2004203KB
AN771 - Suppressing Acoustic Noise in PWM Fan Speed Control SystemsAppNote07/27/2004276KB
TB063 - An Integrated Fan Speed Control Solution Can Lower System Costs, Reduce Acoustic Noise, Power Consumption and Enhance System ReliabilityAppNote02/24/2003204KB
Analog & Interface Guide (Volume 2)Brochures10/11/20051067KB
Quick Guide to Microchip Development ToolsBrochures10/15/201411223KB
Fan Control Function Pack Design GuideProduct Line Documents08/23/2006162KB
Fan Management Solutions Product OverviewProduct Line Documents08/23/200687KB
Fan Speed Controller and Fan Fault Detector FamilyProduct Line Documents05/13/2003245KB
Analog & Interface Product Selector GuideProduct Line Card03/21/20164116KB
8-Pin SOIC/MSOP/TSSOP/DIP Evaluation Board User's GuideUser Guides01/24/20061367KB
TC64X/TC64XB Fan Control Evaluation Board User's GuideUser Guides11/24/2003360KB
Thermistor Value Calculator with Solver for the TC64x FamilyUser Guides11/24/2003130KB
Thermistor Value Calculator without Solver for the TC64x FamilyUser Guides11/24/2003107KB
Ordering Information
Part NumberLeadsPackage TypeTemp RangePacking1+26+100+1000+5000+
TC646BEOA8SOIC-40C to +85CTUBE1.160.970.880.850.84
TC646BEOA7138SOIC-40C to +85CT/R1.160.970.880.850.84
TC646BEPA8PDIP-40C to +85CTUBE1.321.101.000.970.96
TC646BEUA8MSOP-40C to +85CTUBE1.211.010.920.890.88
TC646BEUA7138MSOP-40C to +85CT/R1.211.010.920.890.88
Similar Devices
ProductDescriptionTypical Accuracy (º)Temp RangePrice5K
EMC2101±0.5-40 - +125$0.79
EMC2300±0.250 - 70$1.24
EMC6D102±0.250 - 70$1.63
EMC6D103±0.250 - 70$1.80
EMC6D103S±0.250 - 70$1.80
EMC6W201±0.250 - 70$2.19
TC642Fan ManagerDepends on external thermistor-40 - +85$1.02
TC642BFan ManagerDepends on external thermistor-40 - +85$0.84
TC646Fan ManagerDepends on external thermistor-40 - +85$1.02
TC646BFan ManagerDepends on external thermistor-40 - +85$0.84
TC647Fan ManagerDepends on external thermistor-40 - +85$0.94
TC647BFan ManagerDepends on external thermistor-40 - +85$0.84
TC648Fan ManagerDepends on external thermistor-40 - +85$0.85
TC648BFan ManagerDepends on External Thermistor-40 - +85$0.79
TC649Fan ManagerDepends on external thermistor-40 - +85$0.94
TC649BFan ManagerDepends on external thermistor-40 - +85$0.84
TC650Fan Manager1-40 - +125$1.26
TC651Fan Manager1-40 - +125$1.08
TC652Fan Manager1-40 - +125$1.36
TC653Fan Manager1-40 - 125$1.36
TC654Dual SMBus Fan ManagerDepends on external thermistor-40 - +85$1.43
TC655Dual SMBus Fan ManagerDepends on external thermistor-40 - +85$1.53
TC664Single SMBus Fan ManagerDepends on external thermistor-40 - +85$1.27
TC665Single SMBus Fan ManagerDepends on external thermistor-40 - +85$1.31
TC670Predictive Fan Fault DetectorN/A-40 - +85$0.94
RoHS Information
PartNumberDeviceWeightShippingWeightLeadCountPackageTypePackageWidthSolderCompositionJEDECIndicatorRoHSChinaEFUP
TC646BEPA0.4867000.9000008PDIP.300inMatte Tine3
TC646BEOA0.0780000.1600008SOIC.150In(3.90mm)Matte Tine3
TC646BEOA7130.0780000.2303038SOIC.150In(3.90mm)Matte Tine3
TC646BEUA7130.0256000.2156008MSOP3x3mmMatte Tine3
TC646BEUA0.0256000.0700008MSOP3x3mmMatte Tine3
TC646B/TC648B/TC649B Datasheet TC649B
TC646B/TC648B/TC649B Datasheet TC649B
AN770 TC649B
AN771 TC649B
TB063 TC649B
Analog & Interface Guide (Volume 2) MCP23S08
Quick Guide to Microchip Development Tools ENC28J60
Fan Control Function Pack Design Guide TC670
Fan Management Solutions Product Overview TC670
Fan Speed Controller and Fan Fault Detector Family TC665
Analog & Interface Product Selector Guide ENC624J600
8-Pin SOIC/MSOP/TSSOP/DIP Evaluation Board User's Guide SOIC8EV
TC64X/TC64XB Fan Control Evaluation Board User's Guide TC649B