FACTORY-PROGRAMMED, REMOTE TEMPERATURE SWITCHES WITH FAN CONTROLLER/DRIVER PROVIDE RELIABLE SYSTEM PROTECTION
SUNNYVALE, CA-October 2, 2001-Maxim Integrated Products introduces the MAX6668 and MAX6670 fan controllers with a remote-junction thermal switch and an internal power transistor for driving a cooling fan. The MAX6668 is housed in a small 8-pin µMAX package, and the MAX6670 is housed in a 10-pin µMAX package. Both devices monitor temperature of an external diode-connected transistor and activate the FANOUT pin to power the fan when temperature rises above a factory-programmed threshold. The external sensor transistor can be either discrete or integrated onto another IC’s die (e.g. a microprocessor or ASIC). Ideal for 5V or 12V brushless DC cooling fans, the MAX6668/MAX6670 can drive a fan rated up to 250mA.
The MAX6668/MAX6670 are available with factory-programmed temperature thresholds from +40°C to +75°C in 5°C increments. The fan activation trip point’s accuracy is ±1°C (typ) and ±2.2°C (max) for all trip thresholds. The MAX6670 fan trip point has a pin-selectable hysteresis of 4°C, 8°C, or 12°C, and the MAX6668 has a hysteresis of 8°C. The fan activation threshold and built-in hysteresis create a simple on/off fan-control system.
The MAX6668 and MAX6670 are equipped with an overtemperature output, WARN, which is activated when the temperature is 15°C above the fan activation threshold. The MAX6670 is also equipped with an additional over-temperature output, OT, which is activated when the temperature is 30°C above the fan activation threshold. These features can be used to safely power down systems that are overheated.
The fan control loop can be overridden and the fan can be turned on at any time by setting the FORCEON pin low.
The MAX6668/MAX6670 operate with a supply voltage between 3.0V and 5.5V and have an unloaded supply current of just 110µA (typ). Both devices operate over the automotive temperature range (-40°C to +125°C).
Prices start at $1.11 for the MAX6668 and $1.24 for the MAX6670 (1000-up, FOB USA).
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