ADT7482

Rev. 0 | Page 12 of 24

REGISTERS

The registers in the ADT7482 are 8-bits wide. These registers

are used to store the results of remote and local temperature

measurements and high and low temperature limits and to

configure and control the device. A description of these registers

follows.

ADDRESS POINTER REGISTER

The address pointer register itself does not have, or require, an

address, as the first byte of every write operation is automatically

written to this register. The data in this first byte always contains

the address of another register on the ADT7482, which is stored

in the address pointer register. It is to this register address that

the second byte of a write operation is written to or to which a

subsequent read operation is performed.

The power-on default value of the address pointer register is

0x00. Therefore, if a read operation is performed immediately

after power-on, without first writing to the address pointer, the

value of the local temperature is returned, since its register

address is 0x00.

CONFIGURATION REGISTERS

There are two configuration registers used to control the

operation of the ADT7482. Configuration 1 register is at

Address 0x03 for reads and Address 0x09 for writes. See Table 9

for details regarding the operation of this register. Configuration 2

Register is at Address 0x24 for both reads and writes. Setting Bit

7 of this register locks all lockable registers. The affected

registers can only be modified if the ADT7482 is powered down

and powered up again. See Table 16 for a list of the registers

affected by the lock bit.

TEMPERATURE VALUE REGISTERS

The ADT7482 has five registers to store the results of local and

remote temperature measurements. These registers can only be

written to by the ADC and can be read over the SMBus.

•

The local temperature value register is at Address 0x00.

•

The Remote 1 temperature value high byte register is at

Address 0x01; the Remote 1 low byte register is at

Address 0x10.

•

The Remote 2 temperature value high byte register is at

Address 0x30; the Remote 2 low byte register is at

Address 0x33.

•

The Remote 2 temperature values can be read from

Addresses 0x01 for the high byte and Address 0x10 for the

low byte if Bit 3 of Configuration Register 1 is set to 1.

•

To read the Remote 1 temperature values, set Bit 3 of

Configuration Register 1 to 0.

•

The power-on default for all five registers is 0x00.

Table 9. Configuration 1 Register (Read Address = 0x03, Write Address = 0x09)

Bit

Mnemonic

Description

7

Mask

Setting this bit to 1 masks all ALERTs on the ALERT pin. Default = 0 = ALERT enabled. This applies only if Pin 8 is

configured as ALERT, otherwise it has no effect.

6

Mon/STBY

Setting this bit to 1 places the ADT7482 in standby mode (that is, it suspends all temperature measurements (ADC). The

SMBus remains active and values can be written to and read from the registers. THERM and ALERT are also active in

standby mode. Changes made to the limit registers in standby mode that effect the THERM or ALERT outputs cause

these signals to be updated. Default = 0 = temperature monitoring enabled.

5

AL/TH

This bit selects the function of Pin 8. Default = 0 = ALERT. Setting this bit to 1 configures Pin 8 as THERM2 pin.

4

Reserved

Reserved for future use.

3

Remote 1

/Remote 2

Setting this bit to 1 enables Remote 2 values to be read from the Remote 1 registers. Default = 0 = Remote 1

temperature values and limits are read from these registers.

2

Temp

Range

Setting this bit to 1 enables the extended temperature measurement range (−50°C to +150°C).

Default = 0 = (0°C to +127°C).

1

Mask R1

Setting this bit to 1 masks ALERTs due to the Remote 1 temperature exceeding a programmed limit. Default = 0.

0

Mask R2

Setting this bit to 1 masks ALERTs due to the Remote 2 temperature exceeding a programmed limit. Default = 0.

Table 10. Configuration 2 Register (Read/Write Address = 0x24)

Bit

Mnemonic

Description

7

Lock Bit

Setting this bit to 1 locks all lockable registers to their current values. This prevents settings from being tampered with

until the device is powered down. Default = 0.

<6:0>

Res

Reserved for future use.