TMP126 datasheet(13/45 Pages) TI

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8.4 Device Functional Modes

The TMP126 can be configured to operate in various conversion modes by using the Mode bit in the

configuration register. These modes provide flexibility to operate the device in the most power efficient way

necessary for the intended application.

8.4.1 Continuous Conversion Mode

When the Mode bit is set to 0b in the Configuration register, the device operates in continuous conversion

mode. Figure 8-4 shows that the device continuously performs temperature conversions in this mode. The

TMP126 does not wait until the end of the conversion period to update the temperature, instead the temperature

result register is updated at the end of the temperature conversion. After a completed active conversion, the

Data_Ready flag bit is set to '1'. The user can read the interrupt/status register or the temperature result register

to clear the Data_Ready flag. Therefore, the Data_Ready_Flag can be used to determine when the conversion

completes so that an external controller can synchronize reading the result register with conversion result

updates. The user can set the Data_Ready_Flag_En bit in the configuration register to monitor the state of the

Data_Ready_Flag on the ALERT pin.

Every conversion period consists of an active temperature conversion followed by a standby period. During

standby the TMP126 will de-activate all measurement circuitry to conserve power but will remain available for

any SPI communication. The device typically consumes 75 µA during the temperature conversion and only 1

µA during the low-power standby period. The duration of the temperature conversion will remain fixed, but the

conversion period can be configured using the Conv_Period[2:0] bit field in the Configuration register, allowing

the average current consumption of the device to be optimized based on the application requirements. Changing

the conversion period also affects the temperature result update rate due to the temperature result register being

updated at the end of every temperature conversion.

Use Equation 1 to calculate the average current consumption of the device in continuous conversion mode.

(1)

Active conversion time

Conversion Period

tStandby timet

Start of conversion

Temperature Conversion

Conversion Period

Figure 8-4. Conversion Period Timing Diagram

8.4.2 Shutdown Mode

When the Mode bit is set to 1b in the Configuration register, the device immediately enters the low-power

shutdown mode. If the TMP126 is making a temperature conversion, the device will stop the conversion and

discard the partial result. In this mode, the device powers down all active circuitry and can be used in conjunction

with the One_Shot bit to perform temperature conversions. Engineers can use the TMP126 for battery-operated

systems and other low-power consumption applications because the device typically only consumes 350 nA in

Shutdown Mode.

Changing between continuous and shutdown will not clear any active alerts in the Alert_Status register register

and the ALERT pin will continue to be asserted until cleared by the host. The slew rate alert will not be triggered

again in shutdown mode but will not clear until read if it is already set.

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TMP126

SNIS209 – JULY 2021

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