Datasheet

LT3758/LT3758A
31
3758afd
typicAl ApplicAtions
18V to 72V Input, 24V Output SEPIC Converter
SENSE
LT3758A
V
IN
V
IN
18V TO 72V
C
IN2
2.2µF
100V
X7R
C
DC
2.2µF
100V
X7R, ×2
V
OUT
24V
1A
0.025Ω
M1
41.2k
300kHz
GATE
FBX
GND
INTV
CC
SHDN/UVLO
SYNC
RT
SS
•
•
232k
20k
0.47µF
10nF
10k
L1A
L1B
D1
C
IN1
: PANASONIC EEE2AA100UP
C
IN2
, C
DC
: TAIYO YUDEN HMK325B7225KN-T
C
OUT1
: MURATA GRM31CR61E106KA12L
C
OUT2
: KEMET T495X336K035AS
3758 TA06a
280k
1%
20k
1%
C
OUT1
10µF
25V
X5R
×4
C
VCC
4.7µF
10V
X5R
L1A, L1B: COILTRONICS DRQ127-470
M1: FAIRCHILD SEMICONDUCTOR FDMS2572
D1: ON SEMICONDUCTOR MBRS3100T3G
V
C
C
IN1
10µF
100V
C
OUT1
33µF
35V
×2
+
+
Efficiency vs Output Current
OUTPUT CURRENT (A)
0.001
10
EFFICIENCY (%)
30
20
40
50
60
70
80
90
100
0.01
0.1
3758 TA06b
1
V
IN
= 72V
V
IN
= 48V
V
IN
= 18V
Load Step Waveform
500µs/DIV
V
OUT
2V/DIV
AC-COUPLED
I
OUT
1A/DIV
0A
1A
3758 TA06c
V
IN
= 48V
Start-Up Waveform
2ms/DIV
V
OUT
10V/DIV
IL
1A +
IL
1B
1A/DIV
3758 TA06d
V
IN
= 48V
50µs/DIV
V
SW
50V/DIV
V
OUT
20V/DIV
IL
1A +
IL
1B
2A/DIV
3758 TA06e
V
IN
= 48V
Frequency Foldback Waveforms
When Output Short-Circuit