Achieve ultra-stable voltage references with the REF34xx and PIC18F57Q43
High-precision CMOS voltage reference solution
Published Apr 21, 2025
Click board™
VREF Click
Dev. board
Curiosity Nano with PIC18F57Q43
Compiler
NECTO Studio
MCU
PIC18F57Q43
Ensure stable and precise voltage references for sensitive analog systems with ultra-low noise and drift
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Hardware Overview
How does it work?
VREF Click is based on the REF34xx, a high-precision CMOS voltage reference from Texas Instruments, designed to provide a stable and accurate voltage output in low-power and noise-sensitive applications. The REF34xx features a low temperature drift of just 6 ppm/°C and an initial accuracy of ±0.05%, ensuring consistent performance across varying environmental conditions. With a power consumption of less than 95µA and an ultra-low output noise of only 3.8μVp-p/V, the VREF Click is an ideal choice for high-resolution data acquisition systems where signal integrity is crucial. VREF Click is available in multiple versions to suit different design requirements: 2.5V (REF3425), 3V (REF3430), 3.3V (REF3433), and 4.096V (REF3440), with the 2.5V version as the default configuration. The device supports an output current of ±10mA and has a maximum zero load dropout voltage of just 100mV, while offering excellent long-term stability of 25ppm over 1000 hours. Its low output-voltage
hysteresis and minimal long-term drift further enhance system reliability. VREF Click is compatible with a wide range of ADC and DAC components, including the ADS1287, DAC8802, and ADS1112, and is commonly used in applications such as positive and negative voltage references and various data acquisition systems. This Click board™ is designed in a unique format supporting the newly introduced MIKROE feature called "Click Snap." Unlike the standardized version of Click boards, this feature allows the main chip area to become movable by breaking the PCB, opening up many new possibilities for implementation. Thanks to the Snap feature, the REF34xx can operate autonomously by accessing their signals directly on the pins marked 1-8. Additionally, the Snap part includes a specified and fixed screw hole position, enabling users to secure the Snap board in their desired location. VREF Click uses a single communication line - the EN (Enable) pin - to control the operational state of the
REF34xx voltage reference. When the EN pin is pulled HIGH, the device enters Active mode and functions normally, delivering a precise output voltage. Pulling the EN pin LOW places the device into a low-power Shutdown mode, in which the output becomes high impedance and the quiescent current drops to just 2µA, significantly reducing power consumption. For visual indication of the device’s status, the board includes a red LED labeled LD2, which lights up when the device is enabled. If desired, this LED can be disabled by cutting the NT1 trace on the PCB, allowing for even lower power usage in energy-sensitive applications. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. 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
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
VREF Click demo application is developed using the NECTO Studio, ensuring compatibility with mikroSDK's open-source libraries and tools. Designed for plug-and-play implementation and testing, the demo is fully compatible with all development, starter, and mikromedia boards featuring a mikroBUS™ socket.
Example Description
This example demonstrates the use of the VREF Click board by enabling and disabling its 2.5V reference output periodically. The application toggles the output every 3 seconds and logs the current state via UART.
Key functions:
vref_cfg_setup- This function initializes Click configuration structure to initial values.vref_init- This function initializes all necessary pins and peripherals used for this Click board.vref_enable_output- This function enables VREF output by setting the EN pin to high logic state.vref_disable_output- This function disables VREF output by setting the EN pin to low logic state.
Application Init
Initializes the logger and configures the VREF Click driver.
Application Task
Alternately enables and disables the voltage reference output with a 3-second delay, displaying the output state on the UART terminal.
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 VREF Click example
*
* # Description
* This example demonstrates the use of the VREF Click board by enabling and disabling
* its 2.5V reference output periodically. The application toggles the output every
* 3 seconds and logs the current state via UART.
*
* The demo application is composed of two sections:
*
* ## Application Init
* Initializes the logger and configures the VREF Click driver.
*
* ## Application Task
* Alternately enables and disables the voltage reference output with a 3-second delay,
* displaying the output state on the UART terminal.
*
* @author Stefan Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "vref.h"
static vref_t vref; /**< VREF Click driver object. */
static log_t logger; /**< Logger object. */
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
vref_cfg_t vref_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.
vref_cfg_setup( &vref_cfg );
VREF_MAP_MIKROBUS( vref_cfg, MIKROBUS_1 );
if ( DIGITAL_OUT_UNSUPPORTED_PIN == vref_init( &vref, &vref_cfg ) )
{
log_error( &logger, " Communication init." );
for ( ; ; );
}
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
log_printf( &logger, " VREF Output: Enabled\r\n" );
vref_enable_output ( &vref );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
log_printf( &logger, " VREF Output: Disabled\r\n\n" );
vref_disable_output ( &vref );
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:Linear
