MAX5922
+48V, Single-Port Network Power Switch
For Power-Over-LAN
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PD Classification Mode
(PD Classification)
Following a valid PD detection, and if the CLASS pin is
high, the MAX5922 enters the PD classification mode. If
the CLASS pin is low, the PD classification mode is
skipped and the MAX5922 goes directly from PD
detection to the power mode. During the PD classifica-
tion mode, the MAX5922 forces a probe voltage (17.5V)
at the OUT pin and measures the current out of this pin.
The measured current determines the class of the PD.
The classification results are reported at the classifica-
tion logic outputs CL0, CL1, CL2. Table 2 shows the
classification threshold limits and the corresponding
logic outputs CL0, CL1, and CL2.
Connect an external 150Ω ±1% resistor (R
RCL
) from
RCL to IN to set the classification current reference. If
the PD classification function is not used, RCL can be
left floating. For the MAX5922B/MAX5922C, the
DET_DIS pin must be connected low to enable the
classification phase. If DET_DIS is connected high, the
classification phase is disabled regardless of the state
of the CLASS pin. After the classification phase, the
MAX5922 enters power-up.
Power-Up Mode
After the PD is successfully detected and classified, the
MAX5922 enters power-up mode. During this mode,
the MAX5922 gradually turns on the integrated N-chan-
nel MOSFET. To minimize EMI, the MAX5922 limits the
Table 2. PD Classification Threshold Limits
or CLASS pin connected low.
