Below is the LTspice simulation of a simple hysteretic converter:
It uses an LM339/393 comparator, and six CD4050 buffers (one package) to act as a driver for the large gate capacitance of the P-MOSFET.
(A MOSFET gate driver IC can be used in place of the CD4050).
A TL431 programmable 2.5V reference is used to set the output voltage at 5V.
C3 provides a slow (soft) start to minimize any output voltage overshoot during startup (otherwise the output would go to about 10V).
It has about 70mVpp ripple with a 10A load, which should be acceptable for most digital circuit requirements.
Note that the inductor must be able to handle at least 10A without saturating.
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