Ensure optimal power delivery with LT3976 and PIC18F4685
Step down, Power up!
Published Nov 01, 2023
Click board™
BUCK Click
Dev Board
EasyPIC v8
Compiler
NECTO Studio
MCU
PIC18F4685
With its compact design and high efficiency, our step-down buck converter is the go-to solution for portable electronic devices, extending battery life while maintaining performance
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Hardware Overview
How does it work?
BUCK Click is based on the LT3976, a buck switching regulator from Analog Devices that accepts a wide input voltage range of up to 40V and steps it down to 3.3V or 5V. BUCK Click communicates with the target microcontroller over the following pins on the mikroBUS™ line: PWM, INT, RS, CS. The LT3976 is an adjustable frequency monolithic buck-switching regulator that accepts a wide input voltage range of up to 40V. Low quiescent current design consumes only
3.3µA of supply current while regulating with no load. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping the output ripple below 15mV in a typical application. The LT3976 can supply up to 5A of load current and has current limit foldback to limit power dissipation during short-circuit. A low dropout voltage of 500mV is maintained when the input voltage drops below the programmed output voltage, such as during an automotive cold
crank. There are two onboard screw terminals, one for connecting the external input supply and the other for the output. A multiplexer also chooses the resistor used for setting the switching frequency. The multiplexer is used for selecting one of the four different resistors. Each of these resistors, if selected, sets a different switching frequency from 0.4 to 1.6MHz.
Features overview
Development board
EasyPIC v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports many high pin count 8-bit PIC microcontrollers from Microchip, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, EasyPIC v8 provides a fluid and immersive working experience, allowing access anywhere and under any
circumstances at any time. Each part of the EasyPIC v8 development board contains the components necessary for the most efficient operation of the same board. In addition to the advanced integrated CODEGRIP programmer/debugger module, which offers many valuable programming/debugging options and seamless integration with the Mikroe software environment, the board also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector.
Communication options such as USB-UART, USB DEVICE, and CAN are also included, including the well-established mikroBUS™ standard, two display options (graphical and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from the smallest PIC MCU devices with only eight up to forty pins. EasyPIC v8 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.
Microcontroller Overview
MCU Card / MCU
Architecture
PIC
MCU Memory (KB)
96
Silicon Vendor
Microchip
Pin count
40
RAM (Bytes)
3328
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the EasyPIC v8 as your development board.
Track your results in real time
Application Output
After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.
Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.
In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".
The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.
Software Support
Library Description
This library contains API for BUCK Click driver.
Key functions:
buck_switch_frequency- Setting the switching frequency functionbuck_set_mode- Select buck mode (Disable / Enable)buck_get_power_good- Get state internal comparator function
Open Source
Code example
This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.
/*!
* \file
* \brief BUCK Click example
*
* # Description
* The demo application displays frequency change and voltage
* regulation using a BUCK 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
* This is a example which demonstrates the use of Buck Click board.
* Checks if it has reached the set output voltage and sets
* a different frequency to the LT3976 chip every 5 sec.
*
* \author Katarina Perendic
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "buck.h"
// ------------------------------------------------------------------ VARIABLES
static buck_t buck;
static log_t logger;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
buck_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.
buck_cfg_setup( &cfg );
BUCK_MAP_MIKROBUS( cfg, MIKROBUS_1 );
buck_init( &buck, &cfg );
Delay_ms( 100 );
buck_device_reset( &buck );
buck_default_cfg( &buck );
}
void application_task ( void )
{
// Task implementation.
if ( buck_get_power_good( &buck ) == 1 )
{
log_info( &logger, "---- Power good output voltage! ----" );
}
Delay_ms( 1000 );
log_info( &logger, "---- Switching frequency 400kHz! ----" );
buck_switch_frequency( &buck, BUCK_FREQ_400KHz );
Delay_ms( 5000 );
log_info( &logger, "---- Switching frequency 800kHz! ----" );
buck_switch_frequency( &buck, BUCK_FREQ_800KHz );
Delay_ms( 5000 );
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
