New spread spectrum oscillator offers low-EMI drop-in replacement

Euroquartz offers a new spread spectrum oscillator, providing customers with a drop-in replacement for standard clock oscillators with a reduction in EMI by as much as 12dB.

In electronic systems, a principal cause of EMI is the system clock oscillator and traditional 'patching-up' methods of combatting interference – ferrite beads, ground planes, metal shielding and similar – are often costly and awkward to implement and most frequently applied after a system has failed EMI testing.

The most efficient method to reduce EMI is to suppress it at source, and the company's new EQHM22 does precisely that. Compared with conventional clock oscillators, spread spectrum (dithered) oscillators can decrease EMI by up to 12dB, and the parts are drop-in replacements for standard components, so there is no necessity to redesign existing PCBs.

Providing a choice of modulation rates and spreads, these new devices offer frequencies from 16MHz to 40MHz in a miniature surface mount package measuring 2.5mm x 2mm x 0.9mm. Frequency stability is available as low as ±25ppm in commercial (0C to 70C) and industrial (-40C to +85C) grades with input voltages of 1.8, 2.5 and 3.3VDC available, all ±10%. Output logic is CMOS with a load capability of 15pF.

Additional specifications include current consumption of 4, 5 or 6mA depending on voltage model, rise/fall times from 7ns to 10ns, start-up time of 1ms typical, 5ms maximum, output enable/disable function and duty cycle of 50% ±10%. Ageing is ±5ppm/year maximum at 25C ambient temperature.

The company's new low EMI oscillators are excellent for use in a wide range of applications, including printers and multifunction printers, digital copiers, PDAs, networking LAN/WAN and routers, storage systems such as CD-ROM, DVD and HDD, scanners, modems, projectors, embedded systems, automotive GPS navigation systems, LCD PC monitors and TVs, ADSL, PCMCIA devices and digital cameras.

The low EMI oscillators are provided in EIA 16mm tape and reel packaging for volume production requirements.