Hello,

I would like to ask about AD779x conversion time.

What is effect to conversion time variation? If internal clock variation on AD779x product to product, do you have any information about internal clock variation product to product?

For example, AD779x as single conversion mode, 16.6Hz update rate, 1/4 clock ratio.

At this case, we can estimate AD conversion time as 482ms (1/16.6x2x4). But in fact it takes 492ms on target board (over 10ms than estimation).

Thank you for your help in advance.

Best regards,

Sofy

Hi Sofy,

The internal clock has a 3% tolerance. This includes the variation with temperature and from part to part. The clock frequency determines the conversion time. The values listed in the datasheet are for a 64 kHz clock. If the clock frequency changes by 3%, then the conversion time will also change by 3%. You expect a conversion time of 482 ms and the time that you are measuring is 10 ms longer. So, the difference is (492/482)*100 = 102%. The conversion time is 2% longer so the clock on the part is 64 kHz - 2%.

Regards,

Johnny