LAN91C100FD datasheet(9/67 Pages) SMSC

9 / 67 page

SMSC DS – LAN91C100FD REV. B

Page 9

Rev. 01-20-06

DESCRIPTION OF PIN FUNCTIONS

PQFP/TQFP

PIN NO.

NAME

SYMBOL

BUFFER

TYPE

DESCRIPTION

nChip

Select

Output

nCSOUT

Output. Chip Select provided for mapping of PHY

functions into LAN91C100FD decoded space.

Active on accesses to LAN91C100FD’s eight lower

addresses when the BANK SELECTED is 7.

nReceive

Packet

Discard

nRXDISC

I with

pullup

Input. Used to discard the receive packet being

stored in memory. Assertion of the pin during a

packet reception results in the interruption of

packet reception into memory.

The memory

allocated to the packet and the packet number in

use are freed. The input is driven asynchronously

and

synchronized

internally

the

LAN91C100FD. Pin assertion may take place at

any time during the receive DMA packet.

The

assertion has no effect if there is no packet being

DMAed to memory or if asserted during the last

DMA write to memory.

Works for both MII and

ENDEC. The typical use of nRXDISC is with the

LAN91C100FD in PRMS mode with an external

associative memory use for address filtering.

*Note: The pin must be asserted for a minimum

of 80ns.

RDMAH

Output. Active when the first dword of the address

written

(RCVDMA=1,

RA10-RA4=0,

RA3-

RA2=X).

Buffer Types

Output buffer with 2mA source and 4mA sink

O12

Output buffer with 6mA source and 12mA sink

O16

Output buffer with 8mA source and 16mA sink

O24

Output buffer with 12mA source and 24mA sink

OD16

Open drain buffer with 16mA sink

I/O4

Bidirectional buffer with 2mA source and 4mA sink

I/O24

Bidirectional buffer with 12mA source and 24mA sink

Input buffer with TTL levels

Input buffer with Schmitt Trigger Hysteresis

Iclk

Clock input buffer

DC levels and conditions defined in the DC Electrical Characteristics section.

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