AS3502 EB

AS3500 AS3501 AS3502 D a ta S h e e t L o w P o w e r A m b i e n t N o i s e - C a n c e l l i n g Spe a k e r D r i v e r 1 General Description Line Input volume control via serial interface or volume pin The AS3500/01/02 are speaker driver with Ambient Noise Cancelling function for handsets, headphones or ear pieces. It is intended to improve quality of e.g. music listening, a phone conversation etc. by reducing background ambient noise. 64 steps @ 0.75dB and MUTE, pop-free gain setting single ended stereo or mono differential mode ANC processing The fully analog implementation allows the lowest power consumption, lowest system BOM cost and most natural received voice enhancement otherwise difficult to achieve with DSP implementations. The device is designed to be easily applied to existing architectures. feed-forward cancellation An internal OTP-ROM can be optionally used to store the microphones gain calibration settings. 12-30dB noise reduction (headset dependent) The AS3500/01/02 can be used in different configurations for best trade-off of noise cancellation, required filtering functions and mechanical designs. The simpler feed-forward topology is used to effectively reduce low frequency background noise. The feed-back topology with either 1 or 2 filtering stages can be used to reduce noise for a larger frequency range, and to even implement transfer functions like speaker equalization, Baxandall equalization, high/low shelving filter and to set a predefined loop bandwidth. The filter loop is optimized by the user for specific handset electrical and mechanical designs by dimensioning simple R, C components. Most handset implementations will make use of a single noise detecting microphone. Two microphones could be used to allow for increased flexibility of their location in the handset mechanical design. Using the bridged mode allows to even drive high impedance headsets. feed-back cancellation with filter loop transfer function definable via simple RC components simple in production SW calibration 10-2000Hz wide frequency active noise attenuation (headset dependent) Monitor Function for assisted hearing, i.e. to monitor announcements fixed (OTP prog.) ambient sound amplification to compensate headphone passive attenuation volume controlled ambient sound amplification mixed with fixed (OTP prog.) attenuation of LineIn Incremental Functions ANC with or without music on the receiving path improved dynamic range playback simple and low cost single noise detection microphone implementation OTP ROM for automatic trimming during production Performance Parameter 5/3.8mA @ 1.5V stereo/mono ANC;