JAJSF96C April 2018 – October 2021 LM5036
PRODUCTION DATA
The on-time for the auxiliary supply is determined by the resistor RON, and is inversely proportional to the input voltage, resulting in a nearly constant switching frequency as the input voltage is varied over its entire range. Figure 7-23 shows the block diagram for the on-time generator.
A current source, which is a function of the input voltage and the RON resistor value, charges a capacitor. The capacitor voltage ramps up linearly and gets reset when it reaches the threshold.
Use Equation 32 to calculate the on time tON of the high-side switch.