TC670

Features:

• Fan Wear-out Detection for 2-Wire Linear Controlled Fans
• Replacement System for 3-Wire Fans
• Fan Alert Signal when Fan Speed is below Programmed Threshold
• CLEAR Capability for Eliminating False Alarm
• Low Operating Current, 90µA (typ.)
• V_DD Range 3.0V to 5.5V
• Available in a 6-Pin SOT-23 Package




Application

• Protection for Linear Controlled Fans
• Power Supplies
• Industrial Equipment
• PCs and Notebooks
• Data Storage
• Data Communications Equipment
• Instrumentation




Pinout






Specifications

Parameter Name	Value
Typical Accuracy (°C)	N/A
Over Temp Alert	NO
SM Bus	NO
Predictive Fan Fault	yes
Max. Supply Current (A)	150
Max. Accuracy @ 25°C (°C)	N/A
Integrated Temp Sensor	No
Fan Sense	Yes
External Temp Input	No
Auto Shutdown	No
Device Description	Predictive Fan Fault Detector
Temp Range (°C)	-40 to +85
Vcc Range (V)	+3.0 to +5.5

V_DD.......................................................................................6.0V
All inputs and outputs w.r.t. ......... (GND − 0.3V) to (V_DD + 0.3V)
Difference Input voltage ........................................... IV_DD - GND
Output Short Circuit Current ......................................continuous
Current at Input Pin ....................................................... +/-2 mA
Current at Output Pin ................................................... +/-25 mA
Junction Temperature, T_J .................................................... 150
ESD protection on all pins................................................... 4 kV
Operating Temperature Range...............................-40 to +85
Storage Temperature Range ...............................-55 to +150

Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operation sections of the specifications is not implied. Exposure to Absolute Maximum Rating conditions for extended periods may affect device reliability.

Description

The TC670 is an integrated fan speed sensor that predicts and/or detects fan failure, preventing thermal damage to systems with cooling fans. When the fan speed falls below a user specified level, the TC670 asserts an ALERT signal. With this design, a critical minimum fan speed is determined by the user. The fan alert level is then set with a resistor divider on the THRESHOLD pin of the TC670. When the minimum fan speed is reached, the ALERT pin changes from a digital HIGH to LOW. This failure detection works with all linear controlled 2-wire fans. The TC670 eliminates the need for 3-wire fan solutions.
A CLEAR option can be used to reset the ALERT signal, allowing the flexibility of connecting the ALERT output of the TC670 with other Alert/Fault interrupts in the system. This feature can be implemented so that false fan fault conditions do not initiate system shutdown. The TC670 is specified to operate over the full industrial temperature range of -40°C to 85°C. The TC670 is offered in a SOT23-6 pin package and consumes 90uA (typ) during operation. The space saving package and low power consumption make this device an ideal choice for systems requiring fan speed monitoring. The TC670 is an integrated fan speed sensor that predicts and/or detects fan failure, preventing thermal damage to systems with cooling fans. When the fan speed falls below a user specified level, the TC670 asserts an ALERT signal. The TC670 is a predictive fan failure detector that asserts a signal whenever the fan's RPM falls below a user-programmable RPM level.