ACD82224 Datasheet, PDF (18/77 Pages) List of Unclassifed Manufacturers – 24 Ports 10/100 Fast Ethernet Switch

devices as LED drivers. The status display is designed to be flexible to allow the system
designer to choose those indicators appropriate for the specification of the end equipment.
There are two LED control signals, LEDVLD0 and LEDVLD1. They are used to indicate the start
and end of the LED data signal presented on nLED0-nLED3. The LEDCLK signal is a 2.5 MHz
clock signal. The rising edge of LEDCLK should be used to latch the LED data signal into the
LED driver circuitry.
The LED data signals contain Lnk, Xmt, Rcv, Col, Err, Fdx and Spd, which represent Link status,
Transmit status, Receive status, Collision indication, Frame error indication, Full duplex
operation and Operational Speed status respectively. These status signals are sent out
sequentially from port 23 to port 0, once every 50 ms. For details about the timing diagrams of
the LED signals, refer to the chapter of “Timing Description ”
Life Pulse
The ACD82224 will generate Life Pulses at WCHDOG pin once every 800 nsec to indicate
normal operation status. Absence of the Life Pulses is an indication that, the ACD82224 has
encountered some fatal error and needs to be reset. The life pulses are used to reset a watchdog
counter, such that, if the watchdog counter is not reset and has reached a predetermined value,
a system reset signal can be generated to reset the ACD82224.
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