Quick Start Procedure - Linear Technology DC1853A Demo Manual

DEMO MANUAL DC1853A

QUICK START PROCEDURE

Demo circuit 1853A is easy to set up to evaluate the per-
formance of LT3959. Refer to Figure 1 for proper measure-
ment equipment setup and follow the procedure below.
1. With power off, connect the input power supply, load
and meters as shown in Figure 1. Preset the load to 0A,
and V supply to be 0V. Place jumpers in the following
IN
positions.
EN (JP1)
ON
2. Turn on V and increase to 2.5V. Check for proper
IN
output voltages. The output should be regulated at
12V (±3%). The switching frequency should be about
300kHz.
NOTE. If there is no output, or the output is out of spec,
temporarily disconnect the load to make sure that the
load is not set too high.
NOTE. Make sure that the input voltage does not exceed
specification. If higher operating voltage is required,
power components with higher voltage ratings should
be used. The maximum voltage is 40V for the integrated
switch of LT3959.
2
SYNC (JP2)
OFF
3. Once the proper output voltage is established, adjust
Figure 1. Proper Measurement Equipment Setup
NOTE. The demo circuit configures the shutdown volt-
age at 2V, which means that the input voltage can be
dropped to as low as 2V, once it starts up. The startup
voltage is set at 2.5V, and can be adjusted by changing
R1 and R2 values.
NOTE. The output current capability depends on the
input voltage. The output current is up to 0.5A for V
higher than 2V, 1A for V
IN
V higher than 9V.
IN
the input voltage and load within the operating range
and observe the output voltage regulation, ripple volt-
age, efficiency and other parameters. Typical efficiency
curve is shown in Figure 3.
NOTE. When measuring the input or output voltage
ripples, 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 and GND, or V
IN
See Figure 2 for proper scope probe technique.
higher than 5V, and 2A for
and GND terminals.
OUT
dc1853af
IN