COM20020-5 Datasheet, PDF (5/58 Pages) SMSC Corporation – Universal Local Area Network Controller with 2K x 8 On-Board RAM

DIP PIN
NO.
19
20
21
16,15
17
18
DESCRIPTION OF PIN FUNCTIONS
PLCC PIN
NO.
NAME
SYMBOL
DESCRIPTION
23
nReset in nRESET IN Input. This active low signal issued by the
microcontroller executes a hardware reset.
It is used to activate the internal reset
circuitry within the COM20020-5.
24
nInterrupt nINTR
Output. This active low signal is generated
by the COM20020-5 when an enabled
interrupt condition occurs. nINTR returns to
its inactive state when the interrupt status
condition or the corresponding interrupt
mask bit is reset.
25
nChip Select nCS
Input. This active low signal issued by the
microcontroller selects the COM20020-5 for
an access.
TRANSMISSION MEDIA INTERFACE
19,18
nPulse 2, nPULSE2, Output. In Normal Mode, these active low
nPulse 1
nPULSE1 signals carry the transmit data information,
encoded in pulse format, from the
COM20020-5 to the media driver circuitry.
When the device is in Backplane Mode, the
nPULSE1 signal driver is programmable
(push/pull or open-drain), while the
nPULSE2 signal provides a clock with
frequency of crystal/4. nPULSE1 is
connected to a weak internal pull-up resistor
in backplane mode.
20
Receive In RXIN
Input. This signal carries the receive data
information from the line receiver circuitry to
the COM20020-5.
21
nTransmit nTXEN
Output. This signal is used in Backplane
nEnable
Mode to enable the line drivers for
transmission. The polarity of the signal is
programmable by grounding the nPULSE2
pin. This option is valid only in Backplane
Mode.
5