PMIC & audio processor support next-generation hearing aid designs
Next-generation hearing aids, ON Semi comments, will interact wirelessly with their users’ smartphones (control will be a via an app on the phone); and are moving in the direction of using rechargeable batteries rather than the typical zinc-air cells. Supporting these trends, HPM10 is a Power Management Integrated Circuit (PMIC); and Ezairo 7150 SL is a wireless-enabled audio processor.
Ezairo 7150 SL uses ON Semi’s own digital signal processing (DSP) technology and brings wireless connectivity to hearing aids and cochlear implants. It comes as a hybrid module designed to form the core of a complete hearing aid, ands centred on the Ezairo 7100 open-programmable 24 bit mixed-signal DSP platform. The System in Package (SiP) solution provides wireless multi-protocol operation and is optimised for 2.4 GHz band applications, including Bluetooth Low-Energy (BLE). Ezairo 7150 SL integrates EA2M, a low power 2 Mb serial CMOS EEPROM used for storing hearing aid firmware and important parameters. The chip works with microphones specific to the hearing-aid function; ON notes that the noise floor of the microphone channel used in (for example) smartphones is too high.
A complete reference design of a behind-the-ear (BTE) hearing aid includes software, hardware, and firmware which enable advanced wireless features. The control over BLE (CoBLE) function allows hearing aid users to control an array of parameters from their smartphone. The user can adjust the hearing aid’s volume, make program changes, check the battery status, and receive phone alerts (such as incoming calls or text messages). It also features a ‘Find Me’ function to help users quickly locate a misplaced hearing aid. The stereo audio streaming proprietary protocol enables music to be streamed from any external audio source (smartphones, tablet computers, televisions, etc.) through a remote dongle. The connectivity range can reach up to 10m in good surrounding conditions.
The HPM10 is a Power Management IC (PMIC) enables use of rechargeable batteries in hearing aids and hearing implant devices. The PMIC generates the voltage needed by the hearing aid and it also manages the charging algorithms such that the battery autonomy and the number of charging cycles are optimised. The rechargeable chemistries supported include silver−zinc (AgZn), and lithium−ion (Li−ion). HPM10 also detects zinc−air (Zn−Air) and nickel metal hydride (Ni-Mh) batteries but doesn’t charge them. The regulator of the PMIC uses both switching and linear techniques to derive the power rail for the audio processor, depending on the chemistry of the battery and the differential between battery voltage and regulated line. A charger communication interface (CCIF) can pass data to the hearing aid charger during the charging process. Battery parameters such as voltage levels, current levels, temperature and different forms of battery failures can also be communicated. Different charging parameters, representative of battery size and type, can be stored in the HPM10’s on-chip one-time programmable (OTP) memory.
“Our new solutions are set to have real impact on hearing aid design and the end-user experience. Ezairo 7150 SL allows much improved user control over their device directly from any BLE-enabled smartphone. It also allows users to listen to audio from any source, like televisions or HiFi audio systems,” states Michel De Mey, senior director at ON Semiconductor. “By enabling rechargeable technology in hearing aids, HPM10 helps answer the need of our customers and the market to provide rechargeable hearing aids, which is another great step towards increased user friendliness.”
ON Semiconductor; www.onsemi.com
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