LT3758
DEMO CIRCUIT 1412A
QUICK START GUIDE
LT3758EMSE
FLYBACK CONVERTER
DESCRIPTION
Demonstration
circuit
1412A
features
LT3758EMSE in a 300kHz Flyback converter
circuit, designed for 3.3V output from a 18V to
75V input.
The LT3758EMSE operates over an input range
of 5.5V to 100V, suitable for automotive, tele-
com and industrial applications. It also exhibits
low shutdown quiescent current of 1µA, making
them an ideal fit for battery-operated systems.
Thanks to a novel FBX pin architecture, the
LT3758EMSE can be connected directly to a
divider from either the positive output or the
negative output to ground. It also packs many
popular features such as soft-start, input under-
voltage lockout, adjustable frequency and syn-
chronization in a small 10-lead MSOP package
or a 3mm × 3mm QFN package.
The LT3758EMSE datasheet gives a complete
description of the part, operation and application
information. The datasheet must be read in con-
junction with this quick start guide for demo cir-
cuit 1412A.
Design files for this circuit board are avail-
able. Call the LTC factory.
LT, LTC, LTM and
are registered trademarks of
Linear Technology Corporation. All other trademarks
are the property of their respective owners.
o
Table 1. Performance Summary for 300kHz Flyback Regulator ( TA = 25 C )
PARAMETER
CONDITION
Minimum Input Voltage
Maximum Input Voltage
Output Voltage V
OUT
Maximum Output Current
Typical Switching Frequency
VALUE
18V
75V
3.3V +/-3%
3A
300kHz
QUICK START PROCEDURE
Demonstration circuit 1412A is easy to set up
to evaluate the performance of the
LT3758EMSE. Refer to Figure 1 for proper
measurement equipment setup and follow the
procedure below:
measuring the input or output volt-
age ripple, care must be taken to avoid a long
ground lead on the oscilloscope probe. Meas-
ure the input or output voltage ripple by touch-
ing the probe tip directly across the Vin or
Vout and GND terminals. See Figure 2 for
proper scope probe technique.
1.
Place
2.
With
NOTE.
When
3.
Turn
on the power at the input.
sure that the input voltage does
not exceed the maximum input voltage.
4.
Check
NOTE.
If
NOTE.
Make
for the proper output voltages.
there is no output, temporarily dis-
connect the load to make sure that the load
is not set too high.
Once the proper output voltages are estab-
lished, adjust the loads within the operating
range and observe the output voltage regula-
tion, ripple voltage, efficiency and other pa-
rameters.
JP1 on the ON position.
power off, connect the input power
supply to Vin and GND.
1
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