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TMP421-Q1, TMP422-Q1, TMP423-Q1

SBOS821 – NOVEMBER 2016

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

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Copyright © 2016, Texas Instruments Incorporated

(1)

Resolution is 1°C/count. Negative numbers are represented in 2s-complement format.

(2)

Resolution is 1°C/count. All values are unsigned with a –64°C offset.

8.3 Feature Description

8.3.1 Temperature Measurement Data

Temperature measurement data can be taken over an operating range of –40°C to +127°C for both local and

remote locations.

However, measurements from –55°C to +150°C can be made both locally and remotely by reconfiguring the

TMP421-Q1, TMP422-Q1, and TMP423-Q1 for the extended temperature range, as described as follows.

Temperature data that result from conversions within the default measurement range are represented in binary

form, as shown in Table 1, 2s Complement Standard Binary column. Note that although the device is rated to

only measure temperatures down to –55°C, the device can read temperatures below this level. However, any

temperature below –64°C results in a data value of –64 (C0h). Likewise, temperatures above 127°C result in a

value of 127 (7Fh). The device can be set to measure over an extended temperature range by changing bit 2

(RANGE) of Configuration Register 1 from low to high. The change in measurement range and data format from

standard binary to extended binary occurs at the next temperature conversion. For data captured in the extended

temperature range configuration, an offset of 64 (40h) is added to the standard binary value, as shown in the

Extended Binary column of Table 1. This configuration allows measurement of temperatures as low as –64°C,

and as high as 191°C; however, most temperature-sensing diodes only measure with the range of –55°C to

+150°C. Additionally, the TMP421-Q1, TMP422-Q1, and TMP423-Q1 are rated only for ambient temperatures

ranging from –40°C to +125°C. Parameters in the Absolute Maximum Ratings table must be observed.

Table 1. Temperature Data Format (Local and Remote Temperature High Bytes)

TEMPERATURE

(°C)

LOCAL/REMOTE TEMPERATURE REGISTER

HIGH BYTE VALUE (1°C RESOLUTION)

2s COMPLEMENT STANDARD BINARY(1)

EXTENDED BINARY(2)

BINARY

HEX

BINARY

HEX

–64

1100 0000

C0

0000 0000

00

–50

1100 1110

CE

0000 1110

0E

–25

1110 0111

E7

0010 0111

27

0

0000 0000

00

0100 0000

40

1

0000 0001

01

0100 0001

41

5

0000 0101

05

0100 0101

45

10

0000 1010

0A

0100 1010

4A

25

0001 1001

19

0101 1001

59

50

0011 0010

32

0111 0010

72

75

0100 1011

4B

1000 1011

8B

100

0110 0100

64

1010 0100

A4

125

0111 1101

7D

1011 1101

BD

127

0111 1111

7F

1011 1111

BF

150

0111 1111

7F

1101 0110

D6

175

0111 1111

7F

1110 1111

EF

191

0111 1111

7F

1111 1111

FF