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10.0 Temperature Sensor (TMS)

10.1 OVERVIEW

The Temperature Sensor (TMS) is a diode input temperature sensor that consists of a Delta-Sigma Analog to Digital (A/D)

converter and a digital overtemperature detector. Both of these elements conform to Advance Configuration and Power In-

terface (ACPI) requirements for thermal management.

The TMS senses the temperature of two target ICs by measuring the voltage drop of diode(s) placed on the target IC’s die.

A host can query the TMS at any time to read the temperature of the remote diode(s). An ALERT interrupt output becomes

active when the temperature goes above THIGH or below TLOW. The host may program the two thresholds for each sensing

channel to define an operation window. Overtemperature Shutdown (OTS) output becomes active when the temperature

exceeds the programmable limit TOS.

10.2 FUNCTIONAL DESCRIPTION

The TMS incorporates a band-gap temperature sensor using remote diode(s) and an 8-bit Delta-Sigma Analog-to-Digital

Converter (A/D converter). Once enabled and put in active (non-standby mode), the TMS continuously measures tempera-

ture of up to two remote diodes. TMS readings are available at all times via the host interface. When SLPS3 input becomes

inactive, the conversion is stopped and no new results are generated until both SLPS3 becomes active and the internal wake

up sequence is completed. TMS registers are maintained by VSB during this period.

A digital comparator is also incorporated to compare temperature readings to user-programmable limits. OTS output indi-

cates that the result of the comparison exceeds the limit preset in the Channel Overtemperature Limit register. ALERT output

indicates that the result of the comparison is not within limits preset in the Channel Temperature High or Low Limit (CHTH

and CHTL) registers.

Figure 33 shows a simplified block diagram of the TMS. It represents only one remote diode (even though there are actually

two remote diodes and one or two OTS signals, one for each diode sensor or combined).

Figure 33.

TMS Simpliﬁed Block Diagram

Temperature

Sensor

Circuitry

DPi

DNi

∆−Σ

8-Bit

A/D Converter

Diode

Selector

Control

Logic

Temperature

Readout

Overtemp.

Shutdown

Setpoint

High and

Low Limit

Setpoints

Conversion

Rate

OTS

IRQ

SMI

TMS Module

ALERT

Overtemp

High

Low

Enable

and

Config

Logic

Enable

Bits

VDD

VSS

VSB

PC87365 Datasheet(PDF) 169 Page - National Semiconductor (TI)

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