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dc1480af
DEMO MANUAL DC1480A
QUICK START PROCEDURE
Demonstration circuit 1480A is easy to set up to evaluate
the performance of the LTC3865EUH-1. Refer to Figure 1
for the proper measurement equipment setup and follow
the procedure below:
Jumper positions:
JP1 (MODE): PS
JP2, JP3 (RUN1/RUN2): ON
1. With power off, connect the input power supply to V
IN
(4.5V to 14V) and GND (input return).
2. Connect the load #1 between V
OUT1
and GND (Initial
load: no load); connect the load #2 between V
OUT2
and
GND (Initial load: no load).
3. Connect the DVMs to the input and outputs.
4. Turn on the input power supply and check for the proper
output voltages. With current VID pin setting, V
OUT1
should be 3.3V ±1%; V
OUT2
should be 1.8V ±1%.
5. Once the proper output voltages are established,
adjust the loads within the operating range and observe
the output voltage regulation, ripple voltage and other
parameters.
6. If necessary, change the resistor options on VID pins
for other output voltages according to Table 1.
Note 1. When measuring the output or input voltage ripple, do not use the
long ground lead on the oscilloscope probe. See Figure 2 for the proper
scope probe technique. Short, stiff leads need to be soldered to the (+)
and (–) terminals of an output capacitor. The probe’s ground ring needs to
touch the (–) lead and the probe tip needs to touch the (+) lead.
Note 2. To accurately measure the output voltages and efficiency, measure
V
OUT1
and V
OUT2
on output capacitors C
OUT2
and C
OUT4
directly.
OUTPUT VOLTAGE PROGRAMMING
The output voltages of both channels can be programmed
to preset values. There are two VID pins for each channel:
VID11, VID12 for V
OUT1
, and VID21, VID22 for V
OUT2
. See
Table 1 for details.
Table 1. Output Voltage Programming
VID11/VID21
VID12/VID22
V
OUT1
/V
OUT2
(V)
INTV
CC
INTV
CC
5V (V
IN
≥ 5V)
INTV
CC
FLOAT
3.3V
INTV
CC
GND
2.5V
FLOAT
INTV
CC
1.8V
FLOAT
FLOAT
0.6 or External Divider
FLOAT
GND
1.5V
GND
INTV
CC
1.2V
GND
FLOAT
1V
GND
GND
1.1V