The risk of designing OFF DATA SHEET

Ten years ago I was working for a Brazilian company that develops vehicle tracking devices. That company used to have a design house in Beijing, China and their hardware engineer/designer came from Motorola company. He was an award-winning designer at Motorola and had huge knowledge about electronics.

He developed a nice kind of industrial tablet using a Freescale (now NXP) microprocessor. And this tablet was using the Freescale audio codec SGTL5000, but he decided to create his own analog circuit for the audio codec, instead following the examples from the datasheet (there are about 3 or 4 reference circuits in the datasheet).

The audio quality from that tablet was good, but after some months when to product was already in production we received a lot of SGTL5000 that didn’t work well in the tablet. It was generating too much noise.

After some debugging we discovered that soldering this new audio codec chip in the development board the audio quality still good. Then for some reason the circuit designed by our hardware engineer didn’t work when some factory parameter has changed.

This same thing could happen to any other hardware component, always follow the datasheet. This Maxim AppNote/Tutorial is really good to explain this issue:

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