lt3958 Linear Technology Corporation, lt3958 Datasheet - Page 8

• Manufacturer Part Number: lt3958
• Description: High Input Voltage, Boost, Flyback, Sepic And Inverting Converter
• Manufacturer: Linear Technology Corporation

LT3958
8
BLOCK DIAGRAM
V
OUT
R2
31
–0.88V
R1
1.72V
FBX
–0.8V
1.6V
–
+
–
+
FREQUENCY
FOLDBACK
A11
A12
+
–
+
–
A1
A2
C
C2
G6
2.5V
30
Figure 1. LT3958 Block Diagram Working as a SEPIC Converter
R
VC
C
C
C1
I
S3
2.5V
32
2μA
I
S1
1.28V
SS
C
FREQUENCY
FOLDBACK
Q3
SS
I
10μA
S2
Q2
–
+
A3
G4
UVLO
REGULATOR
34
V
PWM
COMPARATOR
AND UVLO
INTERNAL
C
1.2V
V
SYNC
IN
–
+
A7
+
+
–
G1
165˚C
G3
TLO
A10
A4
R4
–
+
FREQ
PROG
SLOPE
25
RAMP
100kHz-1MHz
OSCILLATOR
GENERATOR
1.22V
G5
A8
A9
EN/UVLO
R3
RAMP
+
–
+
–
33
Q1
12.8V
R
RT
V
T
3.75V
ISENSE
R
CURRENT
7.2V LDO
LIMIT
SR1
S
C
IN
O
DRIVER
A6
A5
–
+
+
–
G2
27
48mV
SENSE
V
INTV
IN
24, 37
L1
4, 23,
CC
M1
8, 9, 20,
21, 38
12, 13, 14,
15, 16, 17
R
SW
SGND
SENSE
C
DC
3958 F01
28
6
3
•
INTV
SENSE1
GND
SENSE2
L2
CC
D1
C
VCC
C
V
OUT
3958f
OUT