Datasheet

11
LT1072
1072fc
Positive to Negative Buck-Boost Converter
External Current Limit
LT1072 • TA08
D1
R1
500Ω
R2
≈ 2V
V
X
V
C
GND
LT1072
Voltage Boosted Boost Converter
LT1072 • TA09
D2
D1
TOTAL INDUCTANCE = 8mH
INTERLEAVE PRIMARY AND
SECONDARY FOR LOW LEAKAGE
INDUCTANCE
1
L1
N = 5
+
C2
0.047µF
R3
10k
V
IN
15V
C1
200µF
R4
1.5k
1/2W
C3
0.68
R1
98k
V
OUT
100V AT 75mA
R2
1.24k
V
IN
V
SW
FB
V
C
GND
LT1072
+
C
C5
100µF*
V
IN
10 TO 30V
*REQUIRED IF INPUT LEADS ≥ 2"
**PULSE ENGINEERING 92113
†
TO AVOID START-UP PROBLEMS
FOR INPUT VOLTAGES BELOW 10V,
CONNECT ANODE OF D3 TO V
IN
,
AND REMOVE R5. C1 MAY BE
REDUCED FOR LOWER OUTPUT
CURRENTS. C1 ≈ (500µF)(I
OUT
).
FOR 5V OUTPUTS, REDUCE R3
TO 1.5k, INCREASE C2 TO 0.3µF,
AND REDUCE R6 TO 100Ω
LT1072 • TA07
R4
47Ω
D1
D2
1N914
C1
†
1000µF
C
C3
2µF
R5
†
470Ω, 1W
C
C2
0.1µF
D3
†
1N4001
C4
5µF
R6
470Ω
R2
1.24k
L1**
200µH
R3
5k
V
OUT
–12V AT 2A
R1
10.7k
V
IN
V
SW
FB
V
C
GND
LT1072
+
+
+
TYPICAL APPLICATIO S
U