ADT7468 View Datasheet(PDF) - ON Semiconductor

Part Name

Description

Manufacturer

ADT7468

dBCool® Remote Thermal Controller and Voltage Monitor

ON Semiconductor 

VID CODE MONITORING

The ADT7468 has five dedicated voltage ID (VID code)

inputs. These are digital inputs that can be read back through

the VID register (Reg. 0x43) to determine the processor voltage

required or being used in the system. Five VID code inputs

support VRM9.x solutions. In addition, Pin 21 (12 V input)

can be reconfigured as a sixth VID input to satisfy future

VRM requirements.

VID CODE REGISTERS

VID Code Register 0x43

<0> = VID0, reflects the logic state of Pin 5.

<1> = VID1, reflects the logic state of Pin 6.

<2> = VID2, reflects the logic state of Pin 7.

<3> = VID3, reflects the logic state of Pin 8.

<4> = VID4, reflects the logic state of Pin 19.

<5> = VID5, reconfigurable 12 V input. This bit reads 0 when

Pin 21 is configured as the 12 V input. This bit reflects the logic

state of Pin 21 when the pin is configured as VID5.

<6> THLD = 0, VID switching threshold = 1 V,

VOL < 0.8 V, VIH > 1.7 V, VMAX = 3.3 V

THLD = 1, VID switching threshold = 0.6 V,

VOL < 0.4 V, VIH > 0.8 V, VMAX = 3.3 V

<7> VIDSEL = 0, Pin 21 functions as a 12 V measurement

input. Software can read this bit to determine that there are five

VID inputs being monitored. Bit 5 of Register 0x43 (VID5)

always reads back 0. Bit 0 of Status Register 2 (Reg. 0x42)

reflects 12 V out-of-limit measurements.

VIDSEL = 1, Pin 21 functions as the sixth VID code input

(VID5). Software can read this bit to determine that there are

six VID inputs being monitored. Bit 5 of Register 0x43 reflects

the logic state of Pin 21. Bit 0 of Status Register 2 (Reg. 0x42)

reflects VID code changes.

ADT7468

VID Code Input Threshold Voltage

The switching threshold for the VID code inputs is approxi-

mately 1 V. To enable future compatibility, it is possible to

reduce the VID code input threshold to 0.6 V. Bit 6 (THLD)

of the VID register (Reg. 0x43) controls the VID input

threshold voltage.

Reconfiguring Pin 21 as VID5 Input

Pin 21 can be reconfigured as a sixth VID code input (VID5)

for VRM10-compatible systems. Because the pin is configured

as VID5, it is not possible to monitor a 12 V supply.

Bit 7 of the VID register (Reg. 0x43) determines the function of

Pin 21. System or BIOS software can read the state of Bit 7 to

determine whether the system is designed to monitor 12 V or is

monitoring a sixth VID input.

Status Register 2 (Reg. 0x42

<0> 12 V/VC = 0, if Pin 21 is configured as VID5, then Logic 0

denotes no change in VID code within the last 11 µs.

<0> 12 V/VC = 1, if Pin 21 is configured as VID5, then Logic 1

means that a change has occurred on the VID code inputs

within the last 11 µs. An SMBALERT is generated, if this

function is enabled.

VID Code Change Detect Function

The ADT7468 has a VID code change detect function. When

Pin 21 is configured as the VID5 input, VID code changes can

be detected and reported back by the ADT7468. Bit 0 of Status

Register 2 (Reg. 0x42) is the 12 V/VC bit and denotes a VID

change when set. The VID code change bit is set when the logic

states on the VID inputs are different than they were 11 µs

previously. The change of VID code can be used to generate an

SMBALERT interrupt. If an SMBALERT interrupt is not

required, Bit 0 of Interrupt Mask Register 2 (Reg. 0x75),

when set, prevents SMBALERTs from occurring on VID

code changes.

Rev. 3 | Page 15 of 81 | www.onsemi.com

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