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TMP61

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SBOS921 – DECEMBER 2018

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Typical Application (continued)

(7)

Figure 17. TMP61 Thermal Compensation Circuit

9.2.1.2.2

Thermal Protection With Comparator

Thermal protection can be programmed using the TMP61, a voltage reference, and a comparator. As shown in

overtemperature warning signal. Hysteresis can also be useful to program when the output will return low, so that

the output does not continuously toggle around the threshold. Either a comparator with built-in hysteresis or

feedback resistors may be used.

Figure 18. Temperature Switch Using TMP61 Voltage Divider and a Comparator

9.2.1.2.3

Thermal Foldback

One application that uses the output voltage of the TMP61 in active control circuit is thermal foldback. This is

performed to reduce, or fold back, the current driving a string of LEDs, for example. At high temperatures, the

LEDs begin to heat up due to environmental conditions and self-heating. Thus, at a certain temperature threshold

based on the LED's safe operating area, the driving current must be reduced to cool down the LEDs and prevent

thermal runaway. The TMP61 voltage output increases with temperature, when it is in the lower position of the

voltage divider, and provides a response that can be used to fold back the current. Typically, the current is held

at a specified level until a high temperature is reached, known as the knee point, where the current must be