© 2000 Scenix Semiconductor, Inc. All rights reserved. 131 SX User’s Manual Rev. 3.1 www.scenix.com Chapter 4 Clocking, Power Down, and Reset frequency can vary significantly due to reliance on the small parasitic capacitance associated with the
PCB traces and device package. 4.2.4 External Crystal/Resonator (XT, LP, or HS Mode) Using  an  external  crystal  or  ceramic  resonator  to  generate  the  clock  is  suitable  for  a  system  that requires precise and accurate timing (for example, for a real-time clock). These types of oscillators cost
more than RC oscillators. The SX device can be configured to operate in any one of the following external crystal/resonator
modes. SX18/20/28AC and SX18/20/28AC75: • LP1– low-power crystal (32 KHz) • LP2 – low-power crystal /resonator(32 KHz to 1 MHz) • XT1 – normal crystal/resonator (32 KHz to 10 MHz) • XT2 – normal crystal/resonator (1 MHz to 24 MHz) • HS1 – high-speed crystal/resonator (1 MHZ to 32 MHz) • HS2 – high-speed crystal/resonator (1 MHZ to 50 MHz) • HS3 – high-speed crystal/resonator (1 MHZ to 50 MHz) Figure 4-1 External RC Oscillator Connections V_DD R C Internal
Circuitry OSC2 OSC1 N ~ SX Device