JAJSKD7A December 2020 – May 2021 TPS92633-Q1
PRODUCTION DATA
The analog current control feature also allows to connect a NTC thermistor on ICTRL pin to achieve the LED current derating based on measured PCB board temperature or LED unit temperature. The resistance of NTC thermistor depends on the environment temperature. The resistance of NTC thermistor is decreasing with the temperature rising. It leads to the decreasing of the equivalent resistance of R(ICTRL) on ICTRL pin and the output current reduction from the calculation based on Equation 2 and Equation 3.
TI recommends to connect a resistor network including NTC thermistor (e.g. NCU18XH103F6SRB) to ICTRL pin as illustrated in below Figure 7-2. The resistor value of R1 and R2 work with NTC thermistor to adjust the equivalent resistance curve depending on the temperature to achieve the system required current derating.