TPS2388 Datasheet, PDF (52/82 Pages) Texas Instruments – IEEE 802.3at 8-Channel Power-over-Ethernet PSE Controller

TPS2388
SLUSC25A – FEBRUARY 2015 – REVISED AUGUST 2017
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8.6.27 IEEE Power Enable Register
COMMAND = 23h with 1 Data Byte, Write Only
Used to do a port(s) turn on during semiauto mode. This command is ignored if in manual mode. Note that if at
completion of this command the addressed port is not turned on, the corresponding bits in the Detect/Class
Enable register (register 14h) are being set, which means that detection and classification are performed
continuously, as long as the class and detect enable bits are kept set.
Writing a 1 at a TmPONn bit will turn on the associated port but only if the IEEE802.3 TPON timing specification
can be met. TPON specification is the time from the completion of a valid detection cycle to port turn ON.
If TPON specification cannot be met, a new detection cycle is restarted, followed by a classification cycle, at the
end of which the port is turned on, but only if a valid detection and classification is returned. For this case, there
is no additional attempt to turn on the port until this push button is reasserted.
Note that a port turn on will be performed only after both its current detection and classification cycle are
completed
Note that writing a 1 at T1PONn and T2PONn of same port during the same write operation is interpreted as a
T1PONn.
The corresponding PGCn and PECn bits of Power Event register will also be set depending on the result, while
the CLSCn and DETCn bits of Detection Event register will be set based on the result and the CLCHE and
DECHE bits in the General Mask register.
Also note that t_OVLD, t_LIM, t_START, and disconnect events are prioritary over the power on command. During t_OVLD,
t_LIM, or t_START cool down cycle, any port turn on using IEEE Power Enable command will be ignored and the port
will be kept off.
Figure 46. IEEE Power Enable Register Format
7
6
5
4
3
Type 2 IEEE Power Enable Pushbutton
T2PON4
T2PON3
T2PON2
T2PON1
T1PON4
W-0
W-0
W-0
W-0
W-0
LEGEND: R/W = Read/Write; R = Read only; W = Write only; -n = value after reset
2
1
Type 1 IEEE Power Enable Pushbutton
T1PON3
T1PON2
W-0
W-0
0
T1PON1
W-0
Table 25. IEEE Power Enable Register Field Descriptions
Bit Field
Type Reset Description
7–4 T2PON4–T2PON1 W
0 If class 4 is detected during the first event classification, a second event classification is
performed. If the last detection result is not valid or last classification result yields “over
current” or is different from the first classification event result, the port is not turned on, and
the STRTn bit in Start/Ilim Event register is set, while the corresponding fault code in the
Power-on Fault register is written.
When power-on is complete and if class 4 has been detected, the corresponding PoEPn bit
in PoE Plus register is set and the value of the corresponding Police Configuration register is
set to 640 mA (08h code). This is done within 5 ms of completion of inrush.
3–0 T1PON4–T1PON1 W
0 Indicates only a single-event classification is performed, even if a class 4 PD is detected.
If the last detection result is not valid or last classification result yields “over current”, the port
is not turned on, and the STRTn bit in Start/Ilim Event register is set, while the
corresponding fault code in the Power-on Fault register is written.
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