ADT7476ARQH 查看數據表（PDF） - ON Semiconductor

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ADT7476ARQH

dBCOOL® Remote Thermal Controller and Voltage Monitor

ON Semiconductor 

ADT7476

VID Code Monitoring

The ADT7476 has five dedicated voltage ID (VID code)

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

the VID/GPIO register (0x43) to determine the processor

voltage required or the system being used. 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/GPIO Register (0x43)

[0] = VID0, reflects logic state of Pin 5.

[1] = VID1, reflects logic state of Pin 6.

[2] = VID2, reflects logic state of Pin 7.

[3] = VID3, reflects logic state of Pin 8.

[4] = VID4, reflects 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.

VID Code Input Threshold Voltage

The switching threshold for the VID code inputs is

approximately 1.0 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/GPIO register (0x43) controls the

VID input threshold voltage.

VID/GPIO Register (0x43)

[6] THLD = 0, VID switching threshold = 1.0 V,

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

[6] THLD = 1, VID switching threshold = 0.6 V,

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

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/GPIO register (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 a sixth VID input.

VID/GPIO Register (0x43)

[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 VID/GPIO

Register (0x43) always reads back 0. Bit 0 of Interrupt Status

Register 2 (0x42) reflects 12 V out−of−limit measurements.

[7] 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 Interrupt

Status Register 2 (0x42) reflects VID code changes.

VID Code Change Detect Function

The ADT7476 has a VID code change detect function.

When Pin 21 is configured as the VID5 input, VID code

changes are detected and reported back by the ADT7476. Bit

0 of Interrupt Status Register 2 (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 ms previously. The change of VID code is used

to generate an SMBALERT interrupt. If an SMBALERT

interrupt is not required, Bit 0 of Interrupt Mask Register 2

(0x75), when set, prevents SMBALERTs from occurring on

VID code changes.

Interrupt Status Register 2 (0x42)

[0] 12 V/VC = 0, if Pin 21 is configured as VID5, Logic 0

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

[0] 12 V/VC = 1, if Pin 21 is configured as VID5, Logic 1

means that a change has occurred on the VID code inputs

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

function is enabled.

Programming the GPIOs

The ADT7476 follows an upgrade path from the ADM1027

to the ADT7476. In order to maintain consistency between

versions, it is necessary to omit references to GPIO5. As a

result, there are six GPIOs as follows: GPIO0, GPIO1, GPIO2,

GPIO3, GPIO4, and GPIO6.

Setting Bit 4 of Configuration Register 5 (0x7C) to 1

enables GPIO functionality. This turns all pins configured as

VID inputs into general−purpose outputs. Writing to the

corresponding VID bit in the VID/GPIO register (0x43) sets

the polarity for the corresponding GPIO. GPIO6 can be

programmed independently as, for example, an input or

output, using Bits [3:2] of Configuration Register 5 (0x7C).

Temperature Measurement Method

Local Temperature Measurement

The ADT7476 contains an on−chip band gap temperature

sensor whose output is digitized by the on−chip, 10−bit

ADC. The 8−bit MSB temperature data is stored in the

temperature registers (Addresses 0x25, 0x26, and 0x27).

Because both positive and negative temperatures can be

measured, the temperature data is stored in Offset 64 format

or twos complement format, as shown in Table 6 and

Table 7. Theoretically, the temperature sensor and ADC can

measure temperatures from −63°C to +127°C (or −61°C to

+191°C in the extended temperature range) with a resolution

of 0.25°C. However, this exceeds the operating temperature

range of the device, so local temperature measurements

outside the ADT7476 operating temperature range are not

possible.

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