This document describes the features and characteristics of the ST10F269/ST10F280 chip, including a 10-bit resolution analog-to-digital converter, a 4.85µs conversion time, an on-chip sample and hold circuit, ESD protected analog inputs, and a total unadjusted error of ±2LSB across the whole automotive temperature range.
This document is an application note for the ST10F269 and ST10F280 microcontrollers, which feature a 10-bit Analog-to-Digital Converter (ADC). It identifies the primary sources of ADC error, including analog input signal errors, input overload errors, and reference voltage errors. The text details how factors like source internal resistance, high-frequency noise, and reference voltage stability impact conversion accuracy.
| ADC Resolution | 10-bit |
|---|---|
| Conversion Time | 4.85us |
| Total Unadjusted Error | + 2LSB |
| Input Leakage Current | maximum + 200 nA |
| Pin Capacitance | maximum 10 pF |
| ADC Internal Capacitance | maximum 5 pF |
| Series Input Resistance | maximum 1.5kQ |
| Input Overload Current | up to 10mA |
Analog input signal error can be caused by poor matching of source internal resistance with ADC input parameters, voltage drops due to leakage current, or noise from the analog input signal.
The input analog signal should always be low pass filtered to ensure that high frequencies are rejected during the sampling time.
During overload, internal protection diodes sink current to reduce the voltage, which affects ADC performance and may cause accuracy loss or damage if limits are exceeded.
Error is reduced by careful PCB routing, decoupling, placing the source close to the pin, ensuring low impedance, and matching the reference voltage internal resistance to the conversion time.