TMP275

SBOS363A − JUNE 2006 − REVISED JUNE 2006

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6

TEMPERATURE

(

°C)

DIGITAL OUTPUT

(BINARY)

HEX

128

0111 1111 1111

7FF

127.9375

0111 1111 1111

7FF

100

0110 0100 0000

640

80

0101 0000 0000

500

75

0100 1011 0000

4B0

50

0011 0010 0000

320

25

0001 1001 0000

190

0.25

0000 0000 0100

004

0

0000 0000 0000

000

−0.25

1111 1111 1100

FFC

−25

1110 0111 0000

E70

−55

1100 1001 0000

C90

Table 5. Temperature Data Format

The user can obtain 9, 10, 11, or 12 bits of resolution by

addressing the Configuration Register and setting the

resolution bits accordingly. For 9-, 10-, or 11-bit resolution,

the most significant bits in the Temperature Register are

used with the unused LSBs set to zero.

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

MSB first. The format of the Configuration Register for the

TMP275 is shown in Table 6, followed by a breakdown of

the register bits. The power-up/reset value of the

Configuration Register is all bits equal to 0.

BYTE

D7

D6

D5

D4

D3

D2

D1

D0

1

OS

R1

R0

F1

F0

POL

TM

SD

Table 6. Configuration Register Format

SHUTDOWN MODE (SD)

The Shutdown Mode of the TMP275 allows the user to

save maximum power by shutting down all device circuitry

other than the serial interface, which reduces current

consumption to typically less than 0.1

µA. Shutdown Mode

is enabled when the SD bit is 1; the device will shut down

once the current conversion is completed. When SD is

equal to 0, the device will maintain a continuous

conversion state.

THERMOSTAT MODE (TM)

The Thermostat Mode bit of the TMP275 indicates to the

device whether to operate in Comparator Mode (TM = 0)

or Interrupt Mode (TM = 1). For more information on

comparator and interrupt modes, see the High and Low

Limit Registers section.

POLARITY (POL)

The Polarity Bit of the TMP275 allows the user to adjust the

polarity of the ALERT pin output. If POL = 0, the ALERT pin

will be active LOW, as shown in Figure 3. For POL = 1, the

ALERT pin will be active HIGH, and the state of the ALERT

pin is inverted.

Measured

Temperature

T

HIG H

T

LO W

TMP275 ALERT PIN

(Comparator Mode)

POL = 0

TMP275 ALERT PIN

(Interrupt Mode)

POL = 0

TMP275 ALERT PIN

(Comparator Mode)

POL = 1

TMP275 ALERT PIN

(Interrupt Mode)

POL = 1

Read

Read

Time

Read

Figure 3. Output Transfer Function Diagrams

FAULT QUEUE (F1/F0)

A fault condition is defined as when the measured

temperature exceeds the user-defined limits set in the

fault conditions required to generate an alert may be

programmed using the fault queue. The fault queue is

provided to prevent a false alert as a result of

environmental

noise.

The

fault

queue

requires

consecutive fault measurements in order to trigger the

alert function. Table 7 defines the number of measured

faults that may be programmed to trigger an alert condition

order, see section High and Low Limit Registers.

F1

F0

CONSECUTIVE FAULTS

0

0

1

0

1

2

1

0

4

1

1

6

Table 7. Fault Settings of the TMP275