For some early samples of Zynq-7020 devices, the on-chip voltage reference for the XADC was not trimmed correctly during the test program.
Only the Z-7020 9921 ESLAB devices (earliest samples) are affected by this errata item
This leads to inaccurate voltage and temperature measurements.
The external voltage references can be used for accurate measurements.
Refer to the XADC Pinout Requirements figure in (UG480), 7 Series FPGAs XADC Dual 12-Bit 1MSPS Analog-to-Digital Converter User Guide.
Refer to (Xilinx Answer 44971) for additional information.
Work-around: Use an external reference for the XADC.
Configurations Affected: Systems that use XADC.
Device Revision(s) Affected: Refer to (Xilinx Answer 47916) - Zynq-7000 Design Advisory Master Answer Record.