LT1777IS#PBF Linear Technology, LT1777IS#PBF Datasheet - Page 24

• Manufacturer Part Number: LT1777IS#PBF
• Description: IC REG SW BUCK LO NOISE 16-SOIC
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LT1777IS#PBF

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.24 ~ 30 V
• Current - Output: 700mA
• Frequency - Switching: 100kHz
• Voltage - Input: 12 ~ 48 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (3.9mm Width)
• Primary Input Voltage: 48V
• No. Of Outputs: 1
• Output Voltage: 40.8V
• Output Current: 1A
• No. Of Pins: 16
• Operating Temperature Range: -40°C To +125°C
• Msl: MSL 1 - Unlimited
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -

RELATED PARTS
PART NUMBER
LT1076
LT1533
LT1534
LT1576
LTC1622
LTC1624
LT1676/LT1776
LT1777
TYPICAL
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
24
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] FAX: [phone] www.linear-tech.com
APPLICATION
DESCRIPTION
100kHz, 2A Step-Down Switching Regulator
Ultralow Noise 1A Switching Regulator
Ultralow Noise 2A Switching Regulator
200kHz, 1.5A Step-Down Switching Regulator
Low V
High Efficiency SO-8 DC/DC Controller
Wide Input Range, High Efficiency, Step-Down Voltage Regulator 7.4V to 60V Input, 100/200kHz Operation, 700mA Internal Switch
10V TO 28V
IN
Step-Down DC/DC Controller
V
IN
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
+
C1
22 F
35V
U
C4
100pF
C6
0.1 F
R3
12k
Minimum PC Board Area Application
C5
100pF
C3
2200pF
12
14
3
SHDN
SYNC
V
C
LT1777
SGND
L1: SENSE INDUCTOR CAN VARY FROM 0 H TO 2.2 H
L2: COILCRAFT CTX200-1 OR SIMILAR
V
IN
10
7
AS PER APPLICATION. SEE PREVIOUS SCHEMATICS
FOR EXAMPLES
V
V
SW
V
CC
FB
D
4
6
5
13
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 I
Momentary short circuits of a few seconds or less can still
be tolerated.
0 H TO 2.2 H
(SEE BELOW)
L1
COMMENTS
Integrated 2A Switch, V
Push-Pull Design for Low Noise Isolated Supplies
Ultralow Noise Regulator for Boost Topologies
Output Up to 1.25A, Integrated Switch, SO-8 Package
Fixed Frequency 550kHz Operation, MSOP Package
200kHz Operation, V
LIM
D1
200 H
L2
value, but this will overheat the inductor.
+
IN
C2
100 F
10V
from 3.5V to 36V, SO-8 Package
IN
Up to 46V
C7
0.1 F
LINEAR TECHNOLOGY CORPORATION 1999
1777f LT/TP 0899 4K • PRINTED IN USA
R1
36.5k
1%
R2
12.1k
1%
1777 TA03
V
5V
OUT