MC1066

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7

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.

Figure 1. Temperature vs. Setpoint Event Generation

EXT_HLIM

EXT_TEMP

ALERT

ASSERT

ALERT

ASSERT

ALERT

TIME

INT_TEMP

INT_HLIM

EXT_LLIM

INT_LLIM

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.

ASSERT

ALERT

ASSERT

OS

RELEASE

OS

ASSERT

ALERT

CRITICAL

COMP

OS

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.