ZHCSIT4A September 2018 – March 2019 LM5164-Q1
PRODUCTION DATA.
The switching frequency of LM5164-Q1 is set by the on-time programming resistor placed at RON. As shown by Equation 15, a standard 100 kΩ, 1% resistor sets the switching frequency at 300 kHz.
Note that at very low duty cycles, the 50 ns minimum controllable on-time of the high-side MOSFET, tON(min), limits the maximum switching frequency. In CCM, tON(min) limits the voltage conversion step-down ratio for a given switching frequency. Calculate the minimum controllable duty cycle using Equation 16.
Ultimately, the choice of switching frequency for a given output voltage affects the available input voltage range, solution size and efficiency. The maximum supply voltage for a given tON(min) before switching frequency reduction occurs is given by Equation 17.