Driver Circuit

Buck Converter Based IR Source Driver

A compact adjustable IR source driver designed around a MAX16977 buck converter for driving an infrared emitter with controlled output voltage/current.

The project covers schematic design, component selection, PCB layout, fabrication preparation, and hardware testing using KiCad.

Project Overview

The IR Source Driver was developed as a dedicated driver circuit for an IR source used in an infrared sensing/measurement setup.

The design uses a MAX16977 buck converter to provide an adjustable output suitable for the IR emitter. The PCB was designed in KiCad and prepared for PCB fabrication.

Key objectives

• Design a dedicated IR emitter driver
• Generate an adjustable regulated output
• Provide sufficient current capability for the IR source
• Design a compact PCB suitable for laboratory use
• Prepare manufacturing files for PCB fabrication
• Verify the assembled hardware through electrical measurements

Main Specifications

The actual operating point depends on the connected IR emitter, adjustment setting, and load conditions.

Circuit Overview

The main power path consists of:

9 V DC Input
     │
     ▼
┌───────────────┐
│ MAX16977      │
│ Buck Converter│
└───────┬───────┘
        │
        ▼
   Output Filter
        │
        ▼
 IR Source / Emitter

The design includes the switching regulator, power diode, compensation network, input/output filtering, adjustment circuitry, and output connector.

Major Components

Component values and part selections are documented in the project BOM.

Connectors

J1 — Input / Control Connector

The board is powered from a 9 V DC supply.

Output Adjustment

The output voltage/current is adjustable using VR1.

The driver was designed with an IR emitter operating around the required voltage and current range, with a maximum target current of approximately 175 mA.

The adjustment should be performed while monitoring the output with suitable measurement equipment and the intended load connected.

PCB Design

The PCB was designed using KiCad.

The design workflow included:

1. Schematic capture
2. Component selection
3. PCB footprint assignment
4. PCB placement
5. Routing
6. Power-path layout considerations
7. Design-rule checking
8. Gerber generation
9. PCB fabrication
10. Hardware assembly and testing

Manufacturing Files

The repository contains the design source files and, where applicable, fabrication outputs.

schematic/
    KiCad schematic

pcb/
    KiCad PCB layout

fabrication/
    Gerber files
    Drill files

bom/
    Bill of Materials

documentation/
    Design documentation

The original KiCad design files are retained so that the project can be opened and further modified in KiCad.

Testing

The assembled PCB was electrically tested using laboratory measurement equipment.

Testing included checking:

• Input supply
• Converter output
• Output adjustment
• Behaviour under load
• Voltage levels at important test points
• IR source drive operation

Measured values should be interpreted together with the connected load and test conditions.

Design Considerations

Several aspects were considered during the design:

Power regulation

The MAX16977 provides the switching regulation required to convert the 9 V input into the lower voltage required by the IR source.

Output filtering

Multiple output capacitors were used to provide output filtering and support transient load requirements.

Current capability

The output stage was designed around the required IR emitter current, with the target maximum current being approximately 175 mA.

PCB layout

The PCB layout considers the switching power path, component placement, grounding, and routing of the regulator circuitry.

Tools Used

• KiCad — Schematic and PCB design
• PCB fabrication service — PCB manufacturing
• Laboratory power supply / DC adapter
• Digital multimeter
• Oscilloscope / measurement equipment where required

Repository Structure

IR-Source-Driver/
│
├── README.md
├── LICENSE
│
├── schematic/
│   └── *.kicad_sch
│
├── pcb/
│   ├── *.kicad_pcb
│   └── *.kicad_pro
│
├── fabrication/
│   ├── gerbers/
│   └── drill/
│
├── bom/
│   └── BOM.csv
│
├── documentation/
│   └── *.pdf
│
└── images/
    ├── schematic.png
    ├── pcb_layout.png
    └── pcb_3d.png

Applications

The driver can be used as part of an IR measurement system where a controlled infrared source is required.

The board was developed as part of an experimental infrared sensing/measurement setup.

Future Improvements

Possible improvements include:

• Improved thermal management
• More precise closed-loop current regulation
• Additional protection features
• Improved output monitoring
• Dedicated test points
• Further PCB layout optimization
• Integration with a microcontroller-based measurement system

Author

Nitin Rajput

Electronics & Communication Engineering

Areas demonstrated

• Power electronics
• Buck converter design
• PCB design
• KiCad
• Component selection
• Hardware debugging
• Electrical testing
• Embedded hardware development

Disclaimer

This project is intended for engineering and educational documentation.

The IR emitter and power components should be operated within their specified electrical and thermal limits. Appropriate current limiting, measurement, and safety precautions should be used during hardware testing.