MAX5952_10 Datasheet, PDF (16/50 Pages) Maxim Integrated Products – High-Power, Quad, PSE Controller for Power-Over-Ethernet

High-Power, Quad, PSE Controller
for Power-Over-Ethernet
Operation Modes
The MAX5952 contains four independent, but identical
state machines to provide reliable and real-time control
of the four network ports. Each state machine has four
operating modes: auto mode, semi-auto mode, manual,
and shutdown. Auto mode allows the device to operate
automatically without any software supervision. Semi-
auto mode, upon request, continuously detects and
classifies a device connected to a port but does not
power up that port until instructed by software. Manual
mode allows total software control of the device and is
useful in system diagnostics. Shutdown mode termi-
nates all activities and securely turns off power to the
ports.
Switching between auto, semi, or manual mode does
not interfere with the operation of the port. When the
port is set into shutdown mode, all the port operations
are immediately stopped and the port remains idle until
shutdown is exited.
Automatic (Auto) Mode
Enter automatic (auto) mode by forcing the AUTO input
high prior to a reset, or by setting R12h[P_M1,P_M0] to
[1,1] during normal operation (see Tables 16 and 16a).
In auto mode, the MAX5952 performs detection, classi-
fication, and powers up the port automatically once a
valid PD is detected at the port. If a valid PD is not con-
nected at the port, the MAX5952 repeats the detection
routine continuously until a valid PD is connected.
Going into auto mode, the DET_EN and CLASS_EN bits
are set to high and stay high unless changed by soft-
ware. Using software to set DET_EN and/or CLASS_EN
low causes the MAX5952 to skip detection and/or clas-
sification. As a protection, disabling the detection rou-
tine in auto mode does not allow the corresponding port
to power up, unless the DET_BY (R23H[4]) is set to 1.
The AUTO status is latched into the register only dur-
ing a reset. Any changes to the AUTO input after reset
are ignored.
Semi-Automatic (Semi-Auto) Mode
Enter semi-auto mode by setting R12h[P_M1,P_M0] to
[1,0] during normal operation (see Tables 16 and 16a).
In semi-auto mode, the MAX5952, upon request, per-
forms detection and/or classification repeatedly but
does not power up the port(s), regardless of the status
of the port connection.
Setting R19h[PWR_ON_] (Table 22) high immediately
terminates detection/classification routines and turns on
power to the port(s).
R14h[DET_EN_, CLASS_EN_] default to low in semi-auto
mode. Use software to set R14h[DET_EN_, CLASS_EN_]
to high to start the detection and/or classification rou-
tines. R14h[DET_EN_, CLASS_EN_] are reset every time
the software commands a power off of the port (either
through reset or PWR_OFF). In any other case, the status
of the bits is left unchanged (including when the state
machine turns off the power because a load disconnect
or a fault condition is encountered).
Manual Mode
Enter manual mode by setting R12h[P_M1,P_M0] to [0,1]
during normal operation (see Tables 16 and 16a).
Manual mode allows the software to dictate any
sequence of operation. Write a 1 to both R14h[DET_EN_]
and R14h[CLASS_EN_] to start detection and classifica-
tion operations, respectively, and in that priority order.
After execution, the command is cleared from the regis-
ter(s). PWR_ON_ has highest priority. Setting PWR_ON_
high at any time causes the device to immediately enter
the powered mode. Setting DET_EN and CLASS_EN
high at the same time causes detection to be performed
first. Once in the powered state, the device ignores
DET_EN_ or CLASS_EN_ commands.
When switching to manual mode from another mode,
DET_EN_, CLASS_EN_ default to low. These bits
become pushbutton rather than configuration bits (i.e.,
writing ones to these bits while in manual mode com-
mands the device to execute one cycle of detection
and/or classification. The bits are reset back to zeros at
the end of the execution).
Shutdown Mode
Enter shutdown mode by forcing the AUTO input low
prior to a reset, or by setting R12h[P_M1,P_M0] to [0,0]
during normal operation (see Tables 16 and 16a). Putting
the MAX5952 into shutdown mode immediately turns off
power and halts all operations to the corresponding port.
The event and status bits of the affected port(s) are also
cleared. In shutdown mode, the DET_EN_, CLASS_EN_
and PWR_ON_ commands are ignored.
In shutdown mode, the serial interface operates normally.
PD Detection
When PD detection is activated, the MAX5952 probes
the output for a valid PD. After each detection cycle,
the device sets the DET_END_ bit R04h/05h[3:0] high
and reports the detection results in the status registers
R0Ch[2:0], R0Dh[2:0], R0Eh[2:0], and R0Fh[2:0]. The
DET_END_ bit is reset to low when read through R05h
or after a port reset.
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