SLVSAH5E December 2010 – May 2019 TPS57114-Q1
The switching frequency of the TPS57114-Q1 device is adjustable over a wide range from 300 kHz to 2000 kHz by placing a resistor on the RT/CLK pin with a value calculated by Equation 8. An internal amplifier holds this pin at a fixed voltage when using an external resistor to ground to set the switching frequency. RT/CLK is typically 0.5 V. To determine the timing resistance for a given switching frequency, use the curve in Figure 5 or Equation 8.
To reduce the solution size, one would typically set the switching frequency as high as possible, but consider tradeoffs of the efficiency, maximum input voltage, and minimum controllable on-time.
The minimum controllable on-time is typically 65 ns at full-current load and 120 ns at no load, and limits the maximum operating input voltage or output voltage.