2
dc1881af
DEMO MANUAL DC1881A
QUICK START PROCEDURE
Figure 1. Proper Measurement Equipment Setup
Demonstration circuit 1881A is easy to set up to evaluate
the performance of the LTC3789. Refer to Figure 1 for
the proper measurement equipment setup and follow the
procedure below:
1. With power off, connect the input power supply to V
IN
(6V to 36V) and GND (input return).
2. Connect the 12V output load between V
OUT
and GND
(Initial load: no load).
3. Connect the DVMs to the input and outputs.
4. Turn on the input power supply and check for the proper
output voltages. V
OUT
should be 12V ±2%.
5. Once the proper output voltages are established, ad-
just the loads within the operating range and observe
the output voltage regulation, ripple voltage and other
parameters.
Note: When measuring the output or input voltage ripple,
do not use the long ground lead on the oscilloscope probe.
See Figure 2 for the proper scope probe technique. Short,
stiff leads need to be soldered to the (+) and (–) terminals
of an output capacitor. The probe’s ground ring needs to
touch the (–) lead and the probe tip needs to touch the
(+) lead.
Additional Notes:
1. Usually, the worst case efficiency at full load is at 6V
IN
.
The board can deliver more output power at higher V
IN
.
2. R2 is needed for additional/constant output current
limit only.