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DESCRIPTION
Demonstration circuit 1694B is an isolated flyback con-
verter featuring the
LT
3748. The demo circuit is designed
®
for a 12V output from a 22V to 75V DC input. The output
current is up to 2.5A. The part senses the isolated output
voltage directly from the primary side flyback waveform
during the off time of the power switch. No third winding,
opto-coupler, or signal transformer is required for regula-
tion. A minimum load of approximately 2% of maximum
load is required on the output to maintain regulation.
The demo circuit can be easily modified for applications
of different input, and output voltage/current, with some
pre-designed transformers from vendors such as Würth
Electronics, Sumida, Pulse Engineering and Coilcraft. Both
EP13 and EFD20 core transformers can be assembled on
the board. A two-stage filter is optional for applications
requiring very small output ripple.
PERFORMANCE SUMMARY
PARAMETER
Input Voltage Range
Output Voltage
Maximum Output Current
Output Voltage Ripple (Peak-to-Peak)
Switching Frequency
Efficiency
DEMO MANUAL DC1694B
The LT3748 is a high input voltage isolated flyback con-
troller operating with input supply voltages from 5V to
100V, and 1.9A average gate drive source and sink current.
The LT3748 utilizes boundary mode operation to provide
a high efficiency, small size solution with improved load
regulation of ±5% over the full line, load and temperature
ranges. The LT3748 can be used in a wide variety of indus-
trial, automotive, medical, telecom, data-com applications,
where regulated isolated output is required.
The LT3748 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 1694B.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1694B
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Specifications are at T
= 25°C
A
CONDITIONS
V
= 22V to 75V
IN
I
= 50mA to 2.5A
OUT
V
= 22V to 75V
IN
V
= 22V to 75V, I
= 2.5A
IN
OUT
V
= 48V, I
= 2.5A
IN
OUT
V
= 48V, I
= 2.5A
IN
OUT
100V Isolated
Flyback Converter
MIN
TYP
22
48
11.4
12
2.5
289
86.5
LT3748
MAX
UNITS
75
V
12.6
V
A
420
mV
kHz
%
dc1694bfa
1
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Related Manuals for Linear Technology DC1694B
Summary of Contents for Linear Technology DC1694B
- Page 1 A two-stage filter is optional for applications http://www.linear.com/demo/DC1694B requiring very small output ripple. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. PERFORMANCE SUMMARY Specifications are at T = 25°C...
- Page 2 DEMO MANUAL DC1694B QUICK START PROCEDURE Demo circuit 1694B is easy to set up to evaluate the NOTE: If higher operating voltage is required, power performance of the LT3748. Refer to Figure 1 for proper components with higher voltage ratings should be used.
-
Page 3: Quick Start Procedure
DEMO MANUAL DC1694B QUICK START PROCEDURE Figure 1. Proper Measurement Equipment Setup INPUT OR OUTPUT CAPACITOR Figure 2. Proper Scope Probe Placement for Measuring Input or Output Ripple dc1694bfa... -
Page 4: Parts List
DEMO MANUAL DC1694B PARTS LIST ITEM REFERENCE PART DESCRIPTION MANUFACTURER/PART # Required Circuit Components CAP., ELECTRO., 100µF, 100V CHEMI-CON, EMVY101ARA101MKE0S C2, C3 CAP., X7R, 2.2µF, 100V, 20% 1210 TDK C3225X7R2A225M CAP., X7R, 1.0µF, 100V, 20% 1206 AVX, 12061C105MAT2A CAP., X7R, 0.1µF, 16V, 10% 0402 TDK, C1005X7R1C104K CAP., C0G, 470pF, 50V, 5% 0402... -
Page 5: Schematic Diagram
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. - Page 6 Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions: This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety measures typically found in finished commercial goods.
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