LTC1871 Linear Technology, LTC1871 Datasheet - Page 33

• Manufacturer Part Number: LTC1871
• Description: Wide Input Range/ No RSENSE Current Mode Boost/ Flyback and SEPIC Controller
• Manufacturer: Linear Technology

TYPICAL APPLICATIO S
54.9k
1%
R2
1V/DIV
8.2nF
V
C
C
47pF
OUT
C1
12k
C2
R
4.7nF
C
C1
Q1
154k
1%
R3
R6
750
4.5V to 28V Input, 5V/2A Output SEPIC Converter with Undervoltage Lockout and Soft-Start
49.9k
1%
R4
100
115k
R5
Soft-Start
1%
R1
1ms/DIV
R
162k
1%
T
C
C
C
C
C
1
2
3
4
5
IN1
IN2
OUT1
OUT2
VCC
C2
1 F
X5R
1A/DIV
RUN
I
FB
FREQ
MODE/SYNC
TH
, C
:
100mV/DIV
(DC)
:
I
U
OUT
:
:
DC
: TAIYO YUDEN GMK325BJ225MN
LTC1871
V
AVX TPSE226M035R0300
SANYO 6TPB330M
TAIYO YUDEN JMK325BJ226MN
LMK316BJ475ML
2.2A
0.5A
(AC)
OUT
INTV
1871 TA02b
SENSE
GATE
NOTES:
GND
V
1. V
2. SOFT-START dV
Load Step Response at V
CC
IN
V
IN
IN
10
9
8
7
6
UVLO
UVLO
+
–
= 3.86V
= 4.17V
C
4.7 F
10V
X5R
VCC
250 s/DIV
OUT
/dt = 5V/6ms
1A/DIV
D1:
L1, L2: BH ELECTRONICS BH510-1007 (*COUPLED INDUCTORS)
M1:
Q1:
(DC)
C
2.2 F
35V
X5R
100mV/DIV
I
OUT
IN1
IN
V
2.2A
0.5A
(AC)
+
INTERNATIONAL RECTIFIER 30BQ040
SILICONIX/VISHAY Si4840
PHILIPS BC847BF
OUT
= 28V
C
22 F
35V
1871 TA02d
IN2
Load Step Response at V
L1*
•
M1
2.2 F
X5R
C
25V
DC
3
•
250 s/DIV
L2*
D1
+
C
330 F
6.3V
IN
OUT1
= 4.5V
1871 TA02a
LTC1871
1871 TA02c
C
22 F
6.3V
X5R
OUT2
GND
V
4.5V to 28V
V
5V
2A
(3A TO 4A PEAK)
IN
OUT
33