Linear Technology DC2397A Demo Manual page 2

DEMO MANUAL DC2397A
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
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 5), or by using an oscil-
loscope probe tip jack.
1. Jumper and PS1 settings to start:
PS1:
JP1: MODE
JP2: VS1
JP3: VS2
JP4: MPPC
JP5: RUN
JP6: EXTV
CC
2. With power OFF connect the power supply (PS1) as
shown in Figure 4. If accurate current measurements
are desired (for efficiency calculation for example)
then connect ammeters in series with supplies as
shown. The ammeters are not required however.
100
90
80
70
60
50
40
30
20
10
0
1.0E-04 1.0E-03
LOAD CURRENT (A)
V = 5V, PWM MODE
IN
V = 5V, Burst Mode OPERATION
IN
V = 24V, Burst Mode OPERATION
IN
V = 24V, PWM MODE
IN
Figure 1: DC2397A Typical Efficiency vs Load. V
2
or V
IN
OFF
FIXED FREQ
V
CC
V
CC
OFF
ON
INT
1.0E-02 1.0E-01 1.0E+00
DC2397A F01
= 12V.
OUT
3. Connect a 50mA load (240Ω) to V
Figure 4.
4. Turn on PS1 and slowly increase the voltage until
the voltage at V
5. Verify V
OUT
6. V can now be varied between 2.4V and 25V. The
IN
load may need to be reduced for V
to remain in regulation.
OUT
7. The load can be varied. The maximum load is a
function of V
the data sheet for more information on output cur-
rent vs V .
IN
8. V can be varied by setting jumpers JP2 and JP3
OUT
in accordance with the "V
RATION" table on the front of the DC2397A demo
board.
9. For operation in Burst Mode, move jumper JP1 to
"Burst Mode" position. See the data sheet for more
information on Burst Mode operation.
10. For operation with V
JP6 to "EXT".
NOTE: If V
OUT
sure the maximum load has not been exceeded, and
that V is not below the minimum value for regula-
IN
tion (see data sheet).
V : 500mV/DIV
OUT
I : 200mA/DIV
OUT
Figure 2. DC2397A Step Load Response. V
V = 12V, Load Step is from 100mA to 400mA.
OUT
OUT
is 3V.
IN
is ~12V.
IN
and the device current limit. Consult
IN
JUMPER CONFIGU-
OUT
powered from V
CC
drops out of regulation, check to be
200μs/DIV
IN
as shown in
< 3V for V
OUT
, move
OUT
= 12V,
dc2397af