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STM delivers handset audio filtering and ESD in flip-chip package

By combining complete EMI filtering and ESD protection for stereo headset output and external and internal microphones in a single package, STMicroelectronics' EMIF06-AUD01F2 saves up to 77% of board space compared to previous discrete solutions.

The flip-chip package measuring 2.42 x 1.92mm provides superior audio performance in feature-rich mobile phones by eliminating audible handset demodulation noise, or 'bumble-bee' noise. The EMIF06-AUD01F2 achieves −25dB attenuation (S21) throughout the stop-band 800-2480MHz using high-density 1.3nF PZT (lead, zirconate titanate) capacitors on the microphone lines.

The device also achieves high ESD protection through the combination of integrated TVS (transient voltage suppressor) diodes, low-inductance packaging, and the Z-R-Z pi-filter topology.

According to STM, the EMIF06-AUD01F2 is the first device to combine filtering and ESD protection for all handset speaker and microphone channels.

It saves more than 50% of board space compared to previous integrated solutions using two ICs with external resistors, and up to 77% compared to alternative discrete solutions.

All necessary biasing circuitry is also integrated, as well as a 10-ohm series resistor in the speaker output, thereby minimizing external components. The low package profile of 0.65mm also helps designers implement high functionality within cutting-edge, ultra-slim handset styles.

The integrated TVS diodes have a 20V peak clamping voltage, enabling the device to meet IEC61000-4-2 level 4 ESD protection at the external pins. Total harmonic distortion (THD) is less than −75dB, while the device achieves high audio-power transfer by delivering 135mA per speaker channel ensuring excellent sound reproduction.

This is achieved thanks to the high thermal efficiency of the wafer-level flip-chip package, which supports 285mW total continuous power dissipation.

The EMIF06-AUD01F2 is already in volume production, and is available at $0.55 for 1000 pieces. A datasheet is available at www.st.com/stonline/products/literature/ds/14447/emif06-aud01f2.pdf .

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