Rainbow Electronics MAX5965B - Manual (Page 31)

MAX5965A/MAX5965B
High-Power, Quad, Monolithic, PSE Controllers
for Power over Ethernet
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Table 13a. Port Status Registers
ADDRESS = 0Ch, 0Dh, 0Eh, 0Fh
SYMBOL BIT R/W
DESCRIPTION
Reserved 7 R Reserved
6 R CLASS_[2]
5 R CLASS_[1] CLASS_
4 R CLASS_[0]
Reserved 3 R Reserved
2 R DET_[2]
1 R DET_[1] DET_ST_
0 R DET_[0]
Table 13b. Detection Result Decoding Chart
DET_ST_[2:0]
(ADDRESS = 0Ch, 0Dh, 0Eh, 0Fh)
DETECTED DESCRIPTION
000 None Detection status unknown
001 DCP Positive DC supply connected at the port (AGND - V OUT_ < 1V)
010 HIGH CAP High capacitance at the port (> 8.5µF)
011 RLOW Low resistance at the port, R PD < 15k Ω
100 DET_OK Detection pass, 15k Ω < R
PD < 33k Ω
101 RHIGH High resistance at the port, R PD > 33k Ω
110 OPEN0 Open port (I < 10µA)
111 DCN Negative DC supply connected to the port (V OUT - V EE < 2V)
Table 13c. Classification Result Decoding
Chart
CLASS_[2:0]
(ADDRESS = 0Ch, 0Dh, 0Eh, 0Fh)
CLASS RESULT
000 Unknown
001 1
010 2
011 3
100 4
101 5
110 0
111 Current limit (> I CILIM )
The port status register (Table 13a) records the results of
the detection and classification at the end of each phase in
three encoding bits each. R0Ch contains the detection
and classification status of port 1. R0Dh corresponds to
port 2, R0Eh corresponds to port 3, and R0Fh corresponds
to port 4. Tables 13b and 13c show the detection/classifi-
cation result decoding charts, respectively. For CLC_EN =
0, the detection result is shown in Table 13b. When
CLC_EN is set high, the MAX5965A/MAX5965B allow valid
detection of high capacitive load of up to 150µF. When 2-event classification is not enabled (ENx_CL6 =
0), the classification status is reported in Table 13c.
When 2-event classification is enabled (ENx_CL6 = 1),
the CLASS_[2:0] bits are set to 000 and the classifica-
tion result is reported in locations R2Ch–R2Fh.
As a protection, when POFF_CL (R17h[3], Table 21) is
set to 1, the MAX5965A/MAX5965B prohibit turning on
power to the port that returns a status 111 after classifi-
cation. A reset sets 0Ch, 0Dh, 0Eh, and 0Fh = 00h.