The DS1852 transceiver monitor manages all system monitoring functions in a fiber optic data transceiver module, in accordance with proposal SFF-8472. Its functions include 2-wire communications with the host system, EEPROM memory for identification, tracking, and calibration, an ADC with four muxing inputs, three fast comparators, and a temperature sensor to monitor an optical transceiver. The DS1852 has programmable alarm and warning flags for all four analog-to-digital (A/D) conversion values (three user analog inputs plus supply voltage) as well as the temperature. These conditions can be used to determine critical parameters inside each module. The three fast comparators have temperaturecompensated programmability. The temperature dependencies of the trip points aid in assessing critical conditions.