ADT7408

Rev. 0 | Page 10 of 24

REGISTERS

The ADT7408 contains 16 accessible registers, shown in Table 5.

The address pointer register is the only register that is eight bits;

the other registers are 16 bits wide. On power-up, the address

pointer register is loaded with 0x00 and points to the capability

register.

Table 5. Registers

Pointer

Address

Name

Power-On

Default

Read/Write

Not

Applicable

Address Pointer

Register

0x00

Write

0x00

Capability Register

0x001D

Read

0x01

Configuration Register

0x0000

Read/Write

0x02

Alarm Temperature

Upper Boundary

Trip Register

0x0000

Read/Write

0x03

Alarm Temperature

Lower Boundary

Trip Register

0x0000

Read/Write

0x04

Critical Temperature

Trip Register

0x0000

Read/Write

0x05

Temperature Value

Register

Undefined

Read

0x06

Manufacturer ID

Register

0x11D4

Read

0x07

Device ID/Revision

Register

0x080X

Read

0x08 to 0x0F

Vendor-Defined

Registers

0x0000

Reserved

ADDRESS POINTER REGISTER (WRITE ONLY)

This 8-bit write only register selects which of the 16-bit registers

is accessed in subsequent read/write operations. Address space

between 0x08 and 0x0F is reserved for factory usage.

MSB

LSB

D7

D6

D5

D4

D3

D2

D1

D0

0

0

0

0

Register

select

Register

select

Register

select

Register

select

Table 6. Address Pointer Selected Registers

D2

D1

D0

Register Selected

0

0

0

Capability Register

0

0

1

Configuration Register

0

1

0

Alarm Temperature Upper Boundary Trip

Register

0

1

1

Alarm Temperature Lower Boundary Trip

Register

1

0

0

Critical Temperature Trip Register

1

0

1

Temperature Value Register

1

1

0

Manufacturer ID Register

1

1

1

Device ID/Revision Register

CAPABILITY REGISTER (READ ONLY)

This 16-bit, read-only register indicates the capabilities of the

thermal sensor, as shown in Table 7 and the following bit map.

Note that RFU means reserved for future use.

MSB

LSB

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

RFU

RFU

RFU

RFU

RFU

RFU

RFU

RFU

RFU

RFU

RFU

TRES1

TRES0

Wider

range

Higher

precision

Alarm/Critical

trips

Table 7. Capability Mode Description

Bit

Function

Basic capability

D0

Trips Capability

D0

Alarm/Critical Trips

1

Alarm and critical trips capability

Accuracy

D1

Accuracy Capability

D1

Higher Precision

0

Default accuracy ±2°C over the active range and ±3°C over the monitor range

Wider range

D2

Temperature Range Capability

D2

Wider Range

1

Can read temperature below 0°C and set sign bit accordingly (default)

Temperature resolution

[D4:D3]

Temperature Resolution

01

0.25°C LSB

[D4:D3]

Temperature Resolution

11

0.0625°C LSB (default)

[D15:D5]

Reserved for future use; must be 0