Achieve some serious voltage step-down brilliance with MPQ8632 and PIC18F57Q43
Synchronous step-down magic!
Published Feb 13, 2024
Click board™
Buck 12 Click
Dev. board
Curiosity Nano with PIC18F57Q43
Compiler
NECTO Studio
MCU
PIC18F57Q43
Compact and versatile, our buck step-down converter is essential in portable devices, extending battery life and enhancing usability
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Hardware Overview
How does it work?
Buck 12 Click is based on the MPQ8632, a synchronous step-down converter from Monolithic Power Systems (MPS). This advanced integrated step-down converter requires a minimum number of external components readily available on the market. It utilizes a peak-current-mode control architecture, ensuring good efficiency and automatic switch-mode switching. The MPQ8632 buck converter features over-current, under-voltage, and thermal protection, making Buck 12 click a robust and reliable power supply solution. The feedback voltage on the FB pin determines the output voltage. The output voltage is set to 3.3V, making it usable with most embedded applications, allowing them to be powered from the same source, like the rest of the application, which may use a higher voltage for its operation. This is a common-case scenario in various field applications requiring a relatively high voltage, i.e., for servos, step motors, displays, and more. When there is an overload at the output, the low-side MOSFET will allow the inductor current to drop.
It will remain open until the current through the inductor falls below the limit. Suppose the FB voltage drops too much during the overload. In that case, the device enters the hiccup mode, which turns off the output power stage, discharges the soft-start capacitor, and automatically retries the soft-start. The MPQ8632 can automatically switch between different operating modes, depending on the current through the load. At very light loads, the device is operated in skip mode. In this mode, HS-FET turns on for a fixed interval determined by the one-shot on-timer. When the HS-FET turns off, the LS-FET turns on until the inductor current reaches zero. The LS-FET driver turns into a tri-state (high Z) whenever the inductor current reaches zero. This way, the device is idle while the light load consumes energy stored within the coil. This greatly improves the efficiency when a light load is used. This is also called discontinuous conduction mode (DCM). The MPQ8632 automatically switches to heavy load operation or continuous
conduction mode (CCM) when heavily loaded. In this mode, when VFB is below VREF, HS-FET turns on for a fixed interval determined by the one-shot on-timer. When the HS-FET turns off, the LS-FET turns on until the next period. In CCM operation, the switching frequency is fairly constant and called PWM mode. Packed in QFN casing (3X4mm), the MPQ8632 occupies a small area on the PCB. Combined with the low count of external components it requires, the MPQ8632 leaves enough space for an additional IC to be used. This click uses the MCP3202, a Dual Channel 12-Bit A/D Converter which uses the SPI interface from Microchip. It allows monitoring of the input and output voltages over the SPI interface. This ADC is powered by the +5V mikroBUS™ power rail. The same voltage is used as a reference. The Click board™ itself requires an external power supply to be connected at the input terminal, labeled as VIN. The VOUT terminal provides the connected load with the regulated 3.3V voltage.
Features overview
Development board
PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive
mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI
GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.
Microcontroller Overview
MCU Card / MCU
Architecture
PIC
MCU Memory (KB)
128
Silicon Vendor
Microchip
Pin count
48
RAM (Bytes)
8196
You complete me!
Accessories
Curiosity Nano Base for Click boards is a versatile hardware extension platform created to streamline the integration between Curiosity Nano kits and extension boards, tailored explicitly for the mikroBUS™-standardized Click boards and Xplained Pro extension boards. This innovative base board (shield) offers seamless connectivity and expansion possibilities, simplifying experimentation and development. Key features include USB power compatibility from the Curiosity Nano kit, alongside an alternative external power input option for enhanced flexibility. The onboard Li-Ion/LiPo charger and management circuit ensure smooth operation for battery-powered applications, simplifying usage and management. Moreover, the base incorporates a fixed 3.3V PSU dedicated to target and mikroBUS™ power rails, alongside a fixed 5.0V boost converter catering to 5V power rails of mikroBUS™ sockets, providing stable power delivery for various connected devices.
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 Curiosity Nano with PIC18F57Q43 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 12 Click driver.
Key functions:
buck12_control- This function for enable or disable devicebuck12_get_channel_adc- This function reads ADC on the channelbuck12_get_voltage- This function gets voltage
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
* \brief Buck12 Click example
*
* # Description
* This demo application reads the voltage in [mV] at the input and output terminals.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Configuring clicks and log objects.
*
* ## Application Task
* Reads the voltage in [mV] at the input and output terminals.
* This data logs to the USBUART every 2 sec.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "buck12.h"
// ------------------------------------------------------------------ VARIABLES
static buck12_t buck12;
static log_t logger;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
buck12_cfg_t cfg;
/**
* 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.
buck12_cfg_setup( &cfg );
BUCK12_MAP_MIKROBUS( cfg, MIKROBUS_1 );
buck12_init( &buck12, &cfg );
buck12_control( &buck12, BUCK12_ENABLE );
Delay_ms( 2000 );
}
void application_task ( void )
{
float voltage;
voltage = buck12_get_voltage( &buck12, BUCK12_INPUT_VOLTAGE );
log_printf( &logger, "* Vin : %f mV \r\n ", voltage);
voltage = buck12_get_voltage( &buck12, BUCK12_OUTPUT_VOLTAGE );
log_printf( &logger, "* Vout : %f mV \r\n ", voltage);
log_printf( &logger, "--------------------------\r\n");
Delay_ms( 2000 );
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
