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dc1755af
DEMO MANUAL DC1755A
QUICK START PROCEDURE
Demonstration circuit 1755A is easy to set up to evalu-
ate the performance of the LTC3860EUH. Please refer to
Figure 1 for proper measurement equipment setup and
follow the procedure below.
1) With power off, connect the input supply, load and
meters as shown in Figure 1. Preset the load to 0A and
V
IN
supply to be 0V. Place jumpers in the following
positions:
JP1 RUNA
ON
JP2 RUNB
ON
JP3
INT PWR BLK BIAS
ON
2) Adjust the input voltage to be between 6V to 14V. V
OUTA
should 1.5V ± 2%.
V
OUTB
should 1.2V ± 2%.
3) Next, apply 50A load to each output and remeasure
V
OUT
.
4) Once the DC regulation is confirmed, observe the output
voltage ripple, load step response, efficiency and other
parameters.
Note 1. No airflow is required at room temperature with
50A on both outputs. But for ambient temperatures higher
than 30°C, a cooling fan is recommended.
Note 2. Use the BNC connectors labeled V
OUTA
or V
OUTB
to measure the output voltage ripple.
Note 3. Do not apply the load from the VOSA
+
turret to
the VOSA
–
turret or from the VOSB
+
turret to the VOSB
–
turret. These turrets are only intended to monitor the
voltage across COUT3 and COUT13 respectively. Heavy
load currents applied across these turrets may damage
the converter.
DYNAMIC LOAD CIRCUIT (OPTIONAL)
Demonstration circuit 1755A provides a simple load step
circuit consisting of a MOSFET and sense resistor for each
rail. To apply a load step, follow the steps below.
1) Preset the amplitude of a pulse generator to 0.0V and
the duty cycle to 5% or less.
2) Connect the scope to the VOUT BNC connectors for
the rail under test with a coax cable. To monitor the
load step current, connect the scope probe across the
ISTEP
+–
turrets for that rail.
3) Connect the output of the pulse generator to the PULSE
GEN turret for the rail under test and connect the return
to one of the GND turrets.
4) With the converter running, slowly increase the
amplitude of the pulse generator output to provide the
desired load step pulse height. The scaling for the load
step signal is 10mV/A.
