TMP421

TMP422

TMP423

www.ti.com

SBOS398C – JULY 2007 – REVISED MAY 2012

Table 3. Register Map

BIT DESCRIPTION

POINTER

(HEX)

POR (HEX)

7

6

5

4

3

2

1

0

REGISTER DESCRIPTION

00

00

LT11

LT10

LT9

LT8

LT7

LT6

LT5

LT4

Local Temperature (High Byte) (1)

Remote Temperature 1

01

00

RT11

RT10

RT9

RT8

RT7

RT6

RT5

RT4

(High Byte)(1)

Remote Temperature 2

02

00

RT11

RT10

RT9

RT8

RT7

RT6

RT5

RT4

(High Byte)(1) (2) (3)

Remote Temperature 3

03

00

RT11

RT10

RT9

RT8

RT7

RT6

RT5

RT4

(High Byte)(1) (3)

08

BUSY

0

0

0

0

0

0

0

Status Register

09

00

0

SD

0

0

0

RANGE

0

0

Configuration Register 1

1C/3C(2)/

0A

0

REN3(3)

REN2(2) (3)

REN

LEN

RC

0

0

Configuration Register 2

7C(3)

0B

07

0

0

0

0

0

R2

R1

R0

Conversion Rate Register

0F

X

X

X

X

X

X

X

X

One-Shot Start(4)

10

00

LT3

LT2

LT1

LT0

0

0

PVLD

0

Local Temperature (Low Byte)

11

00

RT3

RT2

RT1

RT0

0

0

PVLD

OPEN

Remote Temperature 1 (Low Byte)

Remote Temperature 2

12

00

RT3

RT2

RT1

RT0

0

0

PVLD

OPEN

(Low Byte)(2) (3)

13

00

RT3

RT2

RT1

RT0

0

0

PLVD

OPEN

Remote Temperature 3 (Low Byte)(3)

21

00

NC7

NC6

NC5

NC4

NC3

NC2

NC1

NC0

N Correction 1

22

00

NC7

NC6

NC5

NC4

NC3

NC2

NC1

NC0

N Correction 2(2) (3)

23

00

NC7

NC6

NC5

NC4

NC3

NC2

NC1

NC0

N Correction 3(3)

FC

X

X

X

X

X

X

X

X

Software Reset(5)

FE

55

0

1

0

1

0

1

0

1

Manufacturer ID

0

0

1

0

0

0

0

1

TMP421 Device ID

FF

21

0

0

1

0

0

0

1

0

TMP422 Device ID

0

0

1

0

0

0

1

1

TMP423 Device ID

(1)

Compatible with Two-Byte Read; see Figure 19.

(2)

TMP422.

(3)

TMP423.

(4)

X = undefined. Writing any value to this register initiates a one-shot start; see the One-Shot Conversion section.

(5)

X = undefined. Writing any value to this register initiates a software reset; see the Software Reset section.

The TMP421/22/23 contain circuitry to assure that a

TEMPERATURE REGISTERS

low byte register read command returns data from the

same ADC conversion as the immediately preceding

The TMP421/22/23 have multiple 8-bit registers that

high byte read command. This assurance remains

hold temperature measurement results. The local

valid only until another register is read. For proper

channel and each of the remote channels have a high

operation, the high byte of a temperature register

byte register that contains the most significant bits

should be read first. The low byte register should be

(MSBs) of the temperature analog-to-digital converter

read in the next read command. The low byte register

(ADC) result and a low byte register that contains the

may be left unread if the LSBs are not needed.

least significant bits (LSBs) of the temperature ADC

Alternatively, the temperature registers may be read

result. The local channel high byte address is 00h;

as a 16-bit register by using a single two-byte read

the local channel low byte address is 10h. The

command from address 00h for the local channel

remote channel high byte is at address 01h; the

result, or from address 01h for the remote channel

remote channel low byte address is 11h. For the

result (02h for the second remote channel result, and

TMP422, the second remote channel high byte

03h for the third remote channel). The high byte is

address is 02h; the second remote channel low byte

output first, followed by the low byte. Both bytes of

is 12h. The TMP 423 uses the same local and remote

this

read

operation

are

from

the

same

ADC

address as the TMP421 and TMP422, with the third

conversion.

The

power-on

reset

value

of

all

remote channel high byte of 03h; the third remote

temperature registers is 00h.

channel low byte is 13h. These registers are read-

only and are updated by the ADC each time a

temperature measurement is completed.

Copyright © 2007–2012, Texas Instruments Incorporated

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