3
dc1821bf
DEMO MANUAL DC1821B
Figure 4. Proper Measurement Equipment Setup
Figure 5. Measuring Input or Output Ripple
QUICK START PROCEDURE
Using short twisted pair leads for any power connections
and with all loads and power supplies off, refer to Figure 4
for the proper measurement and equipment setup. The
battery/power supply (PS1) should not be connected to
the circuit until told to do so in the procedure below.
When measuring the input or output voltage ripple, care
must be taken to avoid a long ground lead on the oscil-
loscope 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 5), or by using an oscil-
loscope probe tip jack.
1. Jumper and PS1 settings to start:
PS1:
OFF
JP1:
RUN
ON
JP2:
MODE
FIXED FREQUENCY
2. With power OFF connect the power supply (PS1) as
shown in Figure 4. If accurate current measurements
are desired (for efficiency calculations for example)
connect an ammeter in series with the supply as shown.
The ammeter is not required however.
3. Connect a 500mA load to V
OUT
as shown in Figure 4
(10Ω for V
OUT
= 5V). Connect an ammeter if accurate
current measurement or monitoring is desired.
4. Turn on PS1 and slowly increase voltage until the volt-
age at V
IN
is 4V.
5. Verify V
OUT
is ~5V.
6. V
IN
can now be varied between 2.7V and 40V. I
OUT
may need to be reduced for V
IN
< 4V.
7. Load current (I
OUT
) can also be varied. The maximum
I
OUT
is a function of V
IN
and the current limit. Consult
the data sheet for more information on I
OUT
vs V
IN
. In
general for V
IN
> 5V I
OUT
can be increased to 1A.
8. For operation in Burst Mode operation move Jumper
JP2 to BURST. See the data sheet for more information.
9. NOTE: If V
OUT
drops out of regulation, check to be sure
the maximum load has not been exceeded, or that V
IN
is not below the minimum value for regulation (see
data sheet)
10. NOTE: If V
OUT
is changed to a voltage higher than 5V,
D1 should be removed or the LTC3114-1 could be
damaged.
GND
VIN
