PFS122 datasheet(60/93 Pages) PADAUK

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PFS122

8bit MTP MCU with 12-bit R-Type ADC

Page 60 of 93

PDK-DS-PFS122-EN_V000-May 28, 2020

Data$0

ADCRL;

Data

Data >> 4;

The ADC can be disabled by using the following method:

ADCC

Disable;

ADCC

5.13.5 How to calculate ADC input voltage VIN

For PFS122, only VDD but not 1.2V bandgap voltage can be selected as the VREF of the ADC. When VDD

is not regulated, users have to use the reading of 1.2V bandgap voltage to deduce the input voltage (VIN)

by the ratio of the readings. The principle is as below:

VBG / VDD = NBG / 4096

....(1)

VIN / VDD = NIN / 4096

....(2)

Where VIN is the analog input voltage

VBG is the 1.2V bandgap voltage

NIN is the corresponding ADC reading of VIN

NBG is the corresponding ADC reading of VBG

VDD is the VDD at the measuring instant

4096 is the full swing reading when VIN=VDD (12bit: 2

12 = 4096)

(2)/(1) we get

VIN/VBG = NIN/NBG

And so

VIN = NIN / NBG *VBG

It means users can firstly get the readings for VIN and VBG respectively in a very short period that VDD

remains unchanged. And then use multiplication and division program module or use look-up table

method to finally get the VIN voltage.

If necessary, please contact FAE for demo code reference.

PFS122 Arkusz danych(PDF) 60 Page - PADAUK Technology.