REV. A

ADM1028

–14–

Table V. Register 0x40 Configuration Register Power-On Default <7:0> = 21h

Bit

Name

R/

W

Description

0

START

Read/Write

Setting this bit to a “1” enables startup of ADM1028; clearing this bit to “0”

places ADM1028 in standby mode. At startup, temperature monitoring and

limit checking functions begin. Note, all limit values should be programmed

into ADM1028 prior to using the standard thermal interrupt mechanism

based upon high and low limits. (Power-Up Default = 1.)

1

INT Enable

Read/Write

Setting this bit to a “1” enables the

INT output. 1 = Enabled 0 = Disabled

(Power-Up Default = 0.)

2

Reserved

Read Only

Reserved (Default = 0).

3

Programmable

Read/Write Once

Setting this bit to a “1” will lock in the value set into the Programmable Remote

Therm Limit

Therm Limit Register (Value Register 0x14). Furthermore, if this bit is set,

Lock Bit

the values in the Default Remote Therm Limit Register Bit (Value Register

0x18) will no longer have an effect on the

THERM, FAN_SPD, or FAN_OFF

outputs. This bit cannot be written again until after RST has been asserted.

(Power-Up Default = 0.)

4

Soft Reset

Read/Write

Setting this bit to a “1” will restore power-up default values to the Configu-

ration Register, Interrupt Status Register and Interrupt Mask Register. This

also rearms

INT structure but not the THERM structure. This bit automati-

cally clears itself since the power-on default is zero.

5

FAN_OFF

Read/Write

Setting this bit to a “1” will cause the

FAN_OFF pin to be floated. Clearing

this bit to “0” will cause the

FAN_OFF pin to be driven low which requests

that the fan be turned off. This bit will be unconditionally set if the

THERM

pin is ever asserted; once

THERM is negated this bit must be returned to its

prior state (prior to

THERM assertion). Reading this bit reflects the state of

the

FAN_OFF output buffer. Due to the open-drain nature of this pin the

value read does not represent the actual state of the external circuit con-

nected to it. (Power-Up Default = 1.)

6

GPI Invert

Read/Write

Setting this bit to a “1” will invert the GPI input for the purpose of level

detection and interrupt generation. Clearing this bit to “0” leaves the GPI

input unmodified. (Power-Up Default = 0.)

7

Reserved

Read Only

Reserved. (Power-Up Default = 0).

Table VI. Register 0x41. Interrupt Status Register. Power-On Default <7:0> = 00h

Bit

Name

Read/Write

Description

0

Int. Temp Error

Read/Write

A one indicates that one of the limits for the internal temperature sensor

“1” to clear

has been exceeded.

1

Flag 1

Read/Write

This bit can be used as a general purpose flag with the capability of generat-

ing an interrupt. Writing a “1” to this bit causes it to be set to “1.” Writing a

“0” clears this bit.

2

Flag 2

Read/Write

This bit can be used as a general purpose flag with the capability of generat-

ing an interrupt. Writing a “1” to this bit causes it to be set to “1.” Writing a

“0” clears this bit.

3

Int.

THERM

Read/Write

A one indicates that the internal thermal overload (

THERM) limit has

“1” to clear

been exceeded.

4

GPI Input

Read Only

A “1” indicates that the GPI pin is asserted. The polarity of the GPI pin is

determined by GPI Invert (Bit 6) in the Configuration Register. For ex-

ample, if GPI Invert is cleared then this bit will be “1” when the GPI pin is

high (“1”); this bit will be “0” when the GPI pin is low (“0”.) If GPI Invert

is set then this bit will be “1” when the GPI pin is low (“0”); this bit will be

“0” when the GPI pin is high (“1”). Note that the state of GPI is not latched;

this bit simply reflects the state or inverted state of the GPI pin. Note: if this

bit is “1” reading this register will NOT clear it to “0.”

5

Ext. Temp Error

Read/Write

A one indicates that one of the limits for the external temperature sensor

“1” to clear

has been exceeded.

6

Ext.

THERM

Read/Write

A one indicates that the external thermal overload (

THERM) limit has

“1” to clear

been exceeded.

7

Ext Diode Fault

Read/Write

A one indicates either a short- or open-circuit fault on the remote sensor diode.

“1” to clear