COM20020ILJP3V Standard Microsystems (SMSC), COM20020ILJP3V Datasheet - Page 35

• Manufacturer Part Number: COM20020ILJP3V
• Manufacturer: Standard Microsystems (SMSC)

Specifications of COM20020ILJP3V

• Number Of Transceivers: 1
• Operating Supply Voltage (typ): 3.3V
• Operating Temperature (max): 85C
• Operating Temperature (min): -40C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 28
• Lead Free Status / RoHS Status: Not Compliant

5Mbps ARCNET (ANSI 878.1) Controller with 2K x 8 On-Chip RAM
7.3 Internal Ram
The integration of the 2K x 8 RAM in the COM20020I represents significant real estate savings. The most obvious
benefit is the 48 pin package in which the device is now placed (a direct result of the integration of RAM). In addition,
the PC board is now free of the cumbersome external RAM, external latch, and multiplexed address/data bus and
control functions which were necessary to interface to the RAM. The integration of RAM represents significant cost
savings because it isolates the system designer from the changing costs of external RAM and it minimizes reliability
problems, assembly time and costs, and layout complexity.
SMSC COM20020I 3.3V
BIT
1,0
Reconfiguration
Timer 1, 0
D0-D7
BIT NAME
I/O Address 02H
FIGURE 8 – SEQUENTIAL ACCESS OPERATION
High
RCNTM1,0 These bits are used to program the reconfiguration timer as a
Address Pointer Register
SYMBOL
I/O Address 04H
11-Bit Counter
Data Register
DATASHEET
I/O Address 03H
function of maximum node count. These bits set the time out
period of the reconfiguration timer as shown below. The
time out periods shown are for 5 Mbps.
Note*: The node ID value 255 must exist in the network for
26.25 mS timeout to be valid.
RCNTM1
Low
0
0
1
1
Page 35
Data Bus
Memory
RCNTM0
Address Bus
Memory
8
0
1
0
1
11
DESCRIPTION
420 mS
105 mS
52.5 mS
26.25 mS*
Time Out
Period
INTERNAL
2K x 8
RAM
Up to 255 nodes
Up to 64 nodes
Up to 32 nodes
Up to 16 nodes
Max Node Count
Revision 12-06-06