LT1952IGN Linear Technology, LT1952IGN Datasheet - Page 20

• Manufacturer Part Number: LT1952IGN
• Description: IC,SMPS CONTROLLER,CURRENT-MODE,SOP,16PIN,PLASTIC
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
LT1952/LT1952-1
20
Figure 12. LT1952-Based Synchronous Forward Converter
100k
0.1µF
Efficiency vs Load Current (For Circuit in Figure 14)
Q1: PHM15NQ20 PHILIPS
98
96
94
92
90
88
86
SOUT
22k
0
115k
0.1µF
16
5
6
2
3
4
5
U
SOUT
SS_MAXDC
V
FB
R
SYNC
BLANK DELAY
REF
OSC
LOAD CURRENT (A)
9
40k
LT1952-1
10
U
Figure 14. 36V to 72V Input to 5V at 20A Synchronous Forward Converter
12
33k
SD_V
I
COMP
PGND
SENSE
15
GND
OUT
0.1µF
SEC
V
OC
IN
1µF
V
V
f
OSC
IN
OUT
10V
7
14
11
10
13
8
15
1
W
= 48V
20
= 300kHz
= 5V
BIAS
1952 F12
25
36V TO 72V
9.53k
4.75k
6
5
4
10V
HCPL-M453
U
+V
BIAS
IN
SOUT
475k
18.2k
1
2
3
220pF
1k
2.2µF
100V
(200mV/DIV)
T2
X5R
C
IN
(5A/DIV)
Figure 13. Output Voltage Transient Response
V
I
Q1
OUT
OUT
560Ω
0.015Ω
0A
SYNC
PA0491
(6A to 12A Load Step at 6A/µs)
T1
X5R
+V
1µF
C9, 6.8nF
0UT
7V
BIAS
Q2
PH3830
38.3k
270Ω
R14
1.2k
R15
20µs/DIV
R13
1
2
3
4
5
6
8
R16
12.4k
V
CG
PGND
GND
OPTO
V
V
DD
COMP
FB
LTC1698
Q3
PH3830
1952 F13
PA1393.152
I
SYNC
–I
+I
COMP
V
OVP
AUX
SNS
SNS
FG
L1
16
15
14
13
12
11
9
SYNC
1952 F14
C
100µF
X5R
2×
19521fb
+V
5V
20A
01
0.1µF
0UT