MC1066 Datasheet, PDF (7/16 Pages) ON Semiconductor – ACPI-Compliant SMBus Temperature Sensor with Internal and External Diode Input

MC1066
DETAILED OPERATING DESCRIPTION
The MC1066 acquires and converts temperature
information from two separate sources, both silicon junction
diodes, with a basic accuracy of ±1°C. One is located on the
MC1066 die; the other is connected externally. This external
diode may be located on another IC die. The
analog–to–digital converter on the MC1066 alternately
converts temperature data from the two sensors and stores
them separately in internal registers.
ASSERT
OS
RELEASE
OS
EXT_TEMP
INT_TEMP
CRITICAL
ASSERT
ALERT
ASSERT
ALERT
EXT_HLIM
ASSERT
ALERT INT_HLIM
ASSERT
ALERT
EXT_LLIM
The system interface is a slave SMBus port with an
ALERT (SMBALERT) and COMP interrupt outputs. The
ALERT interrupt is triggered when one or more of four
preset temperature thresholds are tripped (see Figure 1).
These four thresholds are user–programmable via the
SMBus port. The COMP interrupt is triggered when
EXT_TEMP equals or exceeds EXT_HLIM. Also, there is
a fifth independent, hardware programmable threshold
(CRITICAL) that trips its own interrupt (OS) for an
unconditional warning. Additionally, the temperature data
can be read at any time through the SMBus port. Nine
SMBus addresses are programmable for the MC1066,
which allows for a multi–sensor configuration. Also, there
is low–power Standby mode where temperature acquisition
is suspended.
INT_LLIM
TIME
ALERT
COMP
OS
Note: This diagram implies that the appropriate setpoint is moved,
temporarily, after each ALERT event to suppress re–assertion
of ALERT immediately after the ARA/de–assertion.
Figure 1. Temperature vs. Setpoint Event Generation
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