Buck 10 Click

This click offers very compact buck solution that requires only input and output capacitors on MPM3632C to achieve 3A of continuous output current. The MPM3632C operates at a fixed 3MHz switching frequency and constant-on-time (COT) control, and provide full protection features like OVP, OCP and thermal shutdown.

How does it work?

The step down DC-DC regulator used on this click board™ is the MPM3632C, a 18V 3A ultra-low profile DC-to-DC power module by Monolithic Power Systems (MPS). This IC is a valley current mode controlled power module, meaning that it has a faster response than the traditional peak current mode control, therefore it has better response to transients. This IC requires a minimal number of external components, which makes the whole device pretty robust and easy to work with.

The output voltage is determined by the feedback voltage on the FB pin. Buck 10 click is equipped with a voltage divider and an SMD jumper, labeled as OUT SEL. This jumper can be used to connect one of two available voltage divider resistors, allowing the output to be set to either 3.3V or 5V. These two voltages are the most commonly used in embedded development.

The over-current protection is based on cycle-by-cycle limiting of the inductor current. If the output voltage starts to drop during the current limiting interval, causing the FB voltage to drop 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.

Thanks to its ability to work with the high duty cycle of the internal switching PWM signal, the MPM3632C requires the input voltage to be only about 0.7V above the output voltage, in order to maintain the regulation. However, if the input voltage drops under 3.1V, the device will not be able to operate properly. Therefore, the under-voltage protection shuts down the device, as a protection measure. The under-voltage protection is disabled once the input voltage exceeds 3.6V. This small hysteresis of 0.5V prevents erratic behavior in border-cases.

The MPM3632C operates at very high switching frequency of 3 MHz, which allows a good compromise between the efficiency and the size of the device with no external coil needed and minimal number of other external components.

As mentioned before, the voltage of the power supply at the input terminal should stay within the range between 4V and 18V. However, if the output voltage is set to 5V, the voltage at the input should be approximately 5.7V to 6V at least, in order to provide a good regulation at the output.

Specifications

Pinout diagram

This table shows how the pinout on Buck 10 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	EN	Enable input
	NC	2	RST	INT	15	NC
	NC	3	CS	RX	14	NC
	NC	4	SCK	TX	13	NC
	NC	5	MISO	SCL	12	NC
	NC	6	MOSI	SDA	11	NC
Power supply	+3.3V	7	3.3V	5V	10	NC
Ground	GND	8	GND	GND	9	GND	Ground

Onboard  Settings and Indicators

Buck 10 click electrical specifications

Software support

We provide a library for the Buck 10 Click board on our LibStock page, as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.

Library Description

This library allows user to perform a control of the Buck 10 Click board. User can drive the control pin (EN) to turn ON/OFF the device and output voltage. For more details check documentation.

Key functions:

• void buck10_gpioDriverInit(T_BUCK10_P gpioObj) - Convert ADC value to Pressure data in mBar.
• T_BUCK10_RETVAL buck10_enable( T_BUCK10_STATE pwr_state ) - This function allows user to enable or disable the device.

Examples description

The application is composed of three sections :

• System Initialization - Initializes PWM control pin as output and USBUART A port for logging.
• Application Initialization - Initializes GPIO driver.
• Application Task - (code snippet) - Turns ON the Buck 10 for 10 seconds and after that turns OFF the device and output for 10 seconds, and then repeats the all operation. Also when a device state was changed, a message will be sent to the uart terminal. Note: Input voltage recommended range - from 4V to 18V Low-side valley current limit - from 3A to 3.9A Low-side negative current limit - (-2.5A) Output voltage - 3.3V or 5V

void applicationTask()
{
    buck10_enable( _BUCK10_ENABLE );
    mikrobus_logWrite( "** Buck 10 is enabled **", _LOG_LINE );
    Delay_ms( 10000 );
    
    buck10_enable( _BUCK10_DISABLE );
    mikrobus_logWrite( "** Buck 10 is disabled **", _LOG_LINE );
    Delay_ms( 10000 );
}

The full application code, and ready to use projects can be found on our LibStock page.

Other mikroE Libraries used in the example:

• UART

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. The terminal available in all MikroElektronika compilers, or any other terminal application of your choice, can be used to read the message.

MikroSDK

This click board is supported with mikroSDK - MikroElektronika 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.