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dc2138bfa

DEMO MANUAL DC2138B

QUICK START PROCEDURE

Demo circuit 2138B is easy to set up to evaluate the

performance of the LT8301. Refer to Figure 1 for proper

equipment setup and follow the procedure below.

1. With power off, connect the input power supply to the

board through VIN and GND terminals. Connect the

load to the terminals VOUT+ and VOUT– on the board.

2. Turn on the power at the input. Increase VIN slowly to

10V.

NOTE. Make sure that the input voltage is always within

spec. To operate the board with higher input/output

voltage, input capacitor, output capacitor and output

diode with higher voltage ratings are needed.

NOTE. To run overload tests on the demo board at high

line, additional RC snubber might be needed to make

sure the voltage spike at the switching node is always

less than 65V.

3. Checkfortheproperoutputvoltages.Theoutputshould

be regulated at 5V (±5%).

NOTE. The LT8301 requires very small minimum load

to maintain good output voltage regulation. A Zener

diode is placed on the output to clamp the voltage to

~5V. This Zener is optional, and can be replaced with

a 0.8k resistor.

4. Once the proper output voltage is established, adjust

the input voltage and load current within the operating

range and observe the output voltage regulation, tran-

sient, ripple voltage, efficiency and other parameters.

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 VIN or VOUT capacitor terminals. See Figure 2 for

proper scope probe technique.

5. Figure 5 shows the radiated EMI (Vertical Polarization)

performance with the installation of the optional com-

ponent (C9 560pF). The circuit passed the CISPR 25

Class 5 Peak Limit 5, with less than 2 percentage of

Figure 1. Proper Measurement Equipment Setup