![]() ![]() Positive offset error representation Figure 8. Step 2: If MSB = 0, then compare with ¼ VREF Figure 7. ![]() Step 2: If MSB = 1, then compare with ¾ VREF Figure 6. Basic schematic of SAR switched-capacitor ADC (example for 10-bit ADC) Figure 2. Stm32x device protected software#source and parasitic capacitors Temperature-effect compensation /45 DocID15067 Rev 2ģ Contents Minimizing injection current Minimizing I/O pin crosstalk EMI-induced noise reduction PCB layout recommendations Component placement and routing Software methods to improve precision Averaging samples Digital signal filtering FFT for AC measurement ADC calibration Minimizing internal CPU noise High impedance source measurement ADC input stage problem Explanation of the behavior Minimizing added errors Source of described problem - ADC design Conclusion Revision history DocID15067 Rev 2 3/45 3Ĥ List of figures List of figures Figure 1. Stm32x device protected how to#Applicable products Product family Part numbers Microcontrollers STM32F0xx STM32F1xx STM32F2xx STM32F3xx STM32F4xx STM32L1xx September 2013 DocID15067 Rev 2 1/45Ģ Contents Contents 1 ADC internal principle SAR ADC internal structure ADC errors ADC errors related to the ADC itself Offset error Gain error Differential linearity error Integral linearity error Total unadjusted error ADC errors related to its environment Reference voltage noise Reference voltage / power supply regulation External reference voltage parameters Analog input signal noise ADC dynamic range bad match for maximum input signal amplitude Effect of the analog signal source resistance Effect of source capacitance and parasitic capacitance of the PCB Injection current effect Temperature influence I/O pin crosstalk EMI-induced noise How to get the best ADC accuracy Reduce the effects of ADC-related ADC errors Minimize ADC errors related to external environment of ADC Reference voltage / Power supply noise minimization Reference voltage / Power-supply regulation Analog-input signal noise elimination Adding white noise or triangular sweep to improve resolution Matching the ADC dynamic range to the maximum signal amplitude Analog source resistance calculation Source frequency condition vs. It is divided into three main parts: a simplified description of ADC internal structure to aid understanding of ADC operation and related ADC parameters explanations of the different types and sources of ADC errors related to the ADC design and to external ADC parameters such as the external hardware design recommendations on how to minimize these errors, focusing on hardware and software methods This document applies to the products listed in Table 1 which are referred to as STM32x throughout this document. This application note aims to help understanding of ADC errors and how to enhance ADC accuracy. ADC accuracy does not depend on ADC performance and features alone, it depends on the overall application design around the ADC. To improve this accuracy, you need to understand the errors associated with the ADC and the parameters affecting them. ![]() In applications involving analog-to-digital conversion, ADC accuracy has an impact on the overall system quality and efficiency. A self-calibration feature is provided to enhance ADC accuracy versus environmental condition changes. Stm32x device protected series#1 Application note How to get the best ADC accuracy in STM32Fx Series and STM32L1 Series devices Introduction The STM32Fx Series and STM32L1 Series microcontroller families embed up to four advanced 12-bit ADCs (depending on the device). ![]()
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