External input for car-audio system

Device purpose:

This device provides the external audio input for car-audio system. So customer can listen not only car-audio, but any external audio signal source. Such as tablet PC, smart phone and so on. The main benefit of this design is the usage of differential stereo inputs what is solving the electric-noise problem in car-audio systems. User can switch the desired audio source (main car-audio or external source) by pushing only one tact switch. Small form factor provides ability of embedding into ordinary car-audio.

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Parameters:
- differential stereo input
- frequency range - 10 - 20 000 Hz (1 db range)
- distortion rate - 0.002% (1 kHz)
- input impedance - 100 kOhm
- dimensions - 25*35 mm
- absence of switching noise
- own noise - 3 uV for chanel
- electric noise suppression rate - 57 dB per chanel
- temprature range -  -30 - +85 C
PCB: