Data Sheet

© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN7621 • Rev. 1.0.3 2
FAN7621 — PFM Controller for Half-Bridge Resonant Converters
Application Circuit Diagram
R
sense
FAN7621
C
DL
V
CC
LVcc
RT
CON
CS
SG PG
CTR
HV
CC
Cr
L
lk
Lm
Ns
V
O
D1
D2
R
F
C
F
Np
Ns
KA431
V
IN
HO
LO
Figure 1. Typical Application Circuit (LLC Resonant Half-Bridge Converter)
Block Diagram
OLP
TSD
LV
CC
good
Low-Side
Gate Drive
High-Side
Gate Drive
6
1
12
11.3 / 14.5V
V
REF
Internal
Bias
LV
CC
good
3
HO
CS
CON
LV
CC
HV
CC
CTR
R
T
V AOCP
PG
LV
CC
OVP
Time
Delay
2
8
16
9
Time
Delay
+
-
V
OCP
+
-
+
-
+
-
+
-
-Q
Q
R
S
LV
CC
<5V
Latch
Protection
-Q
Q
R
S
Auto-restart
Protection
+
-
0.4 / 0.6 V
5V
23 V
0.58 V
0.9 V
8.7 / 9.2V
HV
CC
good
+
-
I
CTC
+
-
+
-
3V
1V
-Q
Q
R
S
F/F
Level-Shift
Balancing
Delay
Shutdown without delay
50ns Delay
-1
2I
CTC
V
REF
I
CTC
350ns
350ns
10
SG
Delay
1.5µs
2V
+
-
Counter (1/4)
LV
CC
I
OLP
14
LO
Figure 2. Internal Block Diagram