MAX5940AESA View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

MAX5940AESA

IEEE 802.3af PD Interface Controller For Power-Over-Ethernet

Maxim Integrated 

IEEE 802.3af PD Interface Controller

For Power-Over-Ethernet

Typical Application Circuits (continued)

Application Circuit 2

Diode D1 prevents the power-over-ethernet to back

drive the wall adapter. Whenever the wall adapter

power is greater than (VD3 + approximately 2V), the

GATE is pulled low to pinch off the power-over-ethernet.

The wall adapter power pollutes the discovery signa-

ture, preventing PSE from detecting this PD.

GND

60V

-48V

WALL

ADAPTER

SUPPLY

RDISC

25.5kΩ

68nF

RCL

VEE

GATE

1 UVLO

8

GND

MAX5940B

2

MAX5940D

RCLASS

PGOOD

7

PGOOD

3 GATE

6

PGOOD

4 VEE

OUT 5

CGATE

D1

D3

100kΩ

PS2701A-1

GATE

PGOOD

VEE

CMPT3904

2.0kΩ

CMPT3904

DC-DC CONVERTER

V+

COUT

MAX5014

VREG

GND

SS_SHDN

LOAD

Figure 5. Adding Wall Adapter Input Supply (Wall Adapter Supply Takes Precedence Over Power-Over-Ethernet)

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