LT1074 Linear Technology, LT1074 Datasheet - Page 13

• Manufacturer Part Number: LT1074
• Description: Step-Down Switching Regulator
• Manufacturer: Linear Technology

TYPICAL APPLICATIO S
* = 1% FILM RESISTORS
D1 = MOTOROLA-MBR745
C1 = NICHICON-UPL1C221MRH6
C2 = NICHICON-UPL1A102MRH6
L1 = COILTRONICS-CTX25-5-52
20V
†
TO 35V
V
IN
**
+
*
†
PULSE ENGINEERING #PE 65282
MOTOROLA MBR2030CTL
IF INPUT VOLTAGE IS BELOW 20V,
MAXIMUM OUTPUT CURRENT WILL BE REDUCED. SEE AN44
+
U
C3
200 F
50V
**
**
††
†
GND
V
4.5V to
40V
IN
V
R3 =
R1 = (R3) (1.86)
R2 = (R3) (3.65)
LOWER REVERSE VOLTAGE RATING MAY BE USED FOR LOWER INPUT VOLTAGES.
LOWER CURRENT RATING IS ALLOWED FOR LOWER OUTPUT CURRENT. SEE AN44.
LOWER CURRENT RATING MAY BE USED FOR LOWER OUTPUT CURRENT. SEE AN44.
R1, R2, AND C4 ARE USED FOR LOOP FREQUENCY COMPENSATION WITH LOW INPUT VOLTAGE,
BUT R1 AND R2 MUST BE INCLUDED IN THE CALCULATION FOR OUTPUT VOLTAGE DIVIDER VALUES.
FOR HIGHER OUTPUT VOLTAGES, INCREASE R1, R2, AND R3 PROPORTIONATELY.
FOR INPUT VOLTAGE > 10V, R1, R2, AND C4 CAN BE ELIMINATED, AND COMPENSATION IS
DONE TOTALLY ON THE V PIN.
MAXIMUM OUTPUT CURRENT OF 1A IS DETERMINED BY MINIMUM INPUT
VOLTAGE OF 4.5V. HIGHER MINIMUM INPUT VOLTAGE WILL ALLOW MUCH HIGHER
OUTPUT CURRENTS. SEE AN44.
IN
GND
Positive-to-Negative Converter with 5V Output
LT1074
LT1074HV
V
V
OUT
IN
V
C
–2.37 (K )
Tapped-Inductor Buck Converter
V
V
V
C
SW
C3
0.1 F
FB
V
R3
1k
SW
FB
+
C2
0.2 F
C1
220 F
50V
C
D3
1N5819
D2
35V
5W
L1
25 H
5A
D1
MBR745
3
††
†
L1*
R2**
10k
R1**
5.1k
1
D1**
0.01 F
C4**
0.01 F
R1
2.8k
R2
2.21k
R3*
2.74k
R4
1.82k*
+
+
C1
4400 F
(2 EA
2200 F,
16V)
5 H
L2
C2
1000 F
10V
LT1074 • TA03
+
–5V,1A***
LT1074/LT1076
OPTIONAL FILTER
5 H
C4
390 F
16V
V
5V, 10A
LT1074 •TA02
OUT
†
–
+
200 F
10V
13