LT1424-5 Datasheet, PDF (1/16 Pages) Linear Technology – Isolated Flyback Switching Regulator with 5V Output

LT1424-5
Isolated Flyback
Switching Regulator
with 5V Output
FEATURES
s _{No Transformer “Third Winding” or Optoisolator}
Required
s _{Designed for Use with 1:1 Ratio Transformers}
s _{Fixed, Application Specific 5V Output Voltage}
s _{Regulation Maintained Well into Discontinuous}
Mode (Light Load)
s _{Load Compensation Provides Excellent}
Load Regulation
s _{Available in 8-Pin PDIP and SO Packages}
s _{Operating Frequency: 285kHz}
U
APPLICATIO S
s _{Isolated Communication Supplies}
s _{Industrial Automation}
s _{Instrumentation Systems}
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.
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.
The LT1424-5 has a number of features not found on other
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
5V
+ C1
100µF
10V
INPUT
COM
1000pF
5V Output Isolated Power Supply
0.1µF
1
8
2 ^{SHDN RCCOMP} 7
V_C
V_IN
LT1424-5
3
6
SYNC
4
V_{SW 5}
SGND PGND
ISOLATION
BARRIER
T1
47Ω
MBRS130LT3
1N5248
47Ω
6
•
34
+
MBR0540T4
330pF
7
••
12
0.1µF
C1, C2: AVX TPS D107M010R0080
T1: DALE LPE-4841-A307
330pF
5V
400mA
C2
100µF 1.8k
10V
OUT
1424-5 TA01 ^COM
Load Regulation
5.25
5.00
4.75
0
100
200
300
400
OUTPUT CURRENT (mA)
1424-5 TA02
sn14245 14245fs
1