MAX5971BETI+ Maxim Integrated Products, MAX5971BETI+ Datasheet - Page 21

• Manufacturer Part Number: MAX5971BETI+
• Description: Hot Swap & Power Distribution IEEE 802.3af/at PSE Controller
• Manufacturer: Maxim Integrated Products

Specifications of MAX5971BETI+

• Lead Free Status / Rohs Status: Details

Figure 4. LED Code Timing for Overcurrent Fault During Port Power-On
40V (typ). A fault latches into the supply event regis-
ter V
MAX5971B does not power down the port in this case.
Force OSC to V
vate DC load-disconnect monitoring. DCD_EN (R13h[0])
is set to 1 to enable DC load disconnect. If I
current across R
nect threshold, I
turns off port power and sets LD_DISC in the fault event
registers (R06h[4] and R07h[4]) to 1.
The MAX5971B features AC load-disconnect monitoring.
Bypass OSC with a 100nF (Q10% tolerance) external
capacitor to V
matically enable AC disconnect. ACD_EN (R13h[4]) is
set to 1 to enable AC disconnect (the bypass from OSC
to V
is enabled, a blocking diode in series to OUT and an
RC circuit in parallel to the DET diode must be used, as
shown in the typical operating circuit of Figure 16.
The AC disconnect uses an internal triangle-wave gen-
erator to supply the probing signal. Then the resulting
Figure 5. LED Code Timing for Detection Fault Due to High- or Low-Discovery Signature Resistance
EE
EE_UV
PORT POWERED ON
must be in place as well). When AC disconnect
74ms
LED ON
LED
ON
(R0Ah[2] and R0Bh[2], Table 12) but the
EE
EE
SENSE
DCTH
and power or reset the device to auto-
223ms
______________________________________________________________________________________
LED
OFF
and power or reset the device to acti-
INVALID HIGH OR LOW
, for more than t
DC Disconnect Monitoring
AC Disconnect Monitoring
) falls below the DC load-discon-
74ms
LED
ON
LED OFF
223ms
223ms
PORT POWERED DOWN, DUE TO OVERCURRENT FAULT
LED
OFF
Single-Port, 40W, IEEE 802.3af/at,
DISCOVERY SIGNATURE
LED ON
74ms
DISC
74ms
LED
ON
, the device
RSENSE
LED OFF
223ms
223ms
LED
OFF
RESISTANCE DETECTED
(the
SEQUENCE REPEATS
74ms
LED
ON
LED ON
74ms
PSE Controller with I
4V
mode of the output signal probed on DET is 5V below
AGND. If the AC current peak at DET falls below I
for more than t
asserts LD_DISC (R06h[4] and R07h[4]). The AC load-
disconnect threshold (I
AC_TH[2:0] bits (R23h[2:0], see Table 32 for settings).
The MAX5971B includes a multifunction LED driver to
inform the user of the port status. LED is an open-drain,
multifunction output referenced to V
10mA (typ) while driving an external LED. The LED is
turned on when the port is connected to a valid PD and
powered. If the port is not powered or is disconnected,
the LED is off.
For two other conditions, the MAX5971B blinks a code
to communicate the port status. A series of two flashes
indicates an overcurrent fault occurred during port pow-
er-on, and has a timing characteristic detailed by Figure
4. A series of five flashes indicates that during detection
an invalid low or high discovery signature resistance
was detected, and has a timing characteristic detailed
by Figure 5.
P-P
223ms
LED
OFF
LED OFF
amplitude wave is forced on DET. The common
74ms
LED
ON
DISC
LED
OFF
, the device powers down the port and
ACTH
) is programmable using the
PWM and LED Signals
PORT POWERED ON AGAIN
1.4s
LED ON
EE
and can sink
2
ACTH
C
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