MAX6691

Vcc to GND...........................................................-0.3V to +6.0V
All Other Pins to GND.................................-0.3V to (VCC + 0.3V)
I/O, R+, R-, T1T4 Current..............................................±20mA
ESD Protection (Human Body Model) .............................±2000V
Continuous Power Dissipation (TA = +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C) ........444.4mW
Operating Temperature Range ....................-55°C to +125°C
Junction Temperature...................................................+150°C
Storage Temperature Range .......................-65°C to +150°C
Lead Temperature (soldering, 10s) .............................+300°C

Stresses beyond 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 beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

The MAX6691 four-channel thermistor temperature-topulse- width converter measures the temperatures of up to four thermistors and converts them to a series of output pulses whose widths are related to the thermistors'temperatures. Each of the four thermistors and an external fixed resistor (REXT) form a voltage-divider that is driven by the MAX6691's internal voltage reference (VREF). VREF and the voltage across REXT are measured and converted to a pulse.

The MAX6691 has a single open-drain I/O pin that can be readily connected to a variety of microcontrollers. The microcontroller initiates a conversion by pulling the I/O pin low and releasing it. When conversion is done, the MAX6691 signals the end of conversion by pulling the I/O pin low once again. The pulse corresponding to
the first thermistor is sent immediately after the release of the I/O pin.

The on-chip power-management circuitry reduces the average thermistor current to minimize errors due to thermistor self-heating. Between conversions, the MAX6691 falls into a 10A (max) sleep mode, where the voltage reference is disabled and the supply current is at its minimum.

The MAX6691 is available in a 10-pin MAX package and is specified from -55°C to +125°C temperature range.