AN1753/0405

1/15

Rev. 1.0

AN1830

APPLICATION NOTE

ACHIEVING HIGH ACCURACY AND 13-BIT RESOLUTION

WITH ST7LITE2 ADC

1 INTRODUCTION

The purpose of this application note is to show users of the ST7LITE2 ADC how to achieve 13-

bit resolution with the internal amplifier. It also explains the software methodology, which can

be applied to find and cancel the amplifier offset error. A reference application is shown with

implementation of hardware and software filtering techniques (using an averaging algorithm)

to minimize the ADC error.

Please note the data provided with this application note is for reference only, measured in a

lab under typical conditions (unless specified otherwise) and not tested in production.

2 ST7LITE2 ADC OVERVIEW

The ST7LITE2 features a 10-bit successive approximation converter with internal sample and

hold circuitry. The ADC is connected to 7 multiplexed analog input channels which allow 7 pins

on Port B to be used as input for the ADC. The ADC can be turned ON/OFF using the ADON

bit, which can help to reduce consumption when not in use.

In addition to this it also provides an internal amplifier which can be used for small signal am-

plification.

2.1 ADC FUNCTIONALITY

The ADC can be connected to any of the analog channels by using the CH[2:0] bits in the AD-

CCSR Register. This analog input is connected to internal sample and hold circuitry. The

output of which is then converted into a 10-bit digital result via successive approximation (refer

to Figure 1). The result of the conversion is stored in a 10-bit Data Register (ADCDRH + AD-

CDRL).

1