xr82c684 Exar Corporation, xr82c684 Datasheet - Page 56

• Manufacturer Part Number: xr82c684
• Description: Cmos Quad Channel Uart Quart
• Manufacturer: Exar Corporation

Note: The user also has an option to drive the Oscillator Circuit with a TTL input signal, in lieu of using a crystal oscillator.
If this approach is used, the TTL must be driven into the X1/CLK pin, and the X2 pin must be left floating.
Note:
XR82C684
Figure 30. A Recommended Schematic to Drive Multiple QUARTs from the Same Crystal Oscillator
The user is urged not to use the 74LS14 Schmitt Trigger Inverter in lieu of the 74HC14 device. The input of the
74LS14 tends to load down the oscillating signal from the QUART, to the point that the Schmitt Trigger inverter
can no longer change state or respond to the oscillator signal.
Figure 29. Recommended Schematics for the XTAL Oscillator Circuitry
XR82C684
XR82C684
74HC14
Figure 30
XR82C684