Wolfson 公司的WM2002是采用Wolfson myZoneTM環境噪音消（ANC）除技術的立體聲耳機驅動器，可采用單端或BTL輸出配置，支持模擬播放或語音輸入，模擬或數字麥克風。WM2002集成了功率管理，包括DC/DC轉換器，電荷泵和LDO穩壓器，采用單節AAA電池供電。環境噪音可降低25dB(典型值),降噪帶寬(40Hz -4kHz) ，BTL驅動的THD+N可達-80dB。主要用在帶ANC的手機，耳機以及藍牙單聲道/立體聲手機。本文介紹了WM2002主要特性，方框圖，典型應用框圖以及推薦外接元件數值和DC1升壓轉換器和電荷泵外接元件數值。
Stereo Headphone Driver with Wolfson myZoneTM Ambient Noise Cancellation
The WM2002 is a low power, high quality stereo headphone driver, delivering Wolfson’s patented myZoneTM ambient noise cancellation in a single-ended or BTL (bridge-tied-load) output configuration. The WM2002 supports analogue playback or voice input, and analogue or digital microphone inputs for noisemonitoring microphones.
Designed for embedded applications or incorporated within a stand-alone headset or headphone, the Wolfson myZone™ ANC noise cancellation engine performs ambient noise cancellation during a voice call or during music playback.
The ambient noise input is supported via single-ended or differential analogue microphone interfaces; digital microphone input is also supported. Up to 10 noise input microphones can be supported at once.
The WM2002 provides integrated power management, comprising a DC-DC converter, Charge Pump and LDO Regulators. Many different power supply configurations are thus supported. The entire device can be powered from a single cell AAA battery, or from 2xAAA cells, or from an external regulated supply.
System clocking is achieved using an on-chip oscillator. An external clock can be connected directly, if available. The WM2002 is configured using programmable settings stored in an integrated non-volatile memory. The configuration stored in the OTP memory is enabled automatically at start-up. If required, the WM2002 can also be configured using register control accessed using a 2-wire serial control interface.
WM2002主要特性：
Wolfson myZone™ Ambient Noise Cancellation (ANC)
- >30dB (peak), 25dB (typical) ambient noise reduction*
- Wide noise cancellation bandwidth (40Hz to 4kHz)*
- * depending on acoustic configuration
- Multiple banks of ANC coefficients can be programmed to support different operating conditions
Audio inputs
- Up to 10 analogue or digital microphones
- Single-ended or differential analogue microphone input
- 2 single-ended or 1 differential line input per channel
Headphone driver (LDO4VOUT = 1.8V)
- 45mW per channel into 16ohm load
- 22mW per channel into 32ohm load
- Single-ended or differential (BTL) drive configuration
- -80dB THD+N for differential (BTL) drive
Integration
- On-chip DC-DC boost converter, charge-pump and LDOs
- Flexible power supply options, including single cell battery (1 x AAA battery) or (2 x AAA/AAAA)
- Internal crystal oscillator
Miscellaneous
- Monitor pin to select mute / talk-through modes
- LED driver
- Tone generator for audible status indication
- Pop and click noise protection circuit
- RFI suppression
- 48-pin QFN package (7 x 7 x 0.75mm, 0.5mm pitch)
WM2002應用：
“Pod-style” stereo ear-buds, headsets, headphones with ANC
“Supra-Aural” stereo headphones with ANC
Mono/Stereo Bluetooth headsets with ANC
圖1 WM2002方框圖
圖2 WM2002典型應用框圖
圖3 WM2002推薦外接元件數值
圖4 WM2002 DC1升壓轉換器和電荷泵外接元件數值
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