MEA-224 Zarlink Semiconductor, Inc., MEA-224 Datasheet - Page 8

• Manufacturer Part Number: MEA-224
• Description: 4-Port, Layer 2 Fast Ethernet Access Controller
• Manufacturer: Zarlink Semiconductor, Inc.

XpressFlow-2001 Series –
Ethernet Switch Chip-set
4. FUNCTIONAL DESCRIPTION
4.1 Local Memory (Local Buffer Memory) Interface
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4.1.1 Pin Description
©
1997
Use industry standard Synchronous Burst Mode SRAM up to 1M bytes
Provides 4 individual Byte Write Enable controls ( L_BWE[3:0]# )
Provides separate Read and Write Chip Selects ( L_OE[3:0]# and L_WE[3:0]# ) for each memory chip
Supports back to back Read or Write operations across memory chips
Note:
32k x 32, 64k x 32, 128k x 32, or 256k x 32
L_D[31:0]
L_A[18:2]
L_A[19] /
L_OE[3]#
L_OE[2:0]#
L_WE[3:0]#
L_BWE[3:0]#
L_ADSC#
L_CLK
(57(; (7:25.6
Symbol
These pins have weak internal pull up resistors (50k to 100k Ohms each).
P R E L I M I N A R Y
I/O-TS
CMOS
Output
CMOS
Output
CMOS
Output
CMOS
Output
CMOS
Output
CMOS
Output
CMOS
Output
Type
TTL
Name & Functions
Local Memory Data Bus Bit [31:0] – a 32-bit synchronous data bus.
Local Memory Address Bus Bit [18:2] – Bit [18:2] of a synchronous
address bus. The memory address is sampled when L_CS# is enabled
and L_ADSC# is asserted.
Local Memory Address Bus Bit [19] or Local Memory Read Chip
Select [3] – Depends on memory configuration, this pin can be used as
the Local Memory Address Bit [19] or as the Local Memory Read Chip
Select [3].
Local Memory Read Chip Select [2:0] – allows up to read one of the 4
banks of memory.
Local Memory Write Chip Select [3:0] – allows up to write one of the 4
banks of memory.
Local Memory Byte Write Enable [3:0] – use to write individual bytes.
Local Memory Controller Address Status – to load a new address.
Local Memory Clock – a synchronous clock to memory devices.
4-Port 10/100M Ethernet Access Controller
Page: 8
D A T A
S H E E T
Rev. 4.0 –December, 1997
EA-224