LM87 datasheet(28/32 Pages) NSC

28 / 32 page

Functional Description (Continued)

Bit

Name

Read/Write

Description

4-5

FAN1 RPM

Control

Read/Write

FAN1 Speed Control.

<5:4> = 00 - divide by 1;

<5:4> = 01 - divide by 2;

<5:4> = 10 - divide by 4;

<5:4> = 11 - divide by 8.

6-7

FAN2 RPM

Control

Read/Write

FAN2 Speed Control.

<7:6> = 00 - divide by 1;

<7:6> = 01 - divide by 2;

<7:6> = 10 - divide by 4;

<7:6> = 11 - divide by 8.

13.13 VID4 Register — Address 49h

Power on default – <7:1> = 100 000, <0> = VID4.

Bit

Name

Read/Write

Description

VID4

Read Only

Bit 4 of VID data from the CPU or power supply that indicates the operating voltage

(e.g. 1.5 V to 2.9 V).

1-7

Reserved

Read/Write

13.14 Configuration Register 2 — Address 4Ah

Power on default – <7:0> = 0000 0000 binary

Bit

Name

Read/Write

Description

Thermal INT#

Mask

Read/Write

When this bit is set to 1, thermal error events will not affect the INT# interrupt

output. THERM# outputs will still function normally.

Local Temp.

Once Bit

Read/Write

Once

When set to 1, this bit locks in the value set in the Internal Temp. high limit register

at 0x13h. The value cannot be changed until a power on reset is performed, or the

chip is re-Initialized by writinga1toBit7of Configuration Register 1 (Register

40h).

Remote Temp.

Once Bit

Read/Write

Once

When set to 1, this bit locks in the value set in the External Temp. high limit

performed, or the chip is re-Initialized by writinga1toBit7of Configuration

THERM# Interrupt

Mode

Read/Write

When set to 0, the THERM# output functions in Default mode. When set to 1, the

THERM# output functions in ACPI mode.

4-5

Reserved

IRQ3 Enable

Read/Write

When set to 1, VID3/IRQ3 is enabled as an active high interrupt input (if the

IRQEN bit is set in bit 7 of the Channel Mode Register).

IRQ4 Enable

Read/Write

When set to 1, VID4/IRQ4 is enabled as an active high interrupt input (if the

IRQEN bit is set in bit 7 of the Channel Mode Register).

13.15 Interrupt Status Register 1 Mirror — Address 4Ch

Power on default – <7:0> = 0000 0000 binary

Bit

Name

Read Only

Description

+2.5Vin

Read Only