Handy S/PDIF Checker

Audio equipment with digital signal interfaces offer high quality sound but trying to listen to what is happening at the interface is not easy without specialised test equipment. A new S/PDIF decoder chip with built-in D/A converters forms the heart of this simple but useful piece of test kit.The S/PDIF audio digital interface standard has been around for a few years now and is increasingly being adopted by the latest models of CD players, DAT recorders and mini disc systems. Trouble-shooting digital systems invariably calls for the use of expensive test gear to analyse the signals. This circuit idea offers a simple low-cost method of listening-in to the digital interface.This design uses just one 28-pin SMD chip that together with a voltage regulator and a few passive components produces a useful S/PDIF interface tester. The IC in question is the recently introduced IEC-958 Audio DAC type UDA1350ATS or UDA1351TS from Philips.