LT1172MJ8 Linear Technology, LT1172MJ8 Datasheet - Page 11

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

TYPICAL APPLICATIO S
**
*
INPUT FILTER
REQUIRED IF INPUT LEADS 2"
PULSE ENGINEERING 92114
COILTRONICS 50-2-52
**
OPTIONAL
*
†
REQUIRED IF INPUT LEADS 2"
PULSE ENGINEERING 92114, COILTRONICS 50-2-52
THIS CIRCUIT IS OFTEN USED TO CONVERT –48V TO 5V. TO GUARANTEE
FULL SHORT-CIRCUIT PROTECTION, THE CURRENT LIMIT CIRCUIT SHOWN
IN AN19, FIGURE 39, SHOULD BE ADDED WITH C1 REDUCED TO 200pF.
–20V
L3
V
IN
10V TO
100 F
20V
C4*
Negative-to-Positive Buck-Boost Converter
(for Off-Line Applications, See AN25)
+
INPUT FILTER
+
OPTIONAL
Driving High Voltage FET
L3
–20V
V
IN
GND
100 F
LT1170
C3*
LT1170
GND
V
V
IN
IN
+
U
V
C
50 H
L1**
R3
2.2k
V
V
SW
C1
0.22 F
SW
FB
(Note that maximum output currents are divided by 2 for LT1171, by 4 for LT1172.)
GND
LT1170
V
R2
1.24k
D1
IN
D1
G
1170/1/2 TA05
Negative Buck Converter
OPTIONAL
+
OUTPUT
V
FILTER
C
V
R3
D
Q1
SW
L2
†
FB
C2
1000 F
C1
Q1
R2
1.24k
C3
R1
11.3k
1170/1/2 TA07
D1
50 H
L1**
V
12V
2A
OUT
+
C2
1000 F
500
2N3906
R2
R1
Q1
V
X
NOTE THAT THE LT1170
GND PIN IS NO LONGER
COMMON TO V
–
+
Q1
LT1 170/LT1 171/LT1172
V
R1
4.64k
IN
2V
D1
12k
R4
OPTIONAL
External Current Limit
External Current Limit
OUTPUT
FILTER
GND
LOAD
IN
C1
1000pF
–
4 H
R1
L2
1k
.
R
S
LT1170
–5.2V
4.5A
1170/1/2 TA09
GND
+
LT1170
C4
200 F
1170/1/2 TA06
V
V
IN
C
V
C
R2
V
SW
C2
FB
1170/1/2 TA08
11