One-ShotStartRegister

ConfigurationRegisters

StatusRegister

IdentificationRegisters

N-FactorCorrectionRegisters

ConversionRateRegister

LocalandRemoteTemperatureRegisters

SDA

SCL

PointerRegister

I/O

Control

Interface

SoftwareReset

21

TMP421-Q1, TMP422-Q1, TMP423-Q1

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SBOS821 – NOVEMBER 2016

Product Folder Links: TMP421-Q1 TMP422-Q1 TMP423-Q1

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Copyright © 2016, Texas Instruments Incorporated

(1)

Compatible with Two-Byte Read; see Figure 17.

(2)

TMP422-Q1.

(3)

TMP423-Q1.

(4)

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

8.6 Register Maps

The TMP421-Q1, TMP422-Q1, and TMP423-Q1 contain multiple registers for holding configuration information,

temperature measurement results, and status information. These registers are described in Figure 19 and

Table 6.

8.6.1 Pointer Register

Figure 19 shows the internal register structure of the TMP421-Q1, TMP422-Q1, and TMP423-Q1. The 8-bit

Pointer Register is used to address a given data register. The Pointer Register identifies which of the data

registers must respond to a read or write command on the two-wire bus. This register is set with every write

command. A write command must be issued to set the proper value in the Pointer Register before executing a

read command. Table 6 describes the pointer address of the TMP421-Q1, TMP422-Q1, and TMP423-Q1

registers. The power-on reset (POR) value of the Pointer Register is 00h (0000 0000b).

Figure 19. Internal Register Structure

Table 6. Register Map

POINTER

(HEX)

POR (HEX)

BIT DESCRIPTION

REGISTER DESCRIPTION

7

6

5

4

3

2

1

0

00

00

LT11

LT10

LT9

LT8

LT7

LT6

LT5

LT4

Local Temperature (High Byte)(1)

01

00

RT11

RT10

RT9

RT8

RT7

RT6

RT5

RT4

Remote Temperature 1

(High Byte)(1)

02

00

RT11

RT10

RT9

RT8

RT7

RT6

RT5

RT4

Remote Temperature 2

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

03

00

RT11

RT10

RT9

RT8

RT7

RT6

RT5

RT4

Remote Temperature 3

(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

0A

1C/3C(2)/

7C(3)

0

REN3(3)

REN2(2) (3)

REN

LEN

RC

0

0

Configuration Register 2

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)

12

00

RT3

RT2

RT1

RT0

0

0

PVLD

OPEN

Remote Temperature 2

(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)