The MAX6646/MAX6647/MAX6649 are precise, two-channel
digital temperature sensors. The devices accurately
measure the temperature of their own die and a
remote PN junction, and report the temperature in digital
form using a 2-wire serial interface. The remote PN junction
is typically the emitter-base junction of a common-collector
PNP on a CPU, FPGA, or ASIC.
The 2-wire serial interface accepts standard system management
bus (SMBus™) write byte, read byte, send byte,
and receive byte commands to read the temperature
data and to program the alarm thresholds. To enhance
system reliability, the MAX6646/MAX6647/MAX6649
include an SMBus timeout. A fault queue prevents the
active-low ALERT and active-low OVERT outputs from setting until a fault has
been detected one, two, or three consecutive times
(programmable).
The MAX6646/MAX6647/MAX6649 provide two system
alarms: active-low ALERT and active-low OVERT. Active-low ALERT asserts when any of four temperature conditions are violated: local overtemperature,
remote overtemperature, local undertemperature,
or remote undertemperature. Active-low OVERT asserts when
the temperature rises above the value in either of the two
active-low OVERT limit registers. The active-low OVERT output can be used to
activate a cooling fan, or to trigger a system shutdown.
Measurements can be done autonomously, at the programmed
conversion rate, or in a single-shot mode. The
adjustable conversion rate allows optimizing supply current
and temperature update rate to match system needs.
Remote accuracy is ±1°C maximum error between +60°C
and +145°C with no calibration needed. The MAX6646/MAX6647/MAX6649 operate from -55°C to +125°C, and measure temperatures between 0°C and +145°C. The MAX6646/MAX6647/MAX6649 are available in an 8-pin
µMAX® package.
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