LT1074I Datasheet, PDF (13/16 Pages) Linear Technology – Step-Down Switching Regulator

TYPICAL APPLICATIO S
LT1074/LT1076
V_IN
20V^† TO 35V
+
Tapped-Inductor Buck Converter
V_IN
V_SW
LT1074HV
GND
C3
200µF
50V
FB
V_C
R3
1k
C2
0.2µF
L1*
3
D2
35V
5W
1
D1**
R1
2.8k
+
D3
1N5819
R2
2.21k
0.01µF
L2
5µH
C1
4400µF
(2 EA
2200µF, +
16V)
V_OUT
5V, 10A^†
C4
390µF
16V
* PULSE ENGINEERING #PE±65282
** MOTOROLA MBR2030CTL
† _{IF INPUT VOLTAGE IS BELOW 20V,}
MAXIMUM OUTPUT CURRENT WILL BE REDUCED. SEE AN44
LT1074 •TA02
Positive-to-Negative Converter with 5V Output
V_IN
4.5V to
+ ^40V
+ _C1
220µF
50V
L1
25µH
5A^††
V_{IN VSW}
LT1074
GND
V_C ^VFB
C3
0.1µF
R1**
5.1k
R2**
10k
D1^†
MBR745
C4**
0.01µF
R3*
2.74k
+
R4
1.82k*
C2
1000µF
10V
OPTIONAL FILTER
5µH _–
200µF
+ ^10V
–5V,1A***
* = 1% FILM RESISTORS
D1 = MOTOROLA-MBR745
C1 = NICHICON-UPL1C221MRH6
C2 = NICHICON-UPL1A102MRH6
L1 = COILTRONICS-CTX25-5-52
† _{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_C PIN.
R3 = V_OUT –2.37 (KΩ)
R1 = (R3) (1.86)
R2 = (R3) (3.65)
** 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.
LT1074 • TA03
sn1074 1074fds
13