Linear Technology DC1788B Demo Manual page 4

DEMO MANUAL DC1788B
Dc1788B-a quick start proceDure
NOTE: Handle the DC1788B-A by the edge of the board.
Power over Ethernet Input
1. Refer to Figure 1 to evaluate the DC1788B-A with a
DC/DC converter. If a resistive load is used to evaluate the
DC1788B-A, connect the load by hand between VOUT+
and VOUT– after the LED (D3) is lit. It is recommended
to disconnect the resistive load before powering down
the DC1788B-A, so at the next turn on the load is discon-
nected. If the load is not connected and disconnected
by hand properly, the PD may not power on. Contact
field applications engineers for further details.
2. Default class select shunt positions are at JP1 and JP2
on the DC1788B-A board. In this configuration, any PSE
will turn on this PD. Choose a power level from Table 3
and select the corresponding shunt positions.
Figure 1. Setup Diagram for the DC1788B-A with a DC/DC Converter, a Microprocessor, and an LTPoE ++ PSE
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3. Check the power delivery capability of the LTPoE ++
PSE to ensure it can power the PD and the load. Do
not select a jumper position corresponding to a higher
power level than the LTPoE ++ PSE can provide. Oth-
erwise, the LTPoE ++ PSE will not turn on the PD after
classification.
4. Connect the output of the PSE to the RJ45 connector
(J1) on the DC1788B-A board with a CAT5e or CAT6
Ethernet cable.
5. After connection has been established, verify that the
LED (D3) is lit. This indicates the PSE has successfully
detected and powered the PD
dc1788bfa