ADC 12 Click is a compact add-on board that contains a fully-featured, general-purpose analog-to-digital converter. This board features the ADS7828, a low-power 12-bit data acquisition device that features a serial I2C interface and an 8-channel multiplexer from Texas Instruments. The A/D converter features a sample-and-hold amplifier and an internal, asynchronous clock. The combination of an I2C serial interface, up to eight differential analog inputs, built-in reference with buffered output, and micro-power consumption makes this Click board™ ideal for applications requiring the A/D converter to be close to the input source in remote locations and for applications requiring isolation.
ADC 12 Click is supported by a mikroSDK compliant library, which includes functions that simplify software development.
ADC 12 Click is based on the ADS7828, a low-power 12-bit data acquisition device that features a serial I2C interface and an 8-channel multiplexer from Texas Instruments. The architecture of the ADS7828, which is a classic Successive Approximation Register (SAR) A/D converter, is based on capacitive redistribution that inherently includes a sample-and-hold function. It has an integrated I2C input and output port as well as screw terminal connectors for each analog input channel. It is controlled by an internally generated free-running clock. When the ADS7828 is not performing conversions or being addressed, it keeps the A/D converter core powered off, and the internal clock does not operate.
When the A/D converter enters the Hold mode, the voltage on the selected channel pin of the input terminal is captured on the internal capacitor array. The input current on the analog inputs depends on the conversion rate of the device. During the sample period, the source must charge the internal sampling capacitor. After the capacitor has been fully charged, there is no further input current. The amount of charge transfer from the analog source to the converter is a function of conversion rate.
ADC 12 Click communicates with MCU using the standard I2C 2-Wire interface with a frequency up to 100kHz in the Standard, up to 400kHz in the Fast, and up to 3.4MHz in the High-Speed mode. It also allows the choice of the last two least significant bits (LSB) A0 and A1 by positioning SMD jumpers labeled as ADDR SEL to an appropriate position marked as 0 and 1. This Click board™ also posses a jumper for selecting the reference voltage labeled as VREF SEL. The ADS7828 can operate with an internal 2.5V reference or an external reference (in this case logic voltage level VCC), which can be selected by positioning SMD jumpers to an appropriate position marked as INT and EXT.
This Click board™ is designed to be operated with both 3.3V and 5V logic voltage levels that can be selected via VCC SEL jumper. This allows for both 3.3V and 5V capable MCUs to use the I2C communication lines properly. However, the Click board™ comes equipped with a library that contains easy to use functions and an example code that can be used as a reference for further development.
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