Remote/Local Temperature Sensor with SMBus Serial Interface

The MAX1617A is a precise digital thermometer that reports the temperature of both a remote sensor and its own package. The remote sensor is a diode-connected transistor-typically a low-cost, easily mounted 2N3904 NPN type-that replaces conventional thermistors or thermocouples. Remote accuracy is ±3°C for multiple transistor manufacturers, with no calibration needed. The remote channel can also measure the die temperature of other ICs, such as microprocessors, that contain an on-chip, diode-connected transistor.

The 2-wire serial interface accepts standard System Management Bus (SMBus) Write Byte, Read Byte, Send Byte, and Receive Byte commands to program the alarm thresholds and to read temperature data. The data format is 7 bits plus sign, with each bit corresponding to 1°C, in two's complement format. Measurements can be done automatically and autonomously, with the conversion rate programmed by the user or programmed to operate in a single-shot mode. The adjustable rate allows the user to control the supply-current drain.

The MAX1617A is nearly identical to the popular MAX1617, but has improved SMBus timing specifications, improved bus collision immunity, software manufacturer and device identification available via the serial interface, and a power-on reset function that can force a reset of the slave address via the serial interface.

Applications

* Central Office Telecom Equipment * Computers: Desktop, Workstation, Server * Industrial Controls * LAN Servers * Multichip Modules * Smart Battery Packs/Chargers * Test and Measurement Equipment

* Two Channels: Measures Both Remote and Local Temperatures

* No Calibration Required

* SMBus 2-Wire Serial Interface

* Programmable Under/Overtemperature Alarms

* Supports SMBus Alert Response

* Supports Manufacturer and Device ID Codes

* Accuracy

* ±2°C (+60°C to +100°C, local)

* ±3°C (-40°C to +125°C, local)

* ±3°C (+60°C to +100°C, remote)

* 3µA (typ) Standby Supply Current

* 70µA (max) Supply Current in Auto-Convert Mode

* +3V to +5.5V Supply Range

* Small 16-Pin QSOP Package