TMP126 datasheet(17/48 Pages) TI

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8.4.4.2 Comparator Mode

When the INT_COMP bit in the Configuration register is set to 0, the device is in comparator mode. Changing

the device to Comparator mode from Interrupt mode will immediately clear the Alert_Status register and

reset the ALERT pin. The TMP126-Q1 will then behave as described in this section at the next temperature

conversion. In this mode, the device compares the temperature result at the end of every conversion with the

limit registers. If the flag is enabled to assert the ALERT, the ALERT will reflect the status bit of the limits. For

example, if the THigh_Flag alert is enabled and the THigh_Limit is exceeded, the ALERT will assert while the

THigh_Status bit is 1. If the THigh_Flag alert is not enabled in the Alert_Enable register, the ALERT will not

assert when THigh_Status bit is 1.

After a conversion below the Hysteresis the Status bit will be set to '0' and the ALERT will de-assert. Unlike the

interrupt mode, the ALERT behavior is not affected when reading the Alert_Status register. If the Alert flag is

disabled in the Alert_Enable register, the ALERT pin will de-assert immediately if the respective bit is causing an

alert. If there are two statuses that are affecting the ALERT such as a THigh_Limit and Slew_Rate_Limit and one

of the alerts is disabled, the ALERT will remain asserted until the other limit is not exceeded. For example, if the

ALERT has asserted due to a high slew rate and a high temperature and the slew rate alert is then disabled, the

ALERT will only de-assert when the temperature drops below the hysteresis value. If both alerts were disabled

the ALERT would then de-assert.

Thus, this mode effectively makes the device behave like a high-limit threshold detector. This mode can be used

in applications where detecting if the temperature has exceeded a desired threshold is necessary. Figure 8-8

shows a timing diagram of this mode.

THigh_Limit

TLow_Limit

Temperature

Temperature conversions

THigh_Status

THigh_Flag

SPI Read

ALERT

THigh_Limit ± THigh_Hyst

TLow_Limit + TLow_Hyst

TLow_Status

TLow_Flag

Slew_Status

Slew_Rate_Limit

Slew_Flag

Figure 8-8. Comparator Mode Timing Diagram

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TMP126-Q1

SNIS227C – MAY 2021 – REVISED JUNE 2022

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TMP126 Datasheet(PDF) 17 Page - Texas Instruments