LM81 datasheet(3/32 Pages) NSC

3 / 32 page

Pin Description (Continued)

Name(s)

Number

of Pins

Type

Description

SMBCLK

Digital Input

Serial Bus Clock.

FAN1-FAN2

5-6

Digital Inputs

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 LM81.

There is also an internal open-drain output on this line, controlled

by Bit 6 of the Configuration Register (40h) or Bit 7 CI Clear

Section 3.3 and Section 9.0.

T_CRIT_A

Digital Output

Critical Temperature Alarm active low open-drain output. This pin

can be grounded when not used.

+ (+2.8V to

+3.8V)

POWER

+3.3V V

+ power. Bypass with the parallel combination of 10 µF

(electrolytic or tantalum) and 0.1 µF (ceramic) bypass capacitors.

INT

Digital Output

Interrupt active low open-drain output. This output is enabled when

Bit 1 in the Configuration Register is set to 1. The default state is

disabled.

DACOut/NTEST_IN

Analog

Output/Digital

Input

0V to +1.25V amplitude 8-bit DAC output. When forced high by an

external voltage the NAND Tree Test mode is enabled which

provides board-level connectivity testing. Refer to Section 11.0 on

NAND Tree testing.

RESET

Digital I/O

Master Reset, 5 mA driver (open-drain), active low output with a

20 ms minimum pulse width. Available when enabled via Bit 4 in

the Configuration register. It acts as an active low power on

RESET input.

GND

GROUND

Internally connected to all circuitry. The ground reference for all

analog inputs and the DAC output. This pin needs to be

connected to a low noise analog ground plane for optimum

performance of the DAC output.

Vccp2

Analog Input

Analog input for monitoring −12V or Vccp2. Selectable by

choosing the appropriate external resistor divider values such that

the input to the LM81 is scaled to +2.5V. See

Section 4.0.

+12Vin

Analog Input

Analog input for monitoring +12V.

+5Vin

Analog Input

Analog input for monitoring +5V.

+3.3Vin

Analog Input

Analog input for monitoring +3.3V.

+2.5Vin

Analog Input

Analog input for monitoring +2.5V.

Vccp1

Analog Input

Analog input for monitoring Vccp, a processor voltage that is

nominally at +2.5V.

VID4-VID0

20-24

Digital Inputs

Supply Voltage readouts from the Pentium/PRO power supplies

that indicate the operating voltage or the processor (e.g. 1.5V to

2.9V). The values are read in the VID/Fan Divisor Register and

the VID4 Register.

TOTAL PINS

LM81 数据表(PDF) 3 Page - National Semiconductor (TI)

LM81 数据表(HTML) 3 Page - National Semiconductor (TI)

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

数据表下载

链接网址

LM81 数据表(PDF) 3 Page - National Semiconductor (TI)

LM81 数据表(HTML) 3 Page - National Semiconductor (TI)

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

数据表 下载

链接网址

数据表下载