The TMP03* is a complete temperature data-acquisition system on a monolithic silicon chip. Including a silicon-based sensor, internal voltage reference, and sigma-delta A/D converter, it fits in a 3-pin (power, common, and output) TO-92 transistor package. Its digital output is a low-frequency variable-duty-cycle serial data stream, available at an open collector with 5-mA sink-current available. A companion product, the TMP04, is identical but has a CMOS/TTL-compatible output.
Analog Devices bandgap references generate both a constant voltage and a PTAT (proportional to absolute temperature) voltage. In the TMP03, these are applied as inputs to a first-order sigma-delta modulator. The device output is a 35-Hz (nominal) accurate