How do I calculate the tolerance on the Vtt supply for DDR3? - How do I calculate the tolerance on the Vtt supply for DDR3? Description When calculating the tolerance for DDR3 Vtt supplies using SSTL15, it is with respect to VCCIO. But you should also take the VCCIO tolerance into the calculation. Vtt(min) = VCCIO(min) * 0.49 Vtt(min) = 1.425V * 0.49 Vtt(min) = 0.70V Vtt(typ) = VCCIO(typ) * 0.5 Vtt(typ) = 1.5V * 0.5 Vtt(typ) = 0.75V Vtt(max) = VCCIO(max) * 0.51 Vtt(max) = 1.575V * 0.51 Vtt(max) = 0.80V The actual tolerance across min and max conditions is /-50mV. This same analysis can be performed for all SSTL and HSTL I/O standards. Custom Fields values: ['novalue'] Troubleshooting novalue False ['novalue'] ['novalue'] novalue novalue ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']