Intermediate
30 min

Create a reliable and innovative current limiting solution with MAX890L and STM32L496AG

Redefining safety and efficiency: The future of current limiting

Current Limit Click with Discovery kit with STM32L496AG MCU

Published Jul 22, 2025

Click board™

Current Limit Click

Dev. board

Discovery kit with STM32L496AG MCU

Compiler

NECTO Studio

MCU

STM32L496AG

Our current limiting solution is engineered to transform control mechanisms, ensuring that current is managed effectively to optimize performance, protect equipment, and enhance safety

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Hardware Overview

How does it work?

Current Limit Click is based on the MAX890L, a high-side low-resistance P-channel switch with an adjustable, accurate, current limit system and thermal shutdown from Analog Devices. The MAX890L limits the output current to a programmed level. When the output current is increased beyond the programmed current limit (1.2A), the current increases through the internal replica amplifier and the resistance applied to the SET pin. The current-limit error amplifier compares the voltage across the SET pin resistance to the internal +1.24V reference and regulates the current back to the lesser of the programmed limit (1.2A). This switch is not bidirectional, which means the input voltage must be higher than the output voltage. The current-limit switch is virtually

ubiquitous in system control and provides a safe means for regulating the current delivered to a load circuit. It increases the load current to a programmed limit but no higher. Typically, the current limit is a function of the voltage across an external resistor, and this voltage serves as the reference for an internal current-limiting amplifier. Replacing the resistor with a digital potentiometer allows you to program the current limit as performed on this Click board™. For this purpose, the digital potentiometer MAX5401 from Analog Devices that communicates with the MCU via a 3-wire SPI serial interface is used to set the resistance on the SET pin of the MAX890L and thus adjust the current limit for the switch. The MAX890L provides an open-drain fault output

with a red LED, labeled FAULT, to indicate when the current reaches its limit or when the temperature exceeds +135°C. Besides the fault-indicator pin, the MAX890L also has an active-low Switch-On pin labeled ON pin of the mikroBUS™ socket used to enable and turn the switch on. This Click board™ is designed to operate with 3.3V and 5V logic voltage levels that can be selected via the VCC SEL jumper. Additionally, there is a possibility in this selection that as a source of logical voltage level, a voltage from an external input terminal in the range from 2.7 to 5.5V can be used. In this way, using a logic voltage level from mikroBUS™ or an external voltage supply allows both 3.3V and 5V capable MCUs to use the SPI communication lines properly.

Current Limit Click hardware overview image

Features overview

Development board

The 32L496GDISCOVERY Discovery kit serves as a comprehensive demonstration and development platform for the STM32L496AG microcontroller, featuring an Arm® Cortex®-M4 core. Designed for applications that demand a balance of high performance, advanced graphics, and ultra-low power consumption, this kit enables seamless prototyping for a wide range of embedded solutions. With its innovative energy-efficient

architecture, the STM32L496AG integrates extended RAM and the Chrom-ART Accelerator, enhancing graphics performance while maintaining low power consumption. This makes the kit particularly well-suited for applications involving audio processing, graphical user interfaces, and real-time data acquisition, where energy efficiency is a key requirement. For ease of development, the board includes an onboard ST-LINK/V2-1

debugger/programmer, providing a seamless out-of-the-box experience for loading, debugging, and testing applications without requiring additional hardware. The combination of low power features, enhanced memory capabilities, and built-in debugging tools makes the 32L496GDISCOVERY kit an ideal choice for prototyping advanced embedded systems with state-of-the-art energy efficiency.

Discovery kit with STM32L496AG MCU double side image

Microcontroller Overview

MCU Card / MCU

STM32L496AG Image

Architecture

ARM Cortex-M4

MCU Memory (KB)

1024

Silicon Vendor

STMicroelectronics

Pin count

169

RAM (Bytes)

327680

Used MCU Pins

mikroBUS™ mapper

Switch Enable
PA4
AN
NC
NC
RST
SPI Chip Select
PG11
CS
SPI Clock
PI1
SCK
NC
NC
MISO
SPI Data IN
PI3
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

Current Limit Click Schematic schematic

Step by step

Project assembly

Discovery kit with STM32H750XB MCU front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Discovery kit with STM32L496AG MCU as your development board.

