原理上讲，VREFSD跟内部的那个1.2v的vrefint没有任何关系。
VREFSD是sigmaDelta ADC的参考电压，而Vrefint就是片内自带的
一个比较稳定的电压信号源。
不过，Vrefint可以作为VREFSD，即SD-ADC的参考电压。
手册里有清晰描述：
VREFSD+, VREFSD- = 1.1 to 3.6 V
VREFSD+ and VREFSD- correspond to the reference voltage for SDADCx converters.
They define the input conversion range for all SDADCx converters.
If SDADCx is configured in external reference voltage mode, the external voltage
reference source must be connected to these pins.
If the external reference voltage is not enabled, then the selected SDADC internal
reference voltage source (VREFINT, SDADC_VDD) is present on VREFSD+.
A 10 nF+1 μF capacitor must be placed between VREFSD+ and VREFSD- for
decoupling purposes.
VREFSD+ must be lower than SDADC power supply:
VREFSD+ < min(VDDSD12, VDDSD3).
VREFSD- must be connected to ground.
原理上讲，VREFSD跟内部的那个1.2v的vrefint没有任何关系。
VREFSD是sigmaDelta ADC的参考电压，而Vrefint就是片内自带的
一个比较稳定的电压信号源。
不过，Vrefint可以作为VREFSD，即SD-ADC的参考电压。
手册里有清晰描述：
VREFSD+, VREFSD- = 1.1 to 3.6 V
VREFSD+ and VREFSD- correspond to the reference voltage for SDADCx converters.
They define the input conversion range for all SDADCx converters.
If SDADCx is configured in external reference voltage mode, the external voltage
reference source must be connected to these pins.
If the external reference voltage is not enabled, then the selected SDADC internal
reference voltage source (VREFINT, SDADC_VDD) is present on VREFSD+.
A 10 nF+1 μF capacitor must be placed between VREFSD+ and VREFSD- for
decoupling purposes.
VREFSD+ must be lower than SDADC power supply:
VREFSD+ < min(VDDSD12, VDDSD3).
VREFSD- must be connected to ground.
举报
