SLVSCG7A July 2014 – September 2021 TPS55340-EP
PRODUCTION DATA
The switching frequency is set by a resistor (RFREQ) connected to the FREQ pin of the TPS55340-EP. The relationship between the timing resistance RFREQ and frequency is shown in Figure 7-5. Do not leave this pin open. A resistor must always be connected from the FREQ pin to ground for proper operation. Calculate the resistor value required for a desired frequency using Equation 1.
For the given resistor value, calculate the corresponding frequency with Equation 2.
The TPS55340-EP switching frequency can be synchronized to an external clock signal that is applied to the SYNC pin. The required logic levels of the external clock are shown in the specification table. The recommended duty cycle of the clock is in the range of 10% to 90%. A resistor must be connected from the FREQ pin to ground when the converter is synchronized to the external clock and the external clock frequency must be within ±20% of the corresponding frequency set by the resistor. For example, if the frequency programmed by the FREQ pin resistor is 600 kHz, the external clock signal should be in the range of 480 to 720 kHz.