Performance Summary; Quick Start Procedure - Linear Technology DC1848A Manual

DEMO MANUAL DC1848A

performance summary

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0 0.5 1 1.5 2
LOAD CURRENT (A)
Figure 1. LT3976 Efficiency vs Load Current

Quick start proceDure

Demonstration circuit 1848A is easy to set up to evalu-
ate the performance of the LT3976. Refer to Figure 3 for
proper measurement equipment setup and follow the
procedure below:
NOTE: When measuring the input or output voltage ripple,
care must be taken to avoid a long ground lead on the
oscilloscope probe. Measure the input or output voltage
ripple by touching the probe tip directly across the V
or V and GND terminals. See Figure 4 for the proper
OUT
scope technique.
1. Place JP1 on the ON position.
2. Place JP2 on the RT FREQ position.
3. With power off, connect the input power supply to V
and GND. Make sure that the input voltage does not
exceed 40V.
2
V = 12V
IN
V = 3.3V
OUT
f = 400kHz
S
2.5 3 3.5 4 4.5 5
DC1848A F01
Figure 2. LT3976 Demo Board EMI Performance,
Switching Frequency 400kHz
4. With power off, connect load from V
5. Turn on the power at the input.
6. Check for the proper output voltage (3.3V).
NOTE: If there is no output, temporarily disconnect the
load to make sure that the load is not set too high or
is shorted.
7. Once the proper output voltage is established, adjust
IN
the load within the operating ranges and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
8. An external clock can be added to the SYNC terminal
when SYNC function is used (JP2 on the SYNC posi-
IN
tion). Please make sure that the SYNC frequency is at
least 20% higher than the set switching frequency. See
the data sheet section Synchronization.
to GND.
OUT
dc1848af