MAX6654

Desktop Computers
Notebook Computers
Servers
Thin Clients
Workstations
Test and Measurement
Multichip Modules
SMBus is a trademark of Intel Corp.
I²C is a trademark of Philips Corp.
⁺Patents pending

(All voltages are referenced to GND unless otherwise noted.)
Vcc .........................................................................-0.3V to +6V
DXP, ADD_ ................................................-0.3V to (VCC + 0.3V)
DXN .....................................................................-0.3V to +0.8V
SMBCLK, SMBDATA, ALERT, STBY.. ..........................-0.3V to +6V
SMBDATA, ALERT Current ...................................-1mA to +50mA
DXN Current .....................................................................±1mA
ESD Protection (all pins, Human Body Model). .................2000V
Continuous Power Dissipation (TA = +70°C)
16-Pin QSOP (derate 8.30mW/°C above +70°C).........667mW
Operating Temperature Range ....................-55°C to +125°C
Junction Temperature...................................................+150°C
Storage Temperature Range ........................-65°C to +165°C
Lead Temperature (soldering, 10s) ..............................+300°C

Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

The MAX6654† is a precise digital thermometer that reports the temperature of both a remote P-N junction and its own die. The remote junction can be a diode-connected transistor-typically a low-cost, easily mounted 2N3904 NPN type or 2N3906 PNP type-that replaces conventional thermistors or thermocouples. Remote accuracy of MAX6654 is ±1°C for multiple transistor anufacturers,with no calibration needed. The remote junction of MAX6654 can also be a common-collector PNP, such as a substrate PNP of a microprocessor (P).

The 2-wire serial interface of MAX6654 accepts standard Syste Management Bus (SMBus)TM, Write Byte, Read Byte, Send Byte, and Receive Byte commands to program the alarm thresholds and to read temperature data. 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 conversion rate of MAX6654 allows the user to optimize supply current and temperature update rate to match system needs. When the conversion rate is faster than 1Hz, the conversion results are available as a 7-bitplus- sign yte with a 1°C LSB. When the conversion rate is 1Hz or slower, the MAX6654 enters the extended mode. In this mode, 3 dditional bits of temperature data are available in the extended resolution register, providing 10-bit-plus-sign resolution with a 0.125°C LSB. Single-shot conversions also ave .125°C per LSB resolution when the conversion rate is 1Hz or slower.

A parasitic resistance cancellation (PRC) mode of MAX6654 can also be invoked for conversion rates of 1Hz or slower by setting bit 4 of the configuration register to 1. In PRC mode, the effect of series resistance on the leads of the external diode is canceled. The 11-bit conversion of MAX6654 in PRC mode is performed in <500ms and is disabled for conversion rates faster than 1Hz. The one-shot conversion is also 11 bits in <500ms.

The MAX6654 default low-temperature measurement limit is 0°C. This can be extended to -64°C by setting bit 5 of the configuration register to 1. The MAX6654 is available in a small, 16-pin QSOP surface- mount package.