Multichannel Remote/Local Temperature Sensors

The MAX1668/MAX1805/MAX1989 are precise multichannel digital thermometers that report the temperature of all remote sensors and their own packages. The remote sensors are diode-connected transistorstypically low-cost, easily mounted 2N3904 NPN typesthat replace conventional thermistors or thermocouples. Remote accuracy is ±3°C for multiple transistor manufacturers, with no calibration needed. The remote channels 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.

The MAX1668/MAX1805/MAX1989 are available in small, 16-pin QSOP surface-mount packages. The MAX1989 is also available in a 16-pin TSSOP.

Applications

* Central Office Telecom Equipment * Desktop/Notebook Computers * Industrial Controls * LAN Servers * Multichip Modules * Test and Measurement Equipment

* Multichannel

* 4 Remote, 1 Local (MAX1668/MAX1989)

* 2 Remote, 1 Local (MAX1805)

* No Calibration Required

* SMBus 2-Wire Serial Interface

* Programmable Under/Overtemperature Alarms

* Supports SMBus Alert Response

* 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

* 700µA (max) Supply Current

* Small, 16-Pin QSOP/TSSOP Packages