COM20019I_0610 Datasheet, PDF (46/70 Pages) SMSC Corporation – Cost Competitive ARCNET (ANSI 878.1) Controller with 2K x 8 On-Chip RAM

RAM
Cost Competitive ARCNET (ANSI 878.1) Controller with 2K x 8 On-Chip
If an external crystal is used, two capacitors are needed (one from each leg of the crystal to ground). No
external resistor is required, since the COM20019I 3V contains an internal resistor. The crystal must have
an accuracy of 0.020% or better. The oscillation frequency range is from 10 MHz to 20 MHz.
The crystal must have an accuracy of 0.010% or better when the internal clock multiplier is turned on. The
oscillation frequency must be 20MHz when the internal clock multiplier is turned on.
The XTAL2 side of the crystal may be loaded with a single 74HC-type buffer in order to generate a clock
for other devices.
The user may attach an external TTL clock, rather than a crystal, to the XTAL1 signal. In this case, a
390Ω pull-up resistor is required on XTAL1, while XTAL2 should be left unconnected.
Rev. 10-31-06
Page 46
DATASHEET
SMSC COM20019I 3.3V Rev.C