Analog Devices Linear Technology ADI Power DC3159A Demo Manual page 7

DEMONSTRATION CIRCUIT 3160A KIT
Main VEE PoE Supply
The VEE supply is the main PoE supply connected to the
DC3017A motherboard. Refer to the Quick Start Procedure
for proper connection and Table 2 for appropriate supply
voltage ranges.
Choose a power supply with a current limit set higher
than the maximum allowed output power at each port.
Use the appropriate input supply connections per the
maximum current expected during testing; banana jacks
for up to 15A or the provided Panduit S4-14R lugnuts
for up to 50A, as seen in Figure 6. The lugs are designed
for crimping to 4 AWG welding cable. Use a Thomas &
Betts WT115 crimping tool to crimp the S4-14R lugs to
4 AWG welding cable; do not mash or solder the lugs.
To avoid damage to the motherboard, do not over tighten
the lugs. A torque sufficient to fully compress the split
washer (roughly equivalent to 400 in-oz applied to the ¼-28
hex nut) is sufficient to produce good electrical contact.
Isolation
IEEE 802.3 Ethernet specifications require network seg-
ments (including the analog PoE circuitry) to be electrically
isolated from the chassis ground. The DC3017A moth-
erboard and DC3159A daughter card layouts and high
voltage capacitors provide an isolation barrier between
analog and digital domains. Transformers and layout pro-
vide a galvanic barrier between DGND and AGND on the
DC3159A daughter card. By default, this isolation barrier is
bridged by resistors on the motherboard to allow for evalu-
ation using a single power supply. Remove RISO1 and
RISO2, then provide an external 3.3V supply between VDD
and DGND to evaluate this board as an isolated system.
All RJ45 shields and terminations are connected to
chassis ground. AGND and VEE each connect to chassis
ground with two pairs of 1nF, 2kV capacitors (C6 to C9).
AGND and VEE also connect to DGND each with 10nF,
2kV capacitors (C32 to C33). An optional 0Ω resistor
can be installed at RISO3 to tie the chassis ground to
DGND. Two series 5.1M, 1206 resistors connect between
AGND and DGND for high voltage capacitance discharge.
See Figure 7 for diagram of connections between Analog
and Digital domains, as well as chassis ground on the
DC3017A motherboard.
LED Indicators
The VEE LED (D29) and VDD LED (LED13) indicate if a volt-
age is present at the respective supplies. Verify these LEDs
are off before inserting or removing the daughter card.
Figure 6. Motherboard Power Supply Connections
DEMO MANUAL DC3160A
Rev. 0
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