Rainbow Electronics MAX5971B - Manual (Page 32)

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MAX5971B
Single-Port, 40W, IEEE 802.3af/at,
PSE Controller with I 2 C
Disconnect Enable Register (R13h)
The disconnect enable register (R13h, Table 20) is used
to enable AC and DC load-disconnect detection. On
power-up or after a reset condition, this register is reset to
a default value of 000x to 000x, where the status latched
in from the OSC input determines if AC or DC disconnect
is set (see the AC/DC Disconnect Monitoring sections
for details). Setting DCD_EN (R13h[0]) to 1 enables the
DC load-disconnect detection feature. Setting ACD_EN
(R13h[4]) to 1 enables the AC load-disconnect feature.
If enabled, the load-disconnect detection starts during
power mode and after startup when the PGOOD bit
(R10h[4], Table 16) goes high.
Detection and Classification
Enable Register (R14h)
The detection and classification enable register (R14h,
Table 21) is used to enable detection and classification
routines for the port. On a power-up or after a reset con-
dition, this register is set to a default value of FFh (which
corresponds to the default auto mode). Setting DET_EN
(R14h[0]) and CLASS_EN (R14h[4]) to 1 enables load
detection and classification, respectively. Detection
always has priority over classification. For classifica-
tion without detection, set the DET_EN bit to 0 and the
CLASS_EN bit to 1.
When entering auto mode, R14h defaults to FFh. When
entering semi or manual modes, R14h defaults to 00h.
In manual mode, R14h works like a pushbutton. Set the
bits high to launch the corresponding routine. The bit
then clears after one complete detection or classification
cycle finishes.
Table 20. Disconnect Enable Register
Table 21. Detection And Classification Enable Register
ADDRESS = 13h
DESCRIPTION
SYMBOL BIT NO. TYPE
Reserved 7 — Reserved
Reserved 6 — Reserved
Reserved 5 — Reserved
ACD_EN 4 R/W Enable AC disconnect detection on the port
Reserved 3 — Reserved
Reserved 2 — Reserved
Reserved 1 — Reserved
DCD_EN 0 R/W Enable DC disconnect detection on the port
ADDRESS = 14h
DESCRIPTION
SYMBOL BIT NO. TYPE
Reserved 7 — Reserved
Reserved 6 — Reserved
Reserved 5 — Reserved
CLASS_EN 4 R/W Enable classification on the port
Reserved 3 — Reserved
Reserved 2 — Reserved
Reserved 1 — Reserved
DET_EN 0 R/W Enable detection on the port