2
dc1883Af
DEMO MANUAL DC1883A
Quick start proceDure
Using short twisted-pair leads for any power connections
and with all loads and power supplies off, refer to Figure 3
for the proper measurement and equipment setup. The
battery/power supply (PS1) should not be connected to
the circuit until it is stated in the following procedure.
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 4), or by using an oscil-
loscope probe tip jack.
1. Jumper, PS1 and LOAD settings to start:
PS1 = OFF
JP1 (RUN) = OFF
JP2 (MODE) = FIXED FREQUENCY
2. With power off, connect the power supply (PS1) as
shown in Figure 3. If accurate current measurements
are desired (for efficiency calculation for example),
then connect an ammeter in series with the supply as
shown. The ammeter is not required, however.
3. Connect a load to V
OUT
, as shown in Figure 3. The load
can be up to 300mA or 6Ω for V
OUT
= 1.8V. 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 5V. Move Jumper JP1 to ON.
5. Verify V
OUT
is ~1.8V.
6. V
IN
can now be varied between 3V and 15V. V
OUT
should
remain in regulation.
7. V
IN
can also be varied down to 2.5V. For V
IN
≤ 3V,
V
OUT
may drop out of regulation, as previously de-
scribed.
8. I
OUT
can also be varied from 0mA to 300mA.
9. For Burst Mode operation, move jumper JP2 to BURST.
See the data sheet for more information.
NOTES:
(1) 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
the data sheet).
(2) To measure no-load input current, remove R4.
V
IN
(V)
3
50
EFFICIENCY (%)
55
65
70
75
100
85
7
11
13
60
90
95
80
5
9
15
dc1883a F01
300mA LOAD
100mA LOAD
V
IN
(V)
3
50
EFFICIENCY (%)
55
65
70
75
100
85
7
11
13
60
90
95
80
5
9
15
dc1883a F02
5mA LOAD
1mA LOAD
10mA LOAD
Figure 1. DC1883A Efficiency in PWM Mode
Figure 2. DC1883A Efficiency in Burst Mode Operation
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