The MAX6682 converts an external thermistor’s temperature-
dependent resistance directly into digital form.
The thermistor and an external fixed resistor form a voltage-
divider that is driven by the MAX6682’s internal
voltage reference. The MAX6682 measures the voltage
across the external resistor and produces a 10-bit +
sign output code dependent on that voltage.
The MAX6682 does not linearize the highly nonlinear
transfer function of a typical negative temperature coefficient
(NTC) thermistor, but it does provide linear output
data over limited temperature ranges when used
with an external resistor of the correct value. Over the
0° to +50°C temperature range, the MAX6682 produces
output data that is scaled to 8LSBs/°C (for 0.125°C resolution),
provided that the correct thermistor and external
resistor values are used. Other temperature ranges
can be easily accommodated, but do not necessarily
yield data scaled to an even number of LSBs per
degree.
The 3-wire SPI?-compatible interface can be readily
connected to a variety of microcontrollers.
The MAX6682 is a read-only device, simplifying use in
systems where only temperature data is required.
Power-management circuitry reduces the average thermistor
current, minimizing self-heating. Between conversions,
supply current is reduced to 21μA (typ). The
internal voltage reference is shut down between measurements.
The MAX6682 is available in a small, 8-pin μMAX package
and is specified over the -55°C to +125°C temperature
range.
Applications
HVAC
Medical Devices
Battery Packs/Chargers
Home Appliances