ZHCSN09A June 2021 – September 2022 LM5168-Q1 , LM5169-Q1
PRODUCTION DATA
The on time of the LM516x-Q1 high-side FET is determined by the RT resistor and is inversely proportional to the input voltage, VIN. The inverse relationship with VIN results in a nearly constant frequency as VIN is varied. Use Equation 1 to calculate the on time, where RT is in kΩ.
Use Equation 2 to determine the RT resistor to set a specific switching frequency in CCM, where FSW is in kHz.
Select RT for a minimum on time (at maximum VIN) greater than 50 ns for proper buck operation and greater than 100 ns for proper fly-buck converter operation. In addition to this minimum on time, the maximum frequency for this device is limited to 1 MHz.