The low-cost oscillators offer the significant advantage of reducing EMI at source, i.e. the system clock oscillator, so that there is no need to employ costly shielded backplanes, ferrite cores and similar techniques to reduce EMI.
series low-EMI oscillators are available with a choice of modulation rates and spread type. A Spread Spectrum oscillator disperses the mode energy over a wide bandwidth. This is achieved by the frequency modulation technique which may be applied to the down side of the nominal frequency (known as down spread) or spread equally either side of nominal (called centre spread). The majority of applications use Centre Spread although Down Spread is the preferred technique if overclocking would cause system problems.
Common specifications for the new HM18 oscillators are frequency range from 12.5 to 42.0MHz, CMOS output logic, DC input voltage of 1.8V ±0.15V, frequency stability options of ±25ppm, ±50ppm and ±100ppm for commercial (0 to +70°C) and industrial (-40 to +85°C) devices, rise/fall times of 2.5ns maximum, 15pF load and start-up time 2ms typical. Duty cycle is 50% ±10%, standard, cycle to cycle jitter is ±100ps maximum and ageing is ±5ppm/year maximum at 25°C.
Supplied on EIA 16mm tape and reel in quantities of 1000, the new 18HM series low EMI, low voltage oscillators are RoHS compliant and lead-free. The devices are reflow solder compatible and can withstand two processes at 260°C for 10 seconds maximum.