Cellular Phone Application

Most mobile appliances allow consumers to switch from built-in speaker and microphone to an external source.  In the case of a cellular phone this will be the earpiece and clip-on microphone for hands-free operation.

Previously relays were used.  However, this took up valuable space, was costly and unreliable for the lifetime of the product.  Today's switching is done using integrated circuits like the PA3535 Dual SPDT (Single Pole Double Throw) Analog switch.