An improved circuit and method for increasing the stability of switch-mode
power supplies via frequency fold-back is disclosed. For example, a
circuit for increasing the stability of a switch-mode power supply using
the compensation signal to control the frequency of the oscillator is
disclosed, which includes an operational amplifier that functions to
scale the compensation signal. Thus, the switching frequency of the power
supply involved is decreased as the load is reduced. This novel use of
the compensation signal to control the switching frequency of a
switch-mode power supply significantly increases the stability of the
power supply as compared to prior switch-mode power supplies. Therefore,
the switch-mode power supply may be used for those applications where
relatively high stability is desired.