MB39C308 Datasheet, PDF (8/60 Pages) Fujitsu Component Limited. – 6ch DC/DC Converter IC for LPIA Platform VR

MB39C308
CURRENT MODE TOPOLOGY
A DC/DC regulation block of Current-mode (C-mode) is illustrated in the “• DC/DC topology, Current mode
operation”.
In this C-mode, the High-side FET is turned ON while the SR-FF is set at every clock cycle generated by on
chip oscillator. During ON period (ton), the current is supplied by VIN, then Inductor current(IL) is increased.
Besides a current (IL/m), which senses the inductor current(IL), flows across a resistor (Rs) then the resister
voltage (Vs) is increased. When the Vs reaches Eout , which is an output of the Error amp, the SR-FF is reset
and the High-side FET is turned OFF (toff) until the next rising clock comes.
The voltage regulation is done by controlling a peak current of the inductor current (IL).
• DC/DC topology, Current mode operation
R1 _FB
R2
VREF
Eout
Bias
Power
Supply
SR-FF
R
Q
S
Drive
Control
Logic
OSC
Vs
High-side
Driver
CB
VIN
Bias
Low-side
Driver
Current
Sense
1
m
× IL
Rs
IL
Vo
OSC
IL
Eout
Vs
toff
ton
8
DS04-27261-6E