STM32中VDDA為什么也要接電源才能燒錄程序？

VDDA為所有的模擬電路部分供電，包括：
ADC模塊，復(fù)位電路，PVD（可編程電壓監(jiān)測器），PLL，上電復(fù)位（POR）和掉電復(fù)位（PDR）模塊，控制VBAT切換的開關(guān)等。即使不 使用ADC功能，也需要連接VDDA，強(qiáng)烈建議VDD和VDDA使用同一個(gè)電源供電。VDD與VDDA之間的電壓差不能超過300mV，VDD與VDDA 應(yīng)該同時(shí)上電或調(diào)電。

VDDA,VSSA是模擬部分的電源，因?yàn)樗B接著復(fù)位電路，所以這個(gè)必須接，否則無法下載代碼。

Power supply schemes（供電方案）

?VDD = 2.0 to 3.6 V:external power supply for I/Os and the internal regulator. Provided externally through VDD pins.

? VSSA, VDDA = 2.0 to 3.6 V:external analog power supplies for ADC, reset blocks, RCs and PLL (minimum voltage to be applied to VDDA is 2.4 V when the ADC is used). VDDA and VSSA must be connected to VDD and VSS, respectively.

? VBAT = 1.8 to 3.6 V:power supply for RTC, external clock 32 kHz oscillator and backup registers (through power switch) when VDD is not present.