Are you sure it's not compensated incorrectly?
Pulse skipping is, well, skipping pulses, but that's a burst waveform. Some controllers still do that, but I don't know if that's typical for this one.
Tim
You are right the terminology is confusing, its more of burst/sleep mode. TI seems to like to call it that:
The converter operates with a fixed frequency PWM control topology and, if power-save mode is enabled, it uses a pulse-skipping mode at light-load currents.
I've tried with Cn, compensation cap removed, no major difference seen there.
With Cf-, feedforward capacitor removed, duty cycle of the pulses increases to ~%50, ripple reduces significantly, and power consumption goes up a bit. So thats on the right path. But removing it is too risky.
Note here about >33uF not recommended, but I'm getting same issue with lower values:
https://e2e.ti.com/support/power-management/f/196/t/799796Also there, at a point below ~80mA on the Vneg, discontinuous conduction occurs.
When testing today I found dropping Vin from 5V to ~4.2V would kick it out of power-save mode and into normal PWM. It would also get into some wild states above 5.3V. Might need to play with that a bit more..