On page 207 of stm32 reference manual, it says that VSSA(power supply of ADC, negative) must be tied to VREF-(analog reference, negative). But when I refer to reference design of STM32(Evaluation board).On page 39, it shows a conflic design:
when i choose not to solder R41 and apply a real negative voltage (-3v3) to VREF-, the two pins(VREF- and VSSA) do not connect. So, which one is the right solution?
In addition, VREF+ VREF- VDDA VSSA have relations to accuracy, so I choose to add two magnetic bead:
Is that reasonable?