Hi
In the ADC10D1000 datasheet (page 19) the Vcmo Lim tolerances are stated as 1.15V and 1.35V, Vcmo nominal 1.25V. Temperature coefficient of 38ppm/C is also given
Why are the Lim tolerances so big (1.15V to 1.35V) when Vcmo "is generated as a buffered verison of the internal bandgap reference" (page 53) ?
Does Vcmo actually reflect the bandgap reference voltage or is Vcmo adjusted during calibration or otherwise?
Thanks
Johan
Hi Johan,
The VCMO output is affected by process, voltage, temperature (PVT) variations. The temperature coefficient is 38ppm which is relatively small compared to the limits so the main contributors come from process (part to part variation) and voltage (supply variation).
VCMO is not adjusted during calibration or trimmed during testing. Additionally, VCMO is based on the internal bandgap voltage, but is also dependent on some other circuitry, so its value may be slightly different than VBG. As such, VCMO and VBG are listed as separate line items in the datasheet.
Regards,
Luke LaPointe
High Speed Data Converters
