2
dc2392af
DEMO MANUAL DC2392A
Quick start proceDure
Demonstration circuit 2392 is easy to set up to evaluate
the performance of the LTC7860. Refer to Figure 1 for
proper measurement equipment setup and follow the
procedure below:
NOTE: When measuring the output voltage ripple, care must
be taken to avoid a long ground lead on the oscilloscope
probe. Measure the output voltage ripple by touching the
probe tip and ground ring directly across the last output
capacitor as shown in Figure 1.
1. Set an input power supply that is capable of 7V to
100V to 10V. Then turn off the supply.
2. With power off, connect the supply to the input termi-
nals +V
IN
and –V
IN
.
a. Input Voltages lower than 7V can keep the converter
from turning on due to the undervoltage lockout feature
of the LTC7860.
b. A voltmeter with a capability of measuring at least 100V
can be placed across the input terminals 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 exceeds
100V.
4. Check for the proper output voltage of 10V. Turn off
the power at the input.
5. Once the proper output voltage is established, connect
a variable load capable of sinking 10A at 34V to the
output terV
OUT
and –V
OUT
. Set the current for
0A.
a. A Voltmeter with a capability of measuring at least 36V
can be placed across the output terminals in order to
get an accurate output voltage measurement.
6. 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.
7. Once the proper output voltage is again established,
adjust the load and/or input within the operating range
up to 33V
IN
and observe the output voltage and other
desired parameters.
8. Now apply an input between 35V and 100V and ob-
serve the output voltage and fault timer operation.
9. If desired, you may apply input transient profiles in
the range of 0V
IN
to 100V
IN
and observe the output
to illustrate operation of the circuit to prevent input
surges from reaching the output.
10. The output limit voltage can be set in accordance
with the feedback notes on the schematic. The first
line shows the complete formula. The second line is
simplified for the use of a 2:1 divider as shown on the
schematic.