LT1777C View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LT1777C' PDF : 24 Pages View PDF
LT1777
TYPICAL APPLICATION
Minimum PC Board Size Application
The previously described basic applications employ power
path parts which are capable of delivering the full rated
input supply voltage and output current capabilities of the
LT1777. A substantial improvement in printed circuit
board area requirements can be achieved with the circuit
shown below. This uses a physically smaller and less
costly power inductor and a tantalum input capacitor. This
circuit is capable of delivering up to 300mA at 5V, from
input voltages as high as 28V. The only disadvantage is
that due to the increased resistance in the inductor, the
circuit is no longer capable of withstanding indefinite short
circuits to ground. The LT1777 will still current limit at its
nominal ILIM value, but this will overheat the inductor.
Momentary short circuits of a few seconds or less can still
be tolerated.
Minimum PC Board Area Application
VIN
10V TO 28V + C1
22µF
35V
C6
0.1µF
10
VIN
3
4
C5
SHDN VCC
100pF
LT1777
12
6
L1
0µH TO 2.2µH
(SEE BELOW)
L2
200µH
SYNC VSW
14
VC
5
VD
+ C2
C4
R3
100pF 12k
13
FB
D1
100µF
10V
C3
SGND
2200pF
7
C1: AVX E CASE TPSE226M035R0300
C2: AVX D CASE TPSD107M010R0080
C3, C4, C5: NPO OR X7R
C6, C7: Z5U
D1: MOTOROLA 100V, 1A SMD SCHOTTKY
MBRS1100
L1: SENSE INDUCTOR CAN VARY FROM 0µH TO 2.2µH
AS PER APPLICATION. SEE PREVIOUS SCHEMATICS
FOR EXAMPLES
L2: COILCRAFT CTX200-1 OR SIMILAR
C7
0.1µF
VOUT
5V
R1
36.5k
1%
R2
12.1k
1%
1777 TA03
RELATED PARTS
PART NUMBER
LT1076
LT1533
LT1534
LT1576
LTC1622
LTC1624
LT1676/LT1776
DESCRIPTION
COMMENTS
100kHz, 2A Step-Down Switching Regulator
Ultralow Noise 1A Switching Regulator
Integrated 2A Switch, VIN Up to 46V
Push-Pull Design for Low Noise Isolated Supplies
Ultralow Noise 2A Switching Regulator
Ultralow Noise Regulator for Boost Topologies
200kHz, 1.5A Step-Down Switching Regulator
Output Up to 1.25A, Integrated Switch, SO-8 Package
Low VIN Step-Down DC/DC Controller
Fixed Frequency 550kHz Operation, MSOP Package
High Efficiency SO-8 DC/DC Controller
200kHz Operation, VIN from 3.5V to 36V, SO-8 Package
Wide Input Range, High Efficiency, Step-Down Voltage Regulator 7.4V to 60V Input, 100/200kHz Operation, 700mA Internal Switch
24 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX:(408)434-0507 q www.linear-tech.com
1777f LT/TP 0899 4K • PRINTED IN USA
© LINEAR TECHNOLOGY CORPORATION 1999
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