SNVSBN6 April 2020 LM5181-Q1
The LM5181-Q1 employs a unique thermal compensation circuit that adjusts the feedback setpoint based on the thermal coefficient of the forward voltage drop of the flyback diode. Even though the output voltage is measured when the secondary current is effectively zero, there is still a non-zero forward voltage drop associated with the flyback diode. Select the thermal compensation resistor using Equation 9.
The temperature coefficient of the diode voltage drop may not be explicitly provided in the diode data sheet, so the effective value can be estimated based on the measured output voltage shift overtemperature when the TC resistor is not installed.