Vref Virtual ground, in a PDIP8 package Based on this paper: https://www.ti.com/lit/an/sbva002/sbva002.pdf https://l.facebook.com/l.php?u=https%3A%2F%2Fgithub.com%2Fda6353%2FVref%3Ffbclid%3DIwZXh0bgNhZW0CMTEAAR1YYSdaZmJQTInOCMU4OK5hUXoQJnnteBDRCC_r7G96EA1hHZP52402e3k_aem_pgm3NdlbhVuk-1I4EkfesA&h=AT10sP992uQ2v7GivCy05ZsJV2U-RpoUXTEONibHl7-vwVt3iGbaf28fRjfjl0zNPMJ7LhQa40hGEv78saXLO7Caq5pcPyhiaEnxdyNE4-u_cSICnrpTv1C4xrrQHkVa8MkdlvljCcTv&s=1