STMicroelectronics has introduced a IC that delivers superior sound quality from portable music players and feature-phones by excluding high-frequency interference from cellphones. The EMIF04-EAR02M8, measuring 1.5 x 1.7mm, can replace a network of discrete components or two separate ICs, normally designed into the music player's headset-connection circuitry, saving as much as 72 percent of pc-board space. This gives product developers extra freedom to implement new features. High attenuation of signals at frequencies from 900MHz to 1900MHz allows use in handsets for all cellular standards, as well as multi-band products, without lengthy fine-tuning of each design.

Although a small number of single-chip alternatives are available, only ST's filtering and protection IC provides circuits that are individually optimized for the earphone and microphone connections, which require different filter characteristics. ST has achieved this by combining its existing EMIF02-MIC03M6 and EMIF02-SPK02F2 for microphone and speaker interfaces into a single integrated device. Features to help maximize handset battery life include low-resistance earphone circuitry (0.3 Ohms), resulting in efficient driving of the speakers. In addition to its integrated and optimized filtering, the IC also provides required protection against electrostatic discharge (ESD) capable of damaging the handset's internal components. By protecting against ESD spikes up to 30kV in direct contact with the signal connections, this new device is more effective than passive ESD-protection components. The EMIF04-EAR02M8 is available in a micro-QFN 8-lead package, priced at $0.24 for orders over 10,000 units.