7.3.10 Constant Switching Frequency and Timing Resistor (RT/CLK Pin)

The switching frequency of the TPS57060-Q1 device is adjustable over a wide range from approximately 100 kHz to 2500 kHz by placing a resistor on the RT/CLK pin. The RT/CLK pin voltage is typically 0.5 V and must have a resistor to ground to set the switching frequency. To determine the timing resistance for a given switching frequency, use Equation 7 or the curves in Figure 31 or Figure 32. To reduce the solution size, set the switching frequency as high as possible, but tradeoffs of the supply efficiency, maximum input voltage and minimum controllable on time should be considered.

The minimum controllable on time is typically 130 ns and limits the maximum operating input voltage.

The maximum switching frequency is also limited by the frequency shift circuit. Use Equation 7 or the curves in Figure 31 or Figure 32 to calculate the timing resistor values for the required switching frequency.

Equation 7.

Figure 31. High Range RT

Figure 32. Low Range RT