MAX6648

The MAX6648/MAX6692 are precise, two-channel digi-tal temperature sensors. They accurately measure the temperature of their own die and a remote PN junction,and report the temperature in digital form using a 2-wireserial interface. The remote PN junction is typically theemitter-base junction of a common-collector PNP on aCPU, FPGA, or ASIC.

The 2-wire serial interface accepts standard SystemManagement Bus (SMBus)(TM) write byte, read byte,send byte, and receive byte commands to read thetemperature data and to program the alarm thresholds.To enhance system reliability, the MAX6648/MAX6692include an SMBus timeout. A fault queue prevents theALERT and OVERT outputs from setting until a fault hasbeen detected one, two, or three consecutive times(programmable).

The MAX6648/MAX6692 provide two system alarms:ALERT and OVERT . ALERT asserts when any of four tem-perature conditions are violated: local overtemperature,remote overtemperature, local undertemperature, orremote undertemperature. OVERT asserts when the tem-perature rises above the value in either of the two OVERT limit registers. The OVERT output can be used to activatea cooling fan, or to trigger a system shutdown.

Measurements can be done autonomously, with theconversion rate programmed by the user, or in a single-shot mode. The adjustable conversion rate allows theuser to optimize supply current and temperatureupdate rate to match system needs.

Remote accuracy is ±0.8 maximum error between+25 and +125 with no calibration needed. The MAX6648/MAX6692 operate from -55 to +125, andmeasure temperatures between 0 and +125. TheMAX6648 is available in an 8-pin MAX package, and theMAX6692 is available in 8-pin MAX and SO packages.