Datasheet

MAX5974A Evaluation Kit
Evaluates: MAX5974A
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PD Classification Signature
The EV kit is configured for a Class 4 (12.95W to 25.5W)
PD classification by resistor R4. To reconfigure the PD
classification, replace surface-mount 0805 resistor R4.
Table 1 lists the PD classification options.
Wall-Adapter Power Source (PWR+, PWR-)
The EV kit can also accept power from a wall-adapter DC
power source applied at the PWR+ and PWR- PCB pads.
The wall-adapter power-source operating-voltage range
must be within +37V to +57V for the EV kit.
When the wall-adapter power source is above +30V, it
takes precedence over the PSE source. Once the wall-
adapter power source is detected, the MAX5969B’s
internal isolation switch disconnects VSS from RTN.
The wall-adapter power is supplied to VDD (through
diode D7) and RTN. Once it takes over, the classification
process is disabled. Resistors R27 and R28 are available
for adjusting the EV kit wall-adapter voltage for disabling
the PSE source.
When the wall-adapter power source is below +21V, the
PSE provides power through the device’s RTN. Diode
D7 prevents the PSE from back-driving the wall-adapter
power source when it is below +7V.
Ethernet Data-Signal Interfacing
The EV kit features a modular RJ45 jack (J1) to interface
with the Ethernet data signals. J1 is provided for interfac-
ing the EV kit with the Ethernet data signals only. Refer to
the RJ45 MagJack data sheet on the Bel Fuse website
prior to interfacing the EV kit’s J1 modular RJ45 jack with
the Ethernet data signals.
Table 1. PD Classification Signature
Selection
CLASS
MAXIMUM POWER
USED BY PD (W)
RESISTOR R4 (I)
0 0.44 to 12.95 615
1 0.44 to 3.84 117
2 3.84 to 6.49 66.5
3 6.49 to 12.95 43.7
4 12.95 to 25.5 30.9
5 > 25.5 22.6