COM20022I-HT Standard Microsystems (SMSC), COM20022I-HT Datasheet - Page 27

• Manufacturer Part Number: COM20022I-HT
• Manufacturer: Standard Microsystems (SMSC)

Specifications of COM20022I-HT

• Operating Supply Voltage (typ): 5V
• Operating Supply Voltage (min): 4.5V
• Operating Supply Voltage (max): 5.5V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 48
• Lead Free Status / Rohs Status: Compliant

10 Mbps ARCNET (ANSI 878.1) Controller with 2Kx8 On-Chip RAM
Datasheet
SMSC COM20022I
75176B or
Equiv.
RT
20MHZ
CLOCK
(FOR REF.
ONLY)
nPULSE1
nPULSE2
DIPULSE
RXIN
In typical applications, the serial backplane is terminated at both ends and a bias is provided by the
external pull-up resistor.
The RXIN signal is directly connected to the cable via an internal Schmitt trigger. A negative pulse on this
input indicates a logic "1". Lack of pulse indicates a logic "0". For typical single-ended backplane
applications, RXIN is connected to nPULSE1 to make the serial backplane data line. A ground line (from
the coax or twisted pair) should run in parallel with the signal. For applications requiring different treatment
of the receive signal (like filtering or squelching), nPULSE1 and RXIN remain as independent pins.
External differential drivers/receivers for increased range and common mode noise rejection, for example,
would require the signals to be independent of one another. When the device is in Backplane Mode, the
clock provided by the nPULSE2 signal may be used for encoding the data into a different encoding
scheme or other synchronous operations needed on the serial data stream.
Figure 5.8
COM20022I
100ns
- COM20022I Network Using RS-485 Differential Transceivers
200ns
Figure 5.9
100ns
400ns
1
- Dipulse Waveform for Data of 1-1-0
RBIAS
+VCC
DATASHEET
COM20022I
Page 27
+VCC
1
RBIAS
COM20022I
+VCC
0
RBIAS
Revision 09-27-07
RT