1

dc2138bfa

DEMO MANUAL DC2138B

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

Converter with 65V/1.2A Switch

Demonstration circuit 2138B is an isolated flyback con-

verter featuring the LT®8301. 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

The Performance Summary table summarizes the perfor-

mance of the demo board at room temperature. The demo

circuitcanbeeasilymodifiedfordifferentapplicationswith

some pre-designed transformers.

The DC2138B 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 monolithic isolated flyback

converter. No third winding or opto-isolator is required for

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

regulation. The part sets the isolated output voltage with a

single external resistor and integrates loop compensation

and soft-start circuitry inside the IC. Boundary mode op-

eration provides a small magnetic solution with improved

tains 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 2138B.

Design files for this circuit board are available at

http://www.linear.com/demo/DC2138B