LT1172MJ8 Linear Technology, LT1172MJ8 Datasheet - Page 12

• Manufacturer Part Number: LT1172MJ8
• Description: SP-SWREG/Monolithic, 100kHz 5A 2.5A And 1.25A High Efficiency Switching Regulato
• Manufacturer: Linear Technology

LT1 170/LT1 171/LT1172
12
TYPICAL APPLICATIO S
> V
INPUT VOLTAGE
INPUT VOLTAGE
BAT
+ 2V < 35V
4.5V TO 20V
200 F
1N4001
35V
TANT
D3
C1
10 F
1 F
†
†
C4
+
+
+
SHUTDOWN = 5V
TANTALUM
1N5819
RUN = 0V
2.2 F
35V
GND
C2
E2
E1
D1
+
GND
LT1170
V
IN
LT1172
2 F
1k
V
U
78k
R6
470 , 1W
IN
V
C
R5
R3
5k
V
V
1N5818
C2
0.1 F
SW
FB
V
†
C
V
IN
Backlight CCFL Supply (see AN45 for details)
SW
V
Positive-to-Negative Buck-Boost Converter
R7
22k
SW
High Efficiency Constant Current Charger
GND
FB
LT1171
2N3904
R2
1.24k
50 H
1 F
L1**
10.7k
R8
1k
C6
R1
+
+
+
300 H
V
L1**
C
***
C3
0.47 F
D2
MBR340
FB
C5
100 F*
1N914
C3
2 F
**
*
D2
†
Q1,Q2 = BCP56 OR MPS650/561
COILTRONICS CTX300-4
SUMIDA 6345-020 OR COILTRONICS 110092-1
A MODIFICATION WILL ALLOW OPERATION DOWN TO 4.5V. CONSULT FACTORY.
D1
V
10V TO
30V
IN
47
R4
0.02 F
Q1*
Q2*
C4
0.01 F
R2
1k
+
B
A
C1
1000 F
**
*
†
†
REQUIRED IF INPUT LEADS 2"
PULSE ENGINEERING 92114, COILTRONICS 50-2-52
TO AVOID STARTUP PROBLEMS FOR INPUT VOLTAGES
BELOW 10V, CONNECT ANODE OF D3 TO V
REMOVE R5. C1 MAY BE REDUCED FOR LOWER OUTPUT
CURRENTS. C1 (500 F)(I
FOR 5V OUTPUTS, REDUCE R3 TO 1.5k, INCREASE C2 TO
0.3 F, AND REDUCE R6 TO 100 .
V
V
LT1006
+
–
L2***
0.05
R6
470
–
+
25k
R3
R5
1N914
V
–12V
2A
33pF
D1
OUT
3kV
10k
R3
R4
1k
100 H, 1A
I
OUT
CHRG
L1
* L2 REDUCES RIPPLE CURRENT INTO
THE BATTERY BY ABOUT 20 :1.
IT MAY BE OMITTED IF DESIRED.
LAMP
).
=
+
1.244V • R4
D2
1N914
560
R1
R3 • R5
C4
200 F
25V
10 H, 1A
IN
1170/1/2 TA10
L2*
, AND
1170/1/2 TA12
1A
INTENSITY
ADJUST
= 1A AS SHOWN
50k
+
BATTERY
2V TO 25V
1170/1/2 TA11