AN4467 datasheet(8/33 Pages) STMICROELECTRONICS

8 / 33 page

Power supplies

AN4467

8/33

DocID026156 Rev 2

1.1.1

Independent A/D converter supply and reference voltage

To improve conversion accuracy, the ADC and the DAC have an independent power supply

that can be filtered separately, and shielded from noise on the PCB.

•

The ADC voltage supply input is available on a separate VDDA pin

•

An isolated supply ground connection is provided on the VSSA pin

VDDA and VREF+ require a stable voltage. The consumption on VDDA can reach several mA

(see IDD(ADCx), IDD(DAC), IDD(COMPx), and IDDA in the product datasheets for further

information).

When available (depending on the package), VREF- must be tied to VSSA. VSSA and VREF-

must be tied to VSS directly, without any filtering device, this avoids some ESD issues.

On some packages with the pin VREF+ to ensure a better accuracy on low-voltage inputs

and outputs, the user can connect to VREF+ a separate external reference voltage which is

lower than VDD. VREF+ is the highest voltage, represented by the full scale value, for an

analog input (ADC) or output (DAC) signal.

On packages without such a dedicated pin, VREF+ is internally connected to the ADC

voltage supply (VDDA).

AN4467 Datasheet(PDF) 8 Page - STMicroelectronics