LTC3703 Linear Technology, LTC3703 Datasheet - Page 17

• Manufacturer Part Number: LTC3703
• Description: 100V Synchronous Switching Regulator Controller
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
is above the input supply: V
value of the boost capacitor C
of the total input capacitance of the top side MOSFET(s).
The reverse breakdown of the external diode, D
greater than V
for the external diode is the reverse recovery and reverse
leakage, either of which may cause excessive reverse
current to flow at full reverse voltage. If the reverse
current times reverse voltage exceeds the maximum
R1
R2
Figure 10c. Secondary Output Loop and V
Figure 10a. V
V
DRV
CC
OPTIONAL V
CONNECTION
10V < V
V
DRV
FCB
GND
CC
CC
LTC3703
+
CC
LTC3703
SEC
BGRTN
1 F
< 15V
CC
IN(MAX)
BGRTN
SW
V
BG
TG
IN
CC
TG1
BG1
SW
V
IN
Generated from 10V < V
U
. Another important consideration
V
IN
V
+
IN
U
+
C
BOOST
B
IN
needs to be 100 times that
C
L1
IN
N
1
W
= V
12V
T1
IN
CC
OUT
12V
Connection
+ V
< 15V
+
DRVCC
U
B
+
+
, must be
3703 F10a
V
10V TO
15V
C
OUT
OUT
3703 F10c
V
1 F
C
. The
V
OUT
SEC
OUT
V
DRV
allowable power dissipation, the diode may be damaged.
For best results, use an ultrafast recovery silicon diode
such as the BAS21.
An internal undervoltage lockout (UVLO) monitors the
voltage on DRV
cient gate drive voltage. If the DRV
the UVLO threshold, the LTC3703 shuts down and the gate
drive outputs remain low.
CC
12V
CC
LTC3703
Figure 10d. Capacitive Charge Pump for V
+
V
DRV
CC
Figure 10b. V
BGRTN
CC
1 F
LTC3703
SW
V
BG
TG
C
IN
IN
+
BGRTN
CC
V
SW
V
BG
TG
C
IN
IN
IN
to ensure that the LTC3703 has suffi-
CC
+
V
Generated from V
IN
C10
1 F
16V
(<40V)
L1
ZHCS400
R17
1M
1%
R17
110k
1%
BAT85
D2
L1
12V
FB
SW
VN2222LL
CC
LT1613
OUT
10 H
+
GND
voltage falls below
L2
0.22 F
LTC3703
CC
< 10V
SHDN
C
(V
OUT
V
IN
IN
+
< 40V)
BAT85
BAT85
C
3703 F10d
V
17
OUT
OUT
3703 F10b
V
<10V
OUT
3703f
C9
4.7 F
6.3V