High-Accuracy PWM Output Temperature Sensors

The MAX6666/MAX6667 are high-accuracy, low-cost, low-power temperature sensors with a single-wire output. The MAX6666/MAX6667 convert the ambient temperature into a ratiometric PWM output with temperature information contained in the duty cycle of the output square wave. The MAX6666 has a push-pull output and the MAX6667 has an open-drain output.

The MAX6666/MAX6667 operate at supply voltages from +3V to +5.5V. The typical unloaded supply current at 5.0V is 200µA. Both devices feature a single-wire output that minimizes the number of pins necessary to interface with a microprocessor (µP). The output is a square wave with a nominal frequency of 35Hz (±20%) at +25°C. The output format is decoded as follows:

Temperature (°C) = 235 - (400 × t1)/t2

Where t1 is fixed with a typical value of 10ms and t2 is modulated by the temperature (Figure 1 in the full data sheet). The MAX6666/MAX6667 operate from -40° to +125° and are available in space-saving SOT23 packages.Applications

* HVAC and Environmental Control * Industrial * Process Control * µP and µC Temperature Monitoring

* Simple Single-Wire PWM Output

* ±1.0°C Accuracy at +25°C

* High Accuracy

* ±1°C at TA = +30°C

* ±2.5°C at TA = +10°C to +50°C

* Operate Up to +125°C

* Low 200µA Typical Current Consumption

* Small SOT23 package