MAX5965A/MAX5965B
High-Power, Quad, Monolithic, PSE Controllers
for Power over Ethernet
36 ______________________________________________________________________________________
Setting CL_DISC to 1 (Table 21) enables port over class
current protection, where the MAX5965A/MAX5965B
scales down the overcurrent limit (V
FLT_LIM
) according
to the port classification status. This feature provides
protection to the system against PDs that violate their
maximum class current allowance.
The MAX5965 is programmed to switch to a high-power
configuration and HP_TIME is low, the higher current set-
ting is enabled only after a successful startup so that the
PD powers up as a normal 15W device. If HP_TIME is set
together with EN_HP_ALL, the higher current setting will
be active before startup. For Classes 4, 5, and 6, the
corresponding enable bit in register R15h must be set
together with EN_HP_ALL. In any other cases, the cur-
rent level defaults to Class 0.
CL_DISC, together with EN_HP_CL_ (R15h[6:4]),
EN_HP_ALL (R15h[7]), and ENx_CL6 (R1Ch[7:4]) are
used to program the high-power mode. See Table 3 for
details.
Setting OUT_ISO high (Table 21), forces DET_ to a
high-impedance state.
A reset sets R17h = 0xC0.
Table 21. Miscellaneous Configurations 1 Register
ADDRESS = 17h
SYMBOL BIT R/W
DESCRIPTION
INT_EN 7 R/W A logic-high enables INT functionality
RSTR_EN 6 R/W A logic-high enables the autorestart protection time off (as set by the RSTR[1:0] bits)
Reserved 5 — Reserved
Reserved 4 — Reserved
POFF_CL 3 R
A logic-high prevents power-up after a classification failure (I > 50mA, valid only in AUTO
mode)
CL_DISC 2 R/W
A logic-high enables reduced current-limit voltage threshold (V
FLT_LIM
) according to port
classification result
Table 22. Power-Enable Pushbuttons Register
ADDRESS = 19h
SYMBOL BIT R/W
DESCRIPTION
PWR_OFF4 7 W A logic-high powers off port 4
PWR_OFF3 6 W A logic-high powers off port 3
PWR_OFF2 5 W A logic-high powers off port 2
PWR_OFF1 4 W A logic-high powers off port 1
PWR_ON4 3 W A logic-high powers on port 4
PWR_ON3 2 W A logic-high powers on port 3
PWR_ON2 1 W A logic-high powers on port 2
PWR_ON1 0 W A logic-high powers on port 1
Power-enable pushbutton for semi and manual modes
is found in Table 22. Setting PWR_ON_ to 1 turns on
power to the corresponding port. Setting PWR_OFF_ to
1 turns off power to the port. PWR_ON_ is ignored when
the port is already powered and during shutdown.
PWR_OFF_ is ignored when the port is already off and
during shutdown. After execution, the bits reset to 0.
During detection or classification, if PWR_ON_ goes
high, the MAX5965A/MAX5965B gracefully terminate
the current operation and turn on power to the port. The
MAX5965A/MAX5965B ignore the PWR_ON_ in auto
mode. A reset sets R19h = 00h.
(20 paginas)
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