1
dc2138af
DEMO MANUAL DC2138A
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Input Voltage
10
24
32
V
Standby Current
IOUT = 0mA, VIN = 24V, VOUT = 5V
950
µA
Output Voltage
VIN = 12V to 32V, IOUT = 6mA to 700mA
4.75
5
5.25
V
Maximum Output Current
VIN = 12V
VIN = 24V
700
1000
mA
mA
Output Voltage Ripple (Peak to Peak)
VIN = 24V, IOUT = 1A
90
mV
Switching Frequency
VIN = 24V, IOUT = 1A
190
kHz
Efficiency
VIN = 24V, IOUT = 1A
83.2
%
Description
LT8301
42V
IN
Micropower Isolated Flyback
Converter with 65V/1.2A Switch
Demonstration circuit 2138A is an isolated flyback con-
verter featuring the
. This demo circuit outputs
5V from a 10V to 32V input, with a nominal of 24V. The
output current capability increases with the input voltage.
The standby input current of the demo circuit is less than
950µA (typical) at V
IN
= 24V.
The Performance Summary table summarizes the perfor-
mance of the demo board at room temperature. The demo
circuit can be easily modified for different applications with
some pre-designed transformers.
The DC2138A needs a very small minimum load (~6mA)
to regulate the output voltage, thanks to the accurate
current limit capability and ultralow switching frequency
of LT8301 at very light load. On the board, a Zener diode
is placed on the output to clamp the voltage to ~5V. This
Zener is optional, and can be replaced with a 0.8k resistor.
The LT8301 is a simple-to-use high-voltage monolithic
isolated flyback converter. No third winding or opto-isolator
L
, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
performance summary
is required for regulation. The part sets the isolated output
voltage with a single external resistor and integrates loop
compensation and soft-start circuitry inside the IC. Bound-
ary mode operation provides a small magnetic solution
with improved load regulation. Low-ripple Burst Mode
®
operation maintains high efficiency at light loads while
minimizing the output voltage ripple. A 1.2A, 65V DMOS
power switch is integrated along with all high-voltage
circuitry and control logic into a 5-lead ThinSOT™ package.
The LT8301 data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this quick start
guide for demo circuit 2138A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2138A
Specifications are at T
A
= 25°C
