A dual-edge modulation controller including first and second ramp
circuits, first and second comparators, an error amplifier and pulse
control logic. The first ramp circuit provides a leading-edge ramp
synchronous with a clock. The error amplifier compares a feedback signal
with a reference and provides a compensation signal. The first comparator
compares the leading-edge ramp with the compensation signal and asserts a
set signal. The second ramp circuit provides a trailing-edge ramp that
begins ramping when the set signal is asserted. The second comparator
compares the trailing-edge ramp with the compensation signal and asserts
a reset signal. The pulse control logic asserts a PWM signal when the set
signal is asserted and de-asserts the PWM signal when the reset signal is
asserted. The controller may control multiple phases with current
balancing. The slew rate of the ramps may be adjusted based on the number
of PWM signal asserted.