LT1424-5
Isolated Flyback
Switching Regulator
with 5V Output
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FEATURES
DESCRIPTIO
The LT®1424-5 is a monolithic high power switching
regulator specifically designed for the isolated flyback
topology. No “third winding” or optoisolator is required;
the integrated circuit senses the isolated output voltage
directly from the primary side flyback waveform. A high
current, high efficiency switch is included on the die along
with all oscillator, control and protection circuitry.
■
No Transformer “Third Winding” or Optoisolator
Required
■
Designed for Use with 1:1 Ratio Transformers
■
Fixed, Application Specific 5V Output Voltage
■
Regulation Maintained Well into Discontinuous
Mode (Light Load)
■
Load Compensation Provides Excellent
Load Regulation
The LT1424-5 operates with input supply voltages from
3V to 20V and draws only 7mA quiescent current. It can
deliver up to 400mA at 5V with no external power devices.
By utilizing current mode switching techniques, it pro-
vides excellent AC and DC line regulation.
■
Available in 8-Pin PDIP and SO Packages
■
Operating Frequency: 285kHz
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APPLICATIO S
TheLT1424-5hasanumberoffeaturesnotfoundonother
switching regulator ICs. Its unique control circuitry can
maintain regulation well into discontinuous mode. Load
compensation circuitry allows for improved load regula-
tion. An externally activated shutdown mode reduces total
supply current to 20µA typical for standby operation.
■
Isolated Communication Supplies
■
Industrial Automation
■
Instrumentation Systems
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATIO
5V Output Isolated Power Supply
Load Regulation
5.25
330pF
47Ω
ISOLATION
BARRIER
MBRS130LT3
5V
T1
5V
400mA
+
C1
100µF
10V
0.1µF
6
3
4
1N5248
47Ω
330pF
•
5.00
+
C2
1
2
8
7
SHDN
R
1.8k
100µF
CCOMP
V
IN
10V
V
C
•
•
MBR0540T4
7
LT1424-5
1
2
3
4
6
5
OUT
COM
SYNC
SGND
V
SW
PGND
1000pF
1424-5 TA01
0.1µF
C1, C2: AVX TPS D107M010R0080
T1: DALE LPE-4841-A307
INPUT
COM
4.75
0
100
200
300
400
OUTPUT CURRENT (mA)
1424-5 TA02
sn14245 14245fs
1