Quick Start Procedure - Linear Technology DC1687A Demo Manual

DEMO MANUAL DC1687A

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 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
and GND terminals (see Figure 4), or by using an oscil-
loscope probe tip jack.
1. Jumper and PS1 settings to start:
PS1 = OFF
JP1 (PWM) = fixed frequency
JP2 (RUN) = ON
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.
100
90
80
70
60
50
5
0
Figure 1. DC1687A Efficiency in PWM Mode
2
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LOAD = 500mA
LOAD = 1A
10 15 20 25 30
V (V)
IN
3. Connect a 500mA load to V
(10Ω for V
current measurement or monitoring is desired.
4. Turn on PS1 and slowly increase voltage until the volt-
age at V
IN
5. Verify V
OUT
6. V can now be varied between 2.7V and 40.0V. I
IN
need to be reduced for V
or V
IN OUT
regulation.
7. Load current (I
I is a function of V
OUT
the data sheet for more information on I
general for V
V > 6V I
IN
8. For operation in Burst Mode operation move Jumper
JP1 to burst. I
See the data sheet for more information.
9. NOTE: If V
the maximum load has not been exceeded, or that V
is not below the minimum value for regulation (see data
sheet)
100
90
80
70
60
50
35 40
0
Figure 2. DC1687A Efficiency in Burst Mode Operation
as shown in Figure 3
OUT
= 5V). Connect an ammeter if accurate
OUT
is 4.0V.
is ~5.0V.
< 4V. V
IN OUT
) can also be varied. The maximum
OUT
and the current limit. Consult
IN
> 3.6V I can be increased to 1A. For
IN OUT
can be increased to 2A.
OUT
is limited in Burst Mode operation.
OUT
drops out of regulation, check to be sure
OUT
5 10 15 20 25
V (V)
IN
may
OUT
should remain in
vs V . In
OUT IN
IN
LOAD = 100mA
LOAD = 200mA
LOAD = 300mA
30 35 40
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