com90c66 Standard Microsystems Corp., com90c66 Datasheet - Page 45

• Manufacturer Part Number: com90c66
• Description: Arcnet Controller/transceiver With At Interface And On-chip Ram Corporation
• Manufacturer: Standard Microsystems Corp.

OSCILLATOR
The COM90C66 incorporates on-board circuitry
which, in conjunction with an external parallel
resonant crystal, forms an oscillator.
oscillator frequency may vary from 8 MHz to 20
MHz to allow for a variable data rate from 1.0
Mbps to 2.5 Mbps.
FIGURE 13 - DIPULSE GENERATION AND RECEIVE WAVEFORM FOR DATA OF 1-1-0
20MHZ
CLOCK
(FOR
REF. ONLY)
nPULSE1
nPULSE2
DIPULSE
RXIN
100ns
200ns
100ns
400ns
1
The
45
The COM90C66 crystal oscillator has been
designed to work with a parallel resonant
crystal. Only two capacitors are needed (one
from each leg of crystal to ground). The values
of the capacitors are two times the lead
capacitance of the crystal.
contains an internal 1 M
crystal must have an accuracy of 0.020% or
better.
1
resistor. The external
The COM90C66
0