FAN5235 Fairchild Semiconductor, FAN5235 Datasheet - Page 6

• Manufacturer Part Number: FAN5235
• Description: System Electronics Regulator for Mobile PCs
• Manufacturer: Fairchild Semiconductor

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