2
dc1781af
DEMO MANUAL DC1781A
QUICK START PROCEDURE
Demo circuit 1781A is easy to set up to evaluate the
performance of the LT3507A. Refer to Figure 2 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 input or output
voltage ripple by touching the probe tip directly across
the V
IN
or V
OUT
and GND terminals. See Figure 3 for
proper scope probe technique.
1. With power off, connect the input power supply to V
IN
and GND.
2. Turn on the power at the input.
NOTE.
Make sure that the input voltage does not ex-
ceed 36V.
3. Check for the proper output voltages.
NOTE.
If there is no output, temporarily disconnect
the load to make sure that the load is not set too high.
4. Once the proper output voltages are established, adjust
the load within the operating range and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
Figure 1. DC1781A Buck Channel Efficiency at V
IN
= 12V, f = 450kHz
LOAD CURRENT (A)
0.3
0
EFFICIENCY (%)
90
80
70
60
50
40
30
20
10
100
0.6
1.8
2.1
2.4
2.7
0.9
1.2
DC1781A F01
1.5
V
OUT1
= 5.0V
V
OUT1
= 3.3V
V
OUT1
= 1.8V
