The CGS410 is a programmable clock generator which produces a variable frequency clock output for use in graphics disk drives and clock synchronizing applications The CGS410 produces output clocks in CMOS and differential formats The user is able to program the differential output levels to best suit the levels of the interfacing device A common configuration allows PCLK to emulate positive ECL logic levels eliminating the need for TTL to ECL translation The CGS410 is referenced off the XTLIN input which can be configured for either external crystal or external oscillator support All internal frequency generation is referenced from the XTLIN input The CGS410 can also be driven by EXTCLK as desired EXTCLK may serve as the source from a fixed clock (for passthru mode) or as an external VCO input