4

dc2046aaf

DEMO MANUAL DC2046A-A

Quick start proceDure

Demonstration circuit 2046A-A is easy to set up to evalu-

ate the performance of the LT4276 in a PoE+ application.

Refer to Figure 8 for proper 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 output voltage ripple by

touching the probe tip and probe ground directly across

scope probe technique.

1. Place test equipment (voltmeter, ammeter, power sup-

plies, and electronic load) as shown in Figure 8.

2. Input supplies:

a. Connect a PoE+ capable PSE with a CAT-5 cable to

the RJ45 connector, J1. See Figure 8.

b.Or,connecta37Vto57Vcapablepowersupply(power

supply in Figure 8) across VPORTP and VPORTN.

c. If evaluating the auxiliary power supply (auxiliary

supply in Figure 8), connect a 37V to 57V capable

power supply across AUX+ to AUX–.

3. Check for the proper output voltage of 3.3V.

4. Once the proper output voltage is confirmed, adjust the

load within the operating range and observe the output

voltage regulation, ripple voltage, efficiency, and other

parameters.

Figure 8. Proper Measurement Equipment Setup

Figure 9. Measurement Input or Output Ripple

Power

Supply

DC1366A

PoE+ PSE

Auxiliary

Supply

Electronic

Load

Scope

Probe

V

V

V

A

A

+

A

-

-

+

+

-

+

+

-

+

-

+

-

+

J1

Ethernet

Cable

-

-