ADT7484A/ADT7486A

http://onsemi.com

7

Product Description

The ADT7484A is a single remote temperature sensor,

and the ADT7486A is a dual temperature sensor for use in

PC applications. The ADT7484A/ADT7486A accurately

measure local and remote temperature and communicate

over a one-wire Simple Serial Transport (SST) bus interface.

SST Interface

Simple Serial Transport (SST) is a one-wire serial bus and

a communications protocol between components intended

for use in personal computers, personal handheld devices, or

other industrial sensor nets. The ADT7484A/ADT7486A

support SST specification Rev 1.

SST is a licensable bus technology from Analog Devices,

Inc., and Intel Corporation. To inquire about obtaining a

copy of the Simple Serial Transport Specification or an SST

technology license, please email Analog Devices, at

sst_licensing@analog.com or write to Analog Devices,

3550 North First Street, San Jose, CA 95134, Attention: SST

Licensing, M/S B7-24.

ADT7484A/ADT7486A Client Address

The client address for the ADT7484A/ADT7486A is

selected using the address pin. The address pin is connected

to a float detection circuit, which allows the ADT7484A/

ADT7486A to distinguish between three input states: high,

low (GND), and floating. The address range for fixed

address, discoverable devices is 0x48 to 0x50.

Table 1. ADT7484A/ADT7486A Selectable Addresses

ADD1

ADD0

Address Selected

Low (GND)

Low (GND)

0x48

Low (GND)

Float

0x49

Low (GND)

High

0x4A

Float

Low (GND)

0x4B

Float

Float

0x4C

Float

High

0x4D

High

Low (GND)

0x4E

High

Float

0x4F

High

High

0x50

Command Summary

Table 7 summarizes the commands supported by the

ADT7484A/ADT7486A devices when directed at the target

address selected by the fixed address pins. It contains the

command name, command code (CC), write data length

(WL), read data length (RL), and a brief description.

Table 2. Command Code Summary

Command

Command

Code, CC

Write Length,

WL

Read Length, RL

Description

Ping()

0x00

0x00

0x00

Shows a nonzero FCS over the header if present.

GetIntTemp()

0x00

0x01

0x02

Shows the temperature of the device’s internal thermal

diode.

GetExt1Temp()

0x01

0x01

0x02

Shows the temperature of External Thermal Diode 1.

GetExt2Temp()

0x02

0x01

0x02

Shows the temperature of External Thermal Diode 2

(ADT7486A only).

GetAllTemps()

0x00

0x01

0x04 (ADT7484A)

0x06 (ADT7486A)

Shows a 4- or 6-byte block of data (ADT7484A:

GetIntTemp, GetExt1Temp; ADT7486A: GetIntTemp,

GetExt1Temp, GetExt2Temp).

SetExt1Offset()

0xe0

0x03

0x00

Sets the offset used to correct errors in External Diode 1.

GetExt1Offset()

0xe0

0x01

0x02

Shows the offset that the device is using to correct errors

in External Diode 1.

SetExt2Offset()

0xe1

0x03

0x00

Sets the offset used to correct errors in External Diode 2

(ADT7486A only).

GetExt2Offset()

0xe1

0x01

0x02

Shows the offset that the device is using to correct errors

in External Diode 2 (ADT7486A only).

ResetDevice()

0xf6

0x01

0x00

Functional reset. The ADT7484A/ADT7486A also re-

spond to this command when directed to the Target Ad-

dress 0x00.

GetDIB()

0xf7

0xf7

0x01

0x01

0x08

0x10

Shows information used by SW to identify the device’s

capabilities. Can be in 8- or 16-byte format.