Step down the input voltage with MP9943A and STM32F302VC to achieve the desired output level
Power down, boost efficiency
Published Jul 22, 2025
Click board™
Buck 9 Click
Dev. board
CLICKER 4 for STM32F302VCT6
Compiler
NECTO Studio
MCU
STM32F302VC
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Hardware Overview
How does it work?
Buck 9 Click is based on the MP9943, a high-efficiency 3A peak, 36V, synchronous step-down converter with Power Good from Monolithic Power Systems (MPS). The MP9943 utilizes a peak-current-mode control architecture, ensuring an exceptional transient response and stabilization of the feedback loop. Besides its protection features, MP9943 is also equipped with a soft-start function and a sync option, making this Click board™ a handy solution for developing applications that require a regulated power supply. The feedback voltage on the FB pin of the converter determines the output voltage, and thanks to a voltage divider and an SMD jumper labeled VOUT SEL, which can connect one of two available voltage divider resistors, it allows the output to be set to either 3.3V or 5V. The MP9943 has other advanced features, including synchronization with the external clock from 200kHz to 2.2MHz over the EN/SYNC pin routed to the mikroBUS™ ESY (default PWM) pin. The same pin is also used
as a Chip Enable for the device. The MP9943 operates at a high (fixed) switching frequency of 410kHz, allowing a good compromise between the efficiency and the size of the external components. Thanks to its ability to work with the high-duty cycle of the internal switching PWM signal, the MP9943 requires the input voltage to be only about 0.7V above the output voltage to maintain the regulation. However, the device cannot operate properly if the input voltage drops under 3.3V. Therefore, the under-voltage protection shuts down the device as a protection measure. The under-voltage protection is disabled once the input voltage exceeds 3.5V. This small hysteresis of 0.2V prevents erratic behavior in border cases. Therefore, the supply at the input terminal should stay between 4V and 36V. However, if the output voltage is set to 5V, the voltage at the input should be approximately 5.8V to 6V at least to provide good regulation at the output. The over-current protection is based on cycle-by-cycle limiting
of the inductor current. If the output voltage drops during the current limiting interval, causing the FB voltage to fall under 84% of the internal reference, the device enters the hiccup mode, shutting down the output. After a fixed period, the device will try to re-enable the output. If the short-circuit condition still exists, it will shut down the output again, repeating the whole process until the short-circuit condition disappears. The hiccup mode greatly reduces the short-circuit current, protecting the device when the output is shorted to ground. This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. 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.
Features overview
Development board
Clicker 4 for STM32F3 is a compact development board designed as a complete solution, you can use it to quickly build your own gadgets with unique functionalities. Featuring a STM32F302VCT6, four mikroBUS™ sockets for Click boards™ connectivity, power managment, and more, it represents a perfect solution for the rapid development of many different types of applications. At its core, there is a STM32F302VCT6 MCU, a powerful microcontroller by STMicroelectronics, based on the high-
performance Arm® Cortex®-M4 32-bit processor core operating at up to 168 MHz frequency. It provides sufficient processing power for the most demanding tasks, allowing Clicker 4 to adapt to any specific application requirements. Besides two 1x20 pin headers, four improved mikroBUS™ sockets represent the most distinctive connectivity feature, allowing access to a huge base of Click boards™, growing on a daily basis. Each section of Clicker 4 is clearly marked, offering an intuitive and clean interface. This makes working with the development
board much simpler and thus, faster. The usability of Clicker 4 doesn’t end with its ability to accelerate the prototyping and application development stages: it is designed as a complete solution which can be implemented directly into any project, with no additional hardware modifications required. Four mounting holes [4.2mm/0.165”] at all four corners allow simple installation by using mounting screws. For most applications, a nice stylish casing is all that is needed to turn the Clicker 4 development board into a fully functional, custom design.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M4
MCU Memory (KB)
256
Silicon Vendor
STMicroelectronics
Pin count
100
RAM (Bytes)
40960
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the CLICKER 4 for STM32F302VCT6 as your development board.
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 Buck 9 Click driver
Key functions:
buck9_set_device_mode- This function enables and disables output of this board
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 Buck 9 Click Example.
*
* # Description
* Demo application shows basic usage of Buck 9 Click.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Configuring Clicks and log objects.
* Settings the Click in the default configuration.
*
* ## Application Task
* Enable and Disable device every 5 seconds.
*
* @author Stefan Ilic
*
*/
#include "board.h"
#include "log.h"
#include "buck9.h"
static buck9_t buck9; /**< Buck 9 Click driver object. */
static log_t logger; /**< Logger object. */
void application_init ( void ) {
log_cfg_t log_cfg; /**< Logger config object. */
buck9_cfg_t buck9_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.
buck9_cfg_setup( &buck9_cfg );
BUCK9_MAP_MIKROBUS( buck9_cfg, MIKROBUS_1 );
if ( buck9_init( &buck9, &buck9_cfg ) == DIGITAL_OUT_UNSUPPORTED_PIN ) {
log_error( &logger, " Application Init Error. " );
log_info( &logger, " Please, run program again... " );
for ( ; ; );
}
log_info( &logger, " Application Task " );
}
void application_task ( void ) {
buck9_set_device_mode ( &buck9, BUCK9_DEVICE_ENABLE );
log_printf(&logger, "Output:\t ENABLED\r\n");
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
buck9_set_device_mode ( &buck9, BUCK9_DEVICE_DISABLE );
log_printf(&logger, "Output:\t DISABLED\r\n");
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
}
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
Category:Buck
