FAN5235 Datasheet, PDF (6/15 Pages) Fairchild Semiconductor – System Electronics Regulator for Mobile PCs

FAN5235
CLK
HI
GATE
LOGIC
PWM
LO
ADAPTIVE GATE
CONTROL
VCC
VFB
ISEN
VREF
LSD
ERROR AMP
REF
DUTY
CYCLE
CLAMP
LSD
OC DETECT
VCC
SET
QD
CLK
Q _CLR L
PWM LATCH
SUM
PWM
RAMP
CURRENT SENSE
AMP
FAN5235
5V/3.3V Switcher
5V
VIN
CPUMP
HSD
PHASE
ISEN
LSD
VFB
L1
VOUT
CL
PGND
Figure 1. FAN5235 5V/3.3V Internal Block Diagram of PWM Loop
Vout
VFB12
6
CK :3
CK :3
V_e
Ramp
PWM
VREF=2.5V
R
Ramp
16R
–
+
V_e
FAN5235
12V Converter
CLK:3
(30%DC, 100kHz)
S
+
–
PWM
R
CLK:3
Q
Q
DISABLE
Figure 2. FAN5235 12V Internal Block Diagram
+5
SW12
V _out
REV. 1.3.3 1/3/02