Quick Start Procedure - Analog Devices LTC3303A User Manual

User Guide

QUICK START PROCEDURE

Demonstration circuit DC3252A is easy to set up and use to evalu-
ate the performance of the LTC3303A. For the proper measurement
equipment setup, see
NOTE: For accurate V
measure V at the V
IN
at the V SNSE and GND SNSE turrets as shown as VM1 and
OUT
VM2 in Figure 3. When measuring the input or output voltage ripple,
care must be taken to avoid a long ground lead on the oscilloscope
probe. Measure the output voltage ripple by touching the probe
tip directly across the output turrets or to TP1 as shown in
4. TP1 is designed for a 50 Ω coax cable to reduce any high
frequency noise that might couple into the oscilloscope probes.
1. Set the JP1 Jumper to the SKIP position and JP2 to the HI
position.
2. With power off, connect the input power supply to V
If the input EMI filter is required, connect the input power supply
to V EMI.
IN
3. Slowly increase PS1 to 1.0 V. If AM1 reads less than 20 mA,
increase PS1 to 3.3 V. Verify that VM1 reads 3.3 V and VM2
reads 1.2 V.
4. Connect an oscilloscope voltage probe as shown in
in parallel with VM2. Set Channel to AC-coupled, voltage scale
to 20 mV and time base to 10 µs. Observe the V
voltage.
5. Verify that PGOOD turret is above 1 V.
6. Increasing the load by 1 A intervals up to 4 A and record VM1,
VM2, AM1, and AM2 for each interval.
7. Repeat step 6 for PS1 set to 2.5 V and again for PS1 set to 5.0
V.
8. Set the load to a constant 2 A. Remove the oscilloscope voltage
probe from V
OUT
set the voltage scale to 1 V and the time scale to 500 ns/
Division. Trigger on the rising edge of the voltage probe. Using
a tip on the voltage probe, contact the SW node on the pad
of L1. Observe the duty cycle and the period of the switching
waveform (~500 ns).
9. Set the load current to 0.2 A and repeat step 8. Observe that
the switching waveform is now operating in pulse skip mode.
10. Move the jumper on JP2 to LO. Verify that V
and verify that PGOOD is low. Return jumper on JP2 to HI and
verify that VM2 is 1.2 V and verify that PGOOD is above 1 V.
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Figure 3 and follow the procedure below:
, V , and efficiency measurements,
IN OUT
SNSE and GND SNSE turrets, and V
IN
. Place a ground clip on PGND terminal and
OUT
11. If forced continuous or Burst Mode is required, set PS1 to 0
V. Move JP1 to FC or BURST. Repeat steps 3 through 9. In
step 9, observe that the switching waveform is now operating in
forced continuous or Burst Mode.
12. To test the transient response with a base load, add the re-
OUT
quired resistor to produce a minimum load between V
RSNS turrets (RL shown on
resistance is RL plus R8 (100 mΩ).
13. Adjust a signal generator with a 10 ms period, 10% duty cycle,
and an amplitude from 1 V to 2 V to start.
Figure
14. Measure the RSNS voltage to observe the current, V
mΩ. Adjust the amplitude of the pulse to provide the required
transient. Adjust the rising and falling edge of the pulse to
provide the required ramp rate. For more details, see
I
and the optional transient response circuit shown in
and GND.
IN
15. When done, turn off PS1 and Load. Remove all connections to
the demo board.
Figure 4
ripple
OUT
reads 0 V
Figure 3). Note that the total load
= V /100mΩ
OUT RSNS
DC3252A
and
OUT
/100
RSNS
Figure 9
Figure 6.
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