ISL6557A Datasheet, PDF (11/19 Pages) Intersil Corporation – Multi-Phase PWM Controller for Core-Voltage Regulation

ISL6557A
To enable the controller, VCC must be greater than the POR
threshold; the voltage on EN must be greater than 1.23V and
VID cannot be equal to 11111. Once these conditions are
true, the controller immediately initiates a soft start
sequence.
SOFT-START
The soft-start time, t_SS, is determined by an 11-bit counter
that increments with every pulse of the phase clock. For
example, a converter switching at 250kHz has a soft-start
time of
T_SS
=
2_----0_---4_----8_-
f_SW
=
8.2 m s
(EQ. 5)
11