QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1031A-C
36V-72VIN, SYNCHRONOUS FORWARD CONVERTER
2
QUICK START PROCEDURE
Demonstration circuit 1031A-C is easy to set up to
evaluate the performance of the LTC3725/LTC3726.
Refer to Figure 1 for proper measurement equipment
setup and follow the procedure below:
NOTE:
When measuring the input or output voltage
ripple, care must be taken to avoid a long ground lead
on the oscilloscope probe. Measure the output (or
input) voltage ripple by touching the probe tip and
probe ground directly across the input or output ca-
pacitor. See Figure 2 for proper scope probe tech-
nique.
1.
Set an input power supply that is capable of 36V to
72V at a current of at least 3.5A to a voltage of 36V.
Then, turn off the supply.
2.
With power off, connect the supply to the input
terVin and –Vin.
a.
Input voltages lower than 36V can keep the con-
verter from turning on due to the undervoltage
lockout feature of the LTC3725/LTC3726.
b.
If efficiency measurements are desired, an am-
meter capable of measuring 3.5Adc can be put
in series with the input supply in order to meas-
ure the DC1031A-C’s input current.
c.
A voltmeter with a capability of measuring at
least 72V can be placed across the input termi-
nals in order to get an accurate input voltage
measurement.
3.
Turn on the power at the input.
NOTE:
Make sure that the input voltage never ex-
ceeds 72V.
4.
Check for the proper output voltage of 5.0V
5.
Turn off the power at the input.
6.
Once the proper output voltages are established,
connect a variable load capable of sinking 20A at
5.0V to the output terVout and –Vout. Set
the current for 0A.
a.
If efficiency measurements are desired, an am-
meter or a resistor current shunt that is capable
of handling at least 20Adc can be put in series
with the output load in order to measure the
DC1031A-C’s output current.
b.
A voltmeter with a capability of measuring at
least 5.0V can be placed across the output ter-
minals in order to get an accurate output voltage
measurement.
7.
Turn on the power at the input.
NOTE:
If there is no output, temporarily disconnect
the load to make sure that the load is not set too
high.
8.
Once the proper output voltage is established, ad-
just the load within the operating range and ob-
serve the output voltage regulation, ripple voltage,
efficiency and other desired parameters.