Discovery kit with STM32H750XB MCU front image hardware assembly
Thermo 21 Click front image hardware assembly
Prog-cut hardware assembly
Thermo 21 Click complete accessories setup image hardware assembly
Board mapper by product7 hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
Discovery kit with STM32H750XB MCU NECTO MCU Selection Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto image step 11 hardware assembly

Track your results in real time

Application Output

1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.

2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.

3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.

Software Support

Library Description

This library contains API for Current Limit Click driver.

Key functions:

  • currentlimit_dev_enable - Device enable function

  • currentlimit_set_limit - Set Current With Predefined Values Limit function

  • currentlimit_set_limit_calc - Set Calculated Current Limit function

Open Source

Code example

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.

/*!
 * @file main.c
 * @brief CurrentLimit Click example
 *
 * # Description
 * This example shows capabilities of Current Limit Click board.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initalizes SPI driver and enables the device.
 *
 * ## Application Task
 * Reading users input from USART terminal and using it as an index for
 * an array of pre-calculated values that define current limit level.
 *
 *
 * @author Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "currentlimit.h"

static currentlimit_t currentlimit;
static log_t logger;

const uint8_t lim_val[ 8 ] = { 223, 241, 247, 250, 252, 253, 254, 255 };
uint16_t lim_data[8] = { 100, 200, 300, 400, 500, 600, 700, 867 };

void display_settings ( void ) {
    log_printf( &logger, "- - - - - - - - - - - - - - - \r\n" );
    log_printf( &logger, " To select current limit \r\n" );
    log_printf( &logger, " Send one of the numbers \r\n" );
    log_printf( &logger, "- - - - - - - - - - - - - - - \r\n" );
    log_printf( &logger, " 1 - Limited to 100 mA \r\n" );
    log_printf( &logger, " 2 - Limited to 200 mA \r\n" );
    log_printf( &logger, " 3 - Limited to 300 mA \r\n" );
    log_printf( &logger, " 4 - Limited to 400 mA \r\n" );
    log_printf( &logger, " 5 - Limited to 500 mA \r\n" );
    log_printf( &logger, " 6 - Limited to 600 mA \r\n" );
    log_printf( &logger, " 7 - Limited to 700 mA \r\n" );
    log_printf( &logger, " 8 - Limited to 867 mA \r\n" );
    log_printf( &logger, "- - - - - - - - - - - - - - - \r\n" );
}

void application_init ( void ) {
    log_cfg_t log_cfg;  /**< Logger config object. */
    currentlimit_cfg_t currentlimit_cfg;  /**< Click config object. */

    /** 
     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
     */
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.

    currentlimit_cfg_setup( &currentlimit_cfg );
    CURRENTLIMIT_MAP_MIKROBUS( currentlimit_cfg, MIKROBUS_1 );
    err_t init_flag  = currentlimit_init( &currentlimit, &currentlimit_cfg );
    if ( SPI_MASTER_ERROR == init_flag ) {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }

    currentlimit_dev_enable( &currentlimit, CURRENTLIMIT_ENABLE );
    log_printf( &logger, "    Click  Enabled!    \r\n" );
    log_printf( &logger, "-----------------------\r\n" );
    Delay_ms ( 100 );
    log_info( &logger, " Application Task " );
    display_settings( );
}

void application_task ( void ) {
    char inx;
    if ( log_read( &logger, &inx, 1 ) != CURRENTLIMIT_ERROR ) {
        if ( inx >= '1' && inx <= '8' ) {
            currentlimit_set_limit( &currentlimit, lim_val[ inx - 49 ] );
            log_printf( &logger, " Selected mode %d, \r\n Current limit is %d mA \r\n", ( uint16_t ) inx - 48, lim_data[ inx - 49 ] );
            log_printf( &logger, "- - - - - - - - - - - - - - - \r\n" );
        } else { 
            log_printf( &logger, "- - - - - - - - - - - - - - - \r\n" );
            log_printf( &logger, " Data not in range! \r\n" );
            log_printf( &logger, "- - - - - - - - - - - - - - - \r\n" );
            display_settings( );
        }
    }
}

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

// ------------------------------------------------------------------------ END

Additional Support

Resources

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