LM87 datasheet(2/32 Pages) NSC

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Block Diagram

10099501

Pin Description

Name(s)

Number

of Pins

Type

Description

ADD/NTEST_OUT

Digital I/0

This pin normally functions as a three-state input that controls the

two LSBs of the Serial Bus Address. When this pin is tied to V

the two LSBs are 01. When tied to Ground, the two LSBs are 10. If

this pin is not connected, the two LSBs are 00. This pin also

functions as an output during NAND Tree tests (board-level

connectivity testing). To ensure proper NAND tree function, this pin

should not be tied directly to V

CC or Ground. Instead, a series 5 k

Ω

resistor should be used to allow the test output function to work.

Refer to SECTION 11 on NAND Tree testing.

THERM#

Digital I/O

This pin functions as an open-drain interrupt output for temperature

interrupts only, or as an interrupt input for fan control. It has an

on-chip 100 k

Ω pullup resistor.

SMBData

Digital I/O

Serial Bus bidirectional Data. Open-drain output.

SMBCLK

Digital Input

Serial Bus Clock.

FAN1/AIN1-

FAN2/AIN2

5-6

Analog/Digital

Inputs

Programmable as analog inputs (0 to 2.5V) or digital Schmitt

Trigger fan tachometer inputs.

Digital I/O

An active high input from an external circuit which latches a

Chassis Intrusion event. This line can go high without any clamping

action regardless of the powered state of the LM87. There is also

an internal open-drain output on this line, controlled by Bit 7 of the

CI Clear Register (46h), to provide a minimum 20 ms pulse.

LM87 Datasheet(PDF) 2 Page - National Semiconductor (TI)

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