The datasheet for the LM27761 states that the switching frequency can drop from 2 MHz if the current draw on the output is low. The datasheet states that the switching frequency could drop as low as 2 kHz if the current draw is low enough.
I'm considering this part for a sensitive analog system, so I need to ensure that the ripple frequency is sufficiently high so that it can be rejected by my signal chain.
I couldn't find any information about what the current draw amount where the switching frequency starts to drop from 2 Mhz. I expect my system to pull about 15 mA.