12

TMP104

SBOS564B – NOVEMBER 2011 – REVISED DECEMBER 2018

www.ti.com

Product Folder Links: TMP104

Submit Documentation Feedback

Copyright © 2011–2018, Texas Instruments Incorporated

Negative numbers are represented in binary twos complement format. Following power-up or reset, the

Temperature Register reads 0°C until the first conversion is complete.

(1)

The resolution for the analog-to-digital converter (ADC) is 1°C/count, where count is equal to the digital

output of the ADC.

Table 6. 8-Bit Temperature Data Format(1)

TEMPERATURE (°C)

DIGITAL OUTPUT

BINARY

HEX

128

0111 1111

7F

127

0111 1111

7F

100

0110 0100

64

80

0101 0000

50

75

0100 1011

4B

50

0011 0010

32

25

0001 1001

19

0

0000 0000

00

–1

1111 1111

FF

–25

1110 0111

E7

–55

1100 1001

C9

For positive temperatures (for example, +50°C):

Twos complement is not performed on positive numbers. Therefore, simply convert the number to binary

code, left-justified format. Denote a positive number with most significant bit (MSB) = 0.

Example: (+50°C)/(1°C/count) = 50 = 32h = 0011 0010

For negative temperatures (for example, –25°C):

Generate the twos complement of a negative number by complementing the absolute value binary number

and adding 1. Denote a negative number with MSB = 1.

Example: (|–25°C|)/(1°C/count) = 25 = 19h = 0001 1001

Twos complement format: 1110 0110 + 1 = 1110 0111

7.4.2 Configuration Register

The Configuration Register is an 8-bit read/write register used to store bits that control the operational modes of

the temperature sensor. Read/write operations are performed LSB first. The format and power-up/reset value of

the Configuration Register is shown in Table 7.

Table 7. Configuration and Power-Up/Reset Format

D7

D6

D5

D4

D3

D2

D1

D0

INT_EN

CR1

CR0

FH

FL

LC

M1

M0

0

0

0

0

0

0

1

0

7.4.2.1 Temperature Watchdog Function (FH, FL)

The TMP104 contains a watchdog function that monitors device temperature and compares the result to the

values stored in the temperature limit registers (THIGH and TLOW) in order to determine if the device temperature

is within these set limits. If the temperature of the TMP104 becomes greater than the value in the THIGH register,

then the flag-high bit (FH) in the Configuration Register is set to '1'. If the temperature falls below value in the

TLOW register, then the flag-low bit (FL) is set to '1'. If both flag bits remain '0', then the temperature is within the

temperature window set by the temperature limit registers, as shown in Figure 13.