We consider the VREF_OUT voltage drift.
In DataSheet Table 36. VREF full-range operating behaviors ,
It is described that VOUT = 1.198 V (max);( Vout Voltage reference output with factory trim at nominal VDDA and temperature= 25 °C ) .
Vtdrift = 15mV ( max ) ;(Vmax -Vmin across the full temperature range)
Vvdrift = 2mV ( max );(Vmax -Vmin across the full voltage range)
Table 38. VREF limited-range operating behaviors ,
It is described that VOUT = 1.225 V (max);temperature= 0 ~ 50 °C
We calculated a max case value for voltage drift.
1.198 + 0.015 + 0.002 = 1.215
Why is the max case value ( we calculated) smaller than Table 38 value ?
1.215 < 1.225