ON Semiconductor NCP1095GEVB User Manual

NCP1095GEVB

NCP1095 Evaluation Board
User's Manual

IEEE 802.3bt PoE-PD Interface Controller
Board

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EVAL BOARD USER’S MANUAL

General

The NCP1095GEVB board allows easy implementation
and evaluation of a Power-over-Ethernet powered
equipment that is able to operate with an assigned power
level up to 90 W. The evaluation board is based on the PoE
PD Controller NCP1095 (U2) that uses an external
pass-switch (Q1) and sense resistor (R10). The board can
also facilitate the design of proprietary 100 W+
applications.

Figure 1. Operational NCP1095GEVB Showing

Basic Interconnections

The NCP1095GEVB board is designed as a PoE splitter:
having a PoE-enabled Ethernet port (labeled “PoE IN”) as
input and offering the power to a separate connector (J2)
while passing through the data to another Ethernet port
(labeled “E OUT”).

Quick Start Guide

Step 1: Connect the power connections available on
connector J2 (labeled “GND” and “VPP”) to the DC/DC
converter on the system that needs to be powered (cf. black
and red wires in the picture on the left). The DC/DC
converter behind the NCP1095 EVB should be operational
over a 34 V to 57 V voltage range.

Step 2

: Connect the control connection to the DC/DC

converter! It is important that the DC/DC converter or

any significant load is kept off when the pass-switch is
charging the input capacitance.

For a DC-DC converter with an undervoltage (UV or
UVLO) or an active high enable (EN or SHDN
signal on connector J2 could be used (cf. green wire in the
picture on the left). The “PG” signal will be clamped to 18 V
by a zener when the board is powered up. For some DC-DC
converter boards an additional diode in series with the
control connection might be required (cathode connected to
NCP1095 and anode connected to the DC-DC converter).

For a DC-DC converter with an active low enable (EN
SHDN or ON
The “nPG” signal will be pulled up to VPP during the inrush
phase. Always check the voltage rating of the enable,
shutdown or undervoltage pin of the DC-DC converter.

Step 3
on the left) coming from the PSE in the Ethernet connector
J3 labeled “PoE IN”.

If the PSE powers up the system the green PGOOD LED
should be ON.

The status of the remaining LEDs depends on the PSE
being used.

/OFF), the “nPG” signal on P1 could be used.

: Insert the Ethernet cable (cf. blue cable in the picture

), the “PG”

or

© Semiconductor Components Industries, LLC, 2019

June, 2019 − Rev. 0

1 Publication Order Number:

EVBUM2644/D

NCP1095GEVB

Assigned Power

The NCP1095GEVB will request Class 8 during Physical
Layer classification. PDs need to take into account that they
can be underpowered and eventually be assigned to Class 3,
4 or 6.

The state of the NCM and NCL outputs provides
information about the power level that the PSE has assigned
to the NCP1095GEVB during classification. See Table 1 to
determine the assigned power based on the status of the
orange NCM and NCL leds.

Table 1. CLASSIFICATION RESULT

NCM

Led

off off 3 13 W

off on 4 25.5 W

on off 6 51 W

on on 8

NCL

Led

Assigned

Class

Assigned

Power

71.3…90 W

PDs assigned to Class 8 may consume greater than 71.3 W
as long as they guarantee not to exceed the 90 W power limit
at the PSE power interface. Operation beyond 71.3 W is,
however, only possible if additional information is available
to the PD regarding the actual link section DC resistance
between the PSE and the PD.

The application should always operate at or below the
assigned power limit. Failure to do so will result in the PSE
disconnecting the PD!

PSE Categorization

The state of the LCF output provides information
(retrieved during classification) about the type of PSE the
NCP1095GEVB is connected to. See Table 2 to determine
the PSE Type based on the status of the red LCF led.

System Startup

A PD can be underpowered and assigned to Class 3 only.

Therefore the DC/DC converter behind NCP1095GEVB
should not draw more than 13 W during start-up. Eventually
the soft-start setting of the DC/DC converter might need to
be adapted to accomplish this.

Requested Power

As mentioned before, the NCP1095GEVB will request
Class 8 during Physical Layer classification. If a lower Class
or power level is preferred, resistor R8 labeled “CLB”
and/or resistor R7 labeled “CLA” should be changed. See
the NCP1095 datasheet

for the nominal resistance values.

The Class the PD is actually assigned to is always limited
to the requested Class.

Autoclass

The NCP1095GEVB will by default not request
Autoclass during Physical Layer classification. If the PD
should request Autoclass, remove 0E resistor R9 labeled
“acs”.

Maintain Power Signature (MPS)

A PD should draw a minimum amount of current in order
to prevent the PSE from removing power. The load resistor
R15 was added on the bottom side of the board to make sure
the load current is always sufficient and the NCP1095GEVB
remains powered.

Depending on the minimum current the system may draw,
the resistance value of R15 should be increased for the final
design in order not to waste power unnecessarily.

For some systems, the load resistor can even be omitted.

Table 2. PSE TYPE

LCF Led PSE Categorization

off The PSE is categorized according to 802.3af/at

(PSE Type 1 or Type 2)

on The PSE is categorized according to 802.3bt

(PSE Type 3 or Type 4)

The PSE Type determines the MPS timing. It also
indicates to a PD requesting Autoclass whether it makes
sense to go to the maximum power state according to its
assigned Class.

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