TMP122, TMP124

5

SBOS272B

www.ti.com

APPLICATIONS INFORMATION

The TMP122 and TMP124 digital temperature sensors are

optimal for thermal management and thermal protection appli-

cations. The TMP122/TMP124 are SPI interface-compatible

and specified for a temperature range of –40

°C to +125°C.

The TMP122/TMP124 require minimal external components

for operation, needing only a pull-up resistor on the ALERT

pin and a bypass capacitor on the supply. Bypass capacitors

of 0.1

µF is recommended. Figure 1 shows typical connec-

tions for the TMP122 and TMP124.

FIGURE 1. Typical Connections of the TMP122 and TMP124.

COMMUNICATING WITH THE TMP122

low during a conversion the conversion process continues, but

the last completed conversion is available at the output regis-

ter. Communication with the TMP122/TMP124 is initiated by

temperature data from the temperature sensors. The 16-bit

data word is clocked out sign bit first, followed by the MSB. Any

transfer in a READ or WRITE command. READ and WRITE

commands are described in Tables I and II.

The READ command contains an embedded address in bits

D4 and D3 to identify which register to read. Bits D4 and D3

are internally registered and will hold their value following a

READ command until a entire 16-bit read is completed by the

user. The completion of the 16-bit READ acknowledges that

the READ command has been completed. If the user issues

subsequent clocks, the data from that register will be available

remain in effect until a full 16 clocks have been received. After

the completion of a 16-bit READ from the part, the READ

address is reset to return data from the Temperature Register.

A WRITE command to a register will not change the READ

address registered. For further discussion on the READ ad-

dress register, see the

Read Address Register section.

Multiple commands may be strung together as illustrated in

Figure 2. The TMP122/TMP124 accepts commands alternat-

always responds with a READ from the address location

indicated by the READ address register. If the next com-

mand is a READ command then data is returned from the

address specified by the READ command with the 16th clock

resetting the READ address register to the default tempera-

ture register. The TMP122/TMP124 then expect a 16-bit

command. If the command is a WRITE command, then the

16 clocks following the command will again return tempera-

ture data.

Figures 3, 4, 5, and 6 detail the communication sequences.

TMP122

0.1

µF

V+

GND

2

5

1

3

CS

NOTE: Alert requires

pull-up resistor (open drain).

NC indicates pin should be left

open or floating.

ALERT

(Output)

4

6

SCK

SO/I

TMP124

0.1

µF

V+

GND

4

5

7

8

ALERT

(Output)

6

NC

CS

NC

SCK

SO/I

3

1

2

To maintain accuracy in applications requiring air or surface

temperature measurement, care should be taken to isolate

the package and leads from ambient air temperature.

Read Command

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

Temperature

1000000

0

0

00

0

0

000

Configuration Register

1000000

0

0

00

0

1

000

Low Temp Threshold

1000000

0

0

00

1

0

000

High Temp Threshold

1000000

0

0

00

1

1

000

TABLE I. Read Command.

Write Command

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

Configuration Register

0000

D1

D0

R1

R0

F1

F0

POL

TM1

TM0

0

1

0

Low Temp Threshold

T12

T11

T10

T9

T8

T7

T6

T5

T4

T3

T2

T1

T0

1

0

0

High Temp Threshold

T12

T11

T10

T9

T8

T7

T6

T5

T4

T3

T2

T1

T0

1

1

0

Shutdown Command

xxxxxxxx

1111

1

1

1

1

TABLE II. Write Command.

16-Bit

READ

CS

SO/I

16-Bit

READ

COMMAND

16-Bit

Response

16-Bit

WRITE/

Embedded

Address

16-Bit

READ

FIGURE 2.Multiple Command Sequence.