Rainbow Electronics MAX5945 - Manual (Page 28)

MAX5945
In MANUAL mode, R14h works like a pushbutton. Set
the bits high to begin the corresponding routine. The bit
clears after the routine finishes.
When entering AUTO mode, R14h defaults to FFh.
When entering MANUAL mode, R14h defaults to 00h.
When entering SEMI mode, R1h is left unchanged but it
is reset every time the software commands power off
the port. A reset or power-up sets R14h = AAAAAAAAb
where A represents the latched-in state of the AUTO
input prior to the reset.
Setting BCKOFF_ to 1 (Table 18) enables Cadence
timing on each port where the port backs off and waits
2.2s after each failed load discovery detection. The IEEE
802.3af standard requires a PSE that delivers power
through the spare pairs (midspan PSE) to have cadence
timing. A reset sets R14h = 0000XXXX where X is the
logic AND of the MIDSPAN and AUTO input state prior to
a reset. BCKOFF_ can be changed by software at any
time while changes to the MIDSPAN and AUTO input
state during normal operation are ignored.
TSTART[1,0] (Table 19) programs the startup timers,
startup time is the time the port is allowed to be in current
limit during startup. TFAULT_[1,0] programs the fault
time. Fault time is the time allowable for the port to be in
current limit during normal operation. RSTR[1,0] pro-
grams the discharge rate of the TFAULT_ counter and
effectively sets the time the port remains off after an over-
current fault. TDISC[1,0] programs the load disconnect
detection time. The device turns off power to the port if it
fails to provide a minimum power maintenance signal for
longer than the load disconnect detection time (TDISC).
Set the bits in R16h to scale the TSTART, TFAULT, and
TDISC to a multiple of their nominal value specified in
the Electrical Characteristics table. R27h and R28h fur-
Quad Network Power Controller
for Power-Over-LAN
28 ______________________________________________________________________________________
MODE DESCRIPTION
00 Shutdown
01 MANUAL
10 Semi AUTO
11 AUTO
Table 15a. Mode Status
ADDRESS = 13h
SYMBOL BIT R/W
DESCRIPTION
ACD_EN4 7 R/W Enable AC disconnect detection on port 4
ACD_EN3 6 R/W Enable AC disconnect detection on port 3
ACD_EN2 5 R/W Enable AC disconnect detection on port 2
ACD_EN1 4 R/W Enable AC disconnect detection on port 1
DCD_EN4 3 R/W Enable DC disconnect detection on port 4
DCD_EN3 2 R/W Enable DC disconnect detection on port 3
DCD_EN2 1 R/W Enable DC disconnect detection on port 2
DCD_EN1 0 R/W Enable DC disconnect detection on port 1
Table 16. Load Disconnect Detection Enable Register
ADDRESS = 14h
SYMBOL BIT R/W
DESCRIPTION
CLASS_EN4 7 R/W Enable classification on port 4
CLASS_EN3 6 R/W Enable classification on port 3
CLASS_EN4 5 R/W Enable classification on port 2
CLASS_EN3 4 R/W Enable classification on port 1
DET_EN4 3 R/W Enable detection on port 4
DET_EN3 2 R/W Enable detection on port 3
DET_EN2 1 R/W Enable detection on port 2
DET_EN1 0 R/W Enable detection on port 1
Table 17. Detection and Classification Enable Register