Rainbow Electronics MAX5965B - Manual (Page 34)

MAX5965A/MAX5965B
High-Power, Quad, Monolithic, PSE Controllers
for Power over Ethernet
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Setting DET_EN_/CLASS_EN_ to 1 (Table 18) enables
load detection/classification, respectively. Detection
always has priority over classification. To perform clas-
sification without detection, set the DET_EN_ bit low
and CLASS_EN_ bit high.
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 semi or manual modes, R14h defaults to 00h.
A reset or power-up sets R14h = AAAAAAAAb where A
represents the latched-in state of the AUTO input prior
to the reset.
Table 18. Detection and Classification 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_EN2 5 R/W Enable classification on port 2
CLASS_EN1 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 19. Backoff and High-Power Enable Register
ADDRESS = 15h
SYMBOL BIT R/W
DESCRIPTION
EN_HP_ALL 7 R/W High-power detection enabled
EN_HP_CL6 6 R/W Class 6 PD high-power enabled
EN_HP_CL5 5 R/W Class 5 PD high-power enabled
EN_HP_CL4 4 R/W Class 4 PD high-power enabled
BCKOFF4 3 R/W Enable cadence timing on port 4
BCKOFF3 2 R/W Enable cadence timing on port 3
BCKOFF2 1 R/W Enable cadence timing on port 2
BCKOFF1 0 R/W Enable cadence timing on port 1
EN_HP_CL, EN_HP_ALL together with CL_DISC
(R17h[2]) and ENx_CL6 (R1Ch[7:4]) are used to program
the high-power mode. See Table 3 for details.
Setting BCKOFF_ to 1 (Table 19) enables cadence tim-
ing 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 or power-up sets R15h = 0000XXXXb where ‘X’
is the logic AND of the MIDSPAN and AUTO inputs.