TMP139AIYAHT datasheet(11/58 Pages) TI

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2. Within time tINIT, enables the interface to accept the command from the host.

The device always powers up in the I2C mode of operation.

7.3.2 Power-Down and Device Reset

When the VDDSPD supply decreases, the device operation is not ensured below VDDSPD(min) level. To ensure that

the device operates correctly, the application must ensure that the VDDIO and VDDSPD must remain below VPOFF

for TPOFF as shown in Figure 7-3. Once the condition is met, the device shall be reset properly and the power-up

sequence will initialize the device correctly.

VDDSPD

VDDIO

VPOFF(max)

tPOFF(min)

Ready to accept I

co mmand

Figure 7-3. Power-Down and Reset Sequence

7.3.3 Temperature Result and Limits

All temperature result and limit registers are eleven bit values stored in two consecutive registers. The low byte

represented as a 11-bit signed number with the most significant bit for the temperature format being the signed

bit. Each of the temperature value bits is assigned a weight which can be used to compute the temperature

value. All unused bits read as 0 and any attempt to write a unused bit shall have no effect. The resolution of the

temperature result and limit registers is always 0.25 °C and the values can range from –255.75 °C to +255.75

°C, even though the recommended operating range is from –40 °C to +125 °C.

Table 7-1. Temperature Register Format

BYTE

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

Low Byte

0.5

0.25

RSVD = 0

High Byte

RSVD = 0

Sign

128

The Table 7-2 shows examples of the temperature register read and its corresponding conversion in °C.

Table 7-2. Temperature Register Examples

TEMPERATURE (°C)

HIGH BYTE

LOW BYTE

+255.75

0000 1111

1111 1100

+125

0000 0111

1101 0000

+95

0000 0101

1111 0000

+85

0000 0101

0101 0000

+75

0000 0100

1011 0000

0000 0000

0001 0000

+0.25

0000 0000

0000 0100

0000 0000

–0.25

0001 1111

1111 1100

–1

0001 1111

1111 0000

–25

0001 1110

0111 0000

–40

0001 1101

1000 0000

–255.75

0001 0000

0000 0000

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TMP139

SNIS217 – DECEMBER 2020

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