SE95_7

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 07 — 2 September 2009

10 of 27

NXP Semiconductors

SE95

Ultra high accuracy digital temperature sensor and thermal watchdog

When reading register Temp, all 16 bits of the two data bytes (MSByte and LSByte) must

be collected and then the two’s complement data value according to the desired resolution

must be selected for the temperature calculation. Table 8 shows the example for 11-bit

two’s complement data value, Table 9 shows the example for 13-bit two’s complement

data value.

When converting into the temperature the proper resolution must be used as listed in

Table 10 using either one of these two formulae:

1. If the Temp data MSB = 0, then: Temp (

°C) = +(Temp data) × value resolution

2. If the Temp data MSB = 1, then: Temp (

°C) = −(two’s complement Temp data) × value

resolution

Table 11 shows some examples of the results for the 11-bit calculations.

Table 8.

Example 11-bit two’s complement Temp register

MSByte

LSByte

7654321076543210

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

XXXXX

Table 9.

Example 13-bit two’s complement register

MSByte

LSByte

7654321076543210

D12 D11 D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

X

X

X

Table 10.

Temp data and Temp value resolution

Data resolution

Value resolution

8 bit

1.0

°C

9 bit

0.5

°C

10 bit

0.25

°C

11 bit

0.125

°C

12 bit

0.0625

°C

13 bit

0.03125

°C

Table 11.

Temp register value

11-bit binary

(two’s complement)

Hexadecimal value

Decimal value

Value

011 1111 1000

3F8

1016

+127.000

°C

011 1111 0111

3F7

1015

+126.875

°C

011 1111 0001

3F1

1009

+126.125

°C

011 1110 1000

3E8

1000

+125.000

°C

000 1100 1000

0C8

200

+25.000

°C

000 0000 0001

001

1

+0.125

°C

000 0000 0000

000

0

0.000

°C

111 1111 1111

7FF

−1

−0.125 °C

111 0011 1000

738

−200

−25.000 °C

110 0100 1001

649

−439

−54.875 °C

110 0100 1000

648

−440

−55.000 °C