2

DEMO MANUAL DC2134B

Rev. 0

QUICK START PROCEDURE

Demonstration circuit 2134B is easy to set up to evaluate

the performance of the LTC4020. Refer to Figure 1 for

the proper measurement equipment setup and follow the

procedure below.

NOTE: Make sure that the voltage applied to VIN does not

exceed 55V. The combined converter output load current

and battery charging current should not exceed 8A.

1. With power off, connect the input power supply (set

for 0V) to VIN and GND (input return).

2. Connect the converter output load between VOUT and

GND (Initial load: no load).

3. Connect the DVMs to the input and outputs.

4. Turn on the input power supply and slowly increase

to 24V. Check for the proper output voltages, VOUT of

25.2V and BAT of 25.2V.

5. Oncetheproperoutputvoltagesareestablished,adjust

the converter output load within the operating range

(8A maximum) and/or adjust input voltage (15V to

55V) and observe the output voltage regulation, ripple

voltage, efficiency, and other parameters.

NOTE: When measuring the output or input voltage rip-

ple, do not use the long ground lead on the oscilloscope

probe. See Figure 2 for the proper scope probe technique.

Short, stiff leads need to be soldered to the (+) and (–)

terminals of an output capacitor. The probe’s ground ring

needs to touch the (–) lead and the probe tip needs to

touch the (+) lead.

WARNING:

BE CAREFUL WHEN TESTING WITH HIGH VOLT-

AGE. HIGH VOLTAGE CAN RESULT IN AN ELECTRIC

SHOCK IF CARE IS NOT TAKEN.

BATTERIES ARE POTENTIALLY DANGEROUS HIGH

ENERGY SOURCES. IMPROPER CONNECTION,

OVERCHARGE, OR RAPID DISCHARGE COULD

RESULT IN EXPLOSION AND/OR FIRE. PLEASE

READ THE SPECIFICATION/MANUAL OF THE BAT-

TERY BEFORE TEST.

Additional Notes

1. Without a proper battery, BAT output can be open or

connected with other suitable loads for test purposes.

It may be a good practice to add low ESR electrolytic

capacitors to the BAT output (≥1000μF at ≥35V, for

25.2V float voltage).

Note that hese capacitors help simulate the low imped-

ance of a battery and maintain stability of the charge

current loop. They are only needed for test purposes

with electronic or resistive loads, and not needed in

the actual battery application/test (where the BAT load

is a battery).

2. The 0Ω, 2512 jumper (R41) in series with the inductor

can be removed and a wire loop can be added in its

place to facilitate the use of a current probe.

3. BATfloatvoltagecanbeeasilyadjustedwiththeresistor

divider R44/R45. Converter output voltage VOUT can

be adjusted with the resistor divider R9/R11. Adjust/

optimize the loop compensations if necessary.