Low Voltage, Resistor Programmable Thermostatic Switch

The AD22105 is a solid state thermostatic switch. Requiring only one external programming resistor, the AD22105 can be set to switch accurately at any temperature in the wide operating range of -40°C to +150°C. Using a novel circuit architecture, the AD22105 asserts an open collector output when the ambient temperature exceeds the user-programmed setpoint temperature. The AD22105 has approximately 4°C of hysteresis which prevents rapid thermal on/off cycling.

The AD22105 is designed to operate on a single power supply voltage from +2.7 V to +7.0 V facilitating operation in battery powered applications as well as in industrial control systems. Because of low power dissipation (230 µW @ 3.3 V), self-heating errors are minimized and battery life is maximized.

An optional internal 200 k(ohm) pull-up resistor is included to facilitate driving light loads such as CMOS inputs.

Alternatively, a low power LED indicator may be driven directly.

APPLICATIONS

* Industrial process control

* Thermal control systems

* CPU monitoring

* Computer thermal management circuits

* Fan control

* Handheld/portable electronic equipment

* User-programmable temperature setpoint

* ±2.0°C maximum ambient setpoint accuracy

* 4.1°C typical hysteresis