ISO ADC 7 Click

How does it work?

ISO ADC 7 Click is based on the AMC131M03, a three-channel, 24-bit delta-sigma (ΔΣ) ADC with simultaneous sampling capabilities from Texas Instruments, designed for applications requiring precise multi-channel data acquisition, such as electricity meters, battery management systems, EV charging stations, and circuit breakers. The AMC131M03 includes a silicon-dioxide (SiO2)-based capacitive isolation barrier that provides 5000-VRMS isolation (certified by UL1577) for 1 minute, offering excellent immunity to magnetic fields and enhanced safety for use in industrial and high-voltage applications. Additionally, the AMC131M03 meets low EMI standards (CISPR-11 and CISPR-25), ensuring reliable performance in environments with stringent electromagnetic compatibility requirements.

Each of the three channels (AIN0-AIN2) of the AMC131M03 includes a built-in digital decimation filter that demodulates the output of the ΔΣ modulator, enabling data rates up to 64kSPS per channel in high-resolution mode. This filter significantly reduces quantization noise, providing a wide dynamic range. The relative phase of the samples between channels can also be adjusted, compensating for any phase delay in sensor responses.

Additionally, the modulator’s frequency is derived from a user-selectable clock source, which can be configured via the CLK SEL switch, allowing the choice between 4.096 MHz and 8.192 MHz. The main clock is activated using the XEN pin. A programmable clock divider provides flexibility in setting the modulator’s frequency to match specific application needs, further optimizing the device’s performance. Thus, as mentioned, the digital decimation filter enhances the signal-to-noise ratio by filtering out-of-band noise, resulting in improved accuracy and efficiency.

The AMC131M03 also integrates a low-drift internal voltage reference and a high-precision programmable gain amplifier (PGA), offering gains up to 128. Its integrated precharge buffer ensures high input impedance when the PGA gain exceeds 4, enabling accurate measurements of signals with small amplitudes. The ADC also incorporates a negative charge pump, allowing absolute input voltages as low as 1.3V, making it ideal for single-ended power supply systems measuring signals close to ground.

This Click board™ communicates with the host MCU via a standard SPI interface. Additional control pins include the RST pin, which can be used both as a reset and for synchronization across multiple AMC131M03-based devices, and the RDY pin, which serves as a data-ready interrupt signal. These features allow for flexible and synchronized multi-channel data acquisition, ensuring precise timing and data integrity.

A key feature of the AMC131M03 is its integrated temperature sensor, which supports both internal and external temperature measurements. The AIN2 input channel is multiplexed with the temperature sensor, and users can select between internal and external sensing modes through register settings. The AIN2 SEL jumper on the Click board™ allows for selecting the type of external temperature coefficient (TC) element. In the “EXT” position, the jumper enables the use of an external positive (PTC) or negative temperature coefficient (NTC) element, while the “NTC” position activates the onboard NTC sensor for direct temperature measurement.

This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.

Specifications

Pinout diagram

This table shows how the pinout on ISO ADC 7 Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
	NC	1	AN	PWM	16	XEN	Main Clock Enable
Reset / Synchronization / ID SEL	RST	2	RST	INT	15	RDY	Data Ready
SPI Select / ID COMM	CS	3	CS	RX	14	NC
SPI Clock	SCK	4	SCK	TX	13	NC
SPI Data OUT	SDO	5	MISO	SCL	12	NC
SPI Data IN	SDI	6	MOSI	SDA	11	NC
Power Supply	3.3V	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

ISO ADC 7 Click electrical specifications

Software Support

We provide a library for the ISO ADC 7 Click as well as a demo application (example), developed using MIKROE compilers. The demo can run on all the main MIKROE development boards.

Package can be downloaded/installed directly from NECTO Studio Package Manager (recommended), downloaded from our LibStock™ or found on MIKROE github account.

Library Description

This library contains API for ISO ADC 7 Click driver.

Key functions

• isoadc7_read_voltage This function reads the voltage measurements of all three channels.

• isoadc7_read_data This function reads the status register and raw data of all three channels.

• isoadc7_set_gain This function sets the gain level for all channels.

Example Description

This example demonstrates the use of ISO ADC 7 Click by reading and displaying the voltage levels from 3 isolated analog input channels.

void application_task ( void ) 
 { 
     float ch0 = 0; 
     float ch1 = 0; 
     float ch2 = 0; 
     if ( ISOADC7_OK == isoadc7_read_voltage ( &isoadc7, &ch0, &ch1, &ch2 ) ) 
     { 
         log_printf ( &logger, " CH0: %.1f mVrn", ch0 ); 
         log_printf ( &logger, " CH1: %.1f mVrn", ch1 ); 
         log_printf ( &logger, " CH2: %.1f mVrnn", ch2 ); 
         Delay_ms ( 1000 ); 
     } 
 }

The full application code, and ready to use projects can be installed directly from NECTO Studio Package Manager (recommended), downloaded from our LibStock™ or found on MIKROE github account.

Other MIKROE Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.ISOADC7

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 Click or RS232 Click to connect to your PC, for development systems with no UART to USB interface available on the board. UART terminal is available in all MIKROE compilers.

mikroSDK

This Click board™ is supported with mikroSDK – MIKROE Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.

For more information about mikroSDK, visit the official page.