Wireless Systems Design

EMI+ESD Device Benefits Liquid-Crystal Displays

Compared to their predecessors, modern color displays have high data rates. As a result, it is essential to significantly reduce the display interface's capacitance. This approach will ensure the integrity of the display data as it passes through the interface. To help engineers achieve this goal, the CSPEMI608 low-capacitance EMI filter array has come to market. This highly integrated solution promises to simplify layout while providing up to an 89% board-space savings when compared to discrete solutions.

The filter array is offered in an eight-channel configuration. The CSPEMI608 provides an ideal solution for high-speed LCD data lines, which bridge the two folding sections of "clamshell"-type wireless handsets. In addition to EMI filtering, the solution enables ESD protection on each channel.

The filter array was designed using California Micro Devices' proprietary, low-capacitance, Centurion advanced zener process technology. It features an output capacitance of 15 pF (typical) per channel. That's roughly 50% lower than competing solutions. Every channel's ESD protection diodes are designed and characterized to safely dissipate ESD strikes of ±15-kV contact discharge. This value is well beyond the maximum requirement outlined in the IEC61000-4-2 Level 4 standard.

As an EMI filtering solution, the CSPEMI608 is highly effective in suppressing and attenuating the unwanted frequencies created by the "antenna effect." This effect occurs when high-speed data is passed across the display interface. The filter array features eight integrated pi filters, which enable greater than 30-dB and 40-dB attenuation at 1 GHz and 3 GHz, respectively. With such a high level of attenuation, the CSPEMI608's filters remove high-frequency noise while providing immunity from ESD strikes. Those strikes occur when the handset is flipped open and subjected to constant handling.

The CSPEMI608 EMI filter array is now available. It comes in a 20-bump, chip-scale package (CSP) with a tiny 4.000-×-1.458-mm form factor. In unit quantities of 1000, it is priced at $0.66 each.

California Micro Devices
430 N. McCarthy Blvd. #100, Milpitas, CA 95035-5112; (408) 263-3214, FAX: (408) 263-7846, www.calmicro.com.

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