This guide covers setup, adjustment, and use of the XL4015 5A CC/CV Step-Down Buck Converter Module with LED Display. This module steps down a higher DC voltage to a lower one with adjustable Constant Voltage (CV) and Constant Current (CC) control, and features a built-in digital meter that displays output voltage, current, and power. It includes both screw terminal and USB output connections.
Whether you're charging batteries, driving LEDs, powering a project, or building a bench power supply, this guide will walk you through everything you need to know — even if you're new to electronics.
💡 What Is This Module?
This module is a DC-DC buck (step-down) converter — it takes a higher DC input voltage and converts it to a lower DC output voltage efficiently. Unlike a simple resistor or linear regulator that wastes excess voltage as heat, a buck converter uses high-frequency switching (180 KHz) to convert voltage with up to 96% efficiency, meaning very little energy is wasted.
What Makes This Module Special
This isn't just a basic voltage regulator. It has three key capabilities that make it far more versatile:
- Constant Voltage (CV) Mode: The module maintains a steady output voltage regardless of how much current the load draws (up to the set current limit). This is how most power supplies work — you set 5V, and it stays at 5V whether your circuit draws 100mA or 3A.
-
Constant Current (CC) Mode: The module limits the output current to a set value, regardless of the load. If the load tries to draw more current than the CC limit, the module automatically reduces the output voltage to maintain the set current. This is essential for:
- Charging batteries safely (prevents overcurrent damage)
- Driving LEDs (LEDs need current limiting, not voltage limiting)
- Protecting sensitive circuits from current surges
- Built-in Digital Meter: The LED display shows real-time output voltage (V), output current (A), and output power (W), plus input voltage. A push button cycles through the display modes. This eliminates the need for an external multimeter during setup and monitoring.
How CV and CC Work Together
The module automatically switches between CV and CC modes based on the load:
- Light load (CV mode): When the load draws less current than the CC limit, the module operates in Constant Voltage mode — output voltage stays at the set value, and current varies with the load.
- Heavy load (CC mode): When the load tries to draw more current than the CC limit, the module switches to Constant Current mode — current stays at the set limit, and voltage drops as needed to maintain that current.
Example — Charging a lithium-ion battery: You set CV to 4.2V and CC to 1A. Initially, the discharged battery looks like a heavy load, so the module operates in CC mode, pushing a steady 1A into the battery while voltage gradually rises. When the battery voltage reaches 4.2V, the module transitions to CV mode, holding 4.2V while the current gradually tapers off as the battery reaches full charge.
⭐ Features
- Wide input voltage range: 8V to 36V DC
- Adjustable output voltage: 1.2V to 34V DC (must be at least 1.5V below input)
- Adjustable output current: 0A to 5A peak (4A maximum continuous recommended)
- Dual control modes: Constant Voltage (CV) and Constant Current (CC) with automatic crossover
- Built-in LED display: Shows input voltage, output voltage (V), output current (A), and output power (W)
- Display mode button: Push button cycles through display readings
- Dual output connections: Screw terminals and USB Type-A port
- Two adjustment potentiometers: One for voltage (CV), one for current (CC)
- High efficiency: Up to 96% conversion efficiency (switching at 180 KHz)
- Built-in protections: Over-temperature, over-current, and short-circuit protection
- Reverse polarity protection: On the input side
- LED indicator: Shows CC/CV operating mode
📋 Specifications
| Parameter | Value |
|---|---|
| Converter IC | XL4015 |
| Converter Type | DC-DC Buck (Step-Down) |
| Input Voltage | 8V – 36V DC |
| Output Voltage | 1.2V – 34V DC (adjustable) |
| Output Current | 0 – 5A peak / 4A continuous |
| Minimum Dropout | ~1.5V (input must be ≥1.5V above output) |
| Conversion Efficiency | Up to 96% |
| Switching Frequency | 180 KHz (fixed) |
| Control Modes | Constant Voltage (CV) / Constant Current (CC) |
| Voltage Adjustment | Multi-turn potentiometer (CV-ADJ) |
| Current Adjustment | Multi-turn potentiometer (CC-ADJ) |
| Display | LED digital meter (V, A, W, input V) |
| Output Connections | Screw terminals + USB Type-A port |
| Input Connections | Screw terminals (IN+ / IN−) |
| Protections | Over-temperature, over-current, short-circuit, reverse polarity (input) |
| Operating Temperature | −40°C to +85°C |
| Board Dimensions | ~65mm × 40mm × 20mm |
📌 Board Layout
Connectors & Controls
| Component | Location | Function |
|---|---|---|
| IN+ / IN− | Input screw terminals | Connect your DC power supply here (8–36V). Observe polarity! |
| OUT+ / OUT− | Output screw terminals | Connect your load (battery, LED, circuit, etc.) |
| USB Port | Output USB Type-A | Alternative output for USB-powered devices (voltage must be set to 5V for standard USB devices) |
| CV-ADJ | Potentiometer (multi-turn) | Adjusts the output voltage (Constant Voltage setpoint) |
| CC-ADJ | Potentiometer (multi-turn) | Adjusts the output current limit (Constant Current setpoint) |
| Display Button | Push button near display | Cycles the LED display through: Input Voltage → Output Voltage → Output Current → Output Power |
| LED Display | Top of board | Shows real-time readings for the selected parameter |
| CC/CV LED | Near display | Indicates current operating mode (CC or CV) |
Identifying the Potentiometers
The two potentiometers are typically labeled on the board's silkscreen:
- CV-ADJ (or V-ADJ): Controls the output voltage. Turning clockwise typically increases voltage.
- CC-ADJ (or I-ADJ): Controls the output current limit. Turning clockwise typically increases the current limit.
Tip: These are multi-turn potentiometers, meaning you may need to turn them many rotations to move through the full range. This gives you fine, precise control — but it also means you won't see immediate changes with a small turn. Be patient and turn slowly while watching the display.
XL4105 CC/CV Module Connector and Control Diagram
🔌 Initial Setup & Adjustment
⚠️ IMPORTANT: Always adjust the output voltage and current BEFORE connecting your load (battery, LED, circuit, etc.). Connecting a load before setting the correct output can damage your load or the module.
What You'll Need
- A DC power supply (8V–36V) — must be at least 1.5V higher than your desired output voltage
- A small Phillips or flathead screwdriver (for the potentiometers)
- A multimeter (recommended for verifying the display readings)
- Wire or cables appropriate for your current requirements
Step 1: Pre-Adjust Before Connecting Power (Safety First)
Before connecting any power source, turn the CV-ADJ potentiometer fully counter-clockwise to set the output voltage to its minimum. This ensures you won't accidentally output a high voltage when you first power up.
Step 2: Connect the Input Power Supply
- Connect your DC power supply's positive (+) wire to the IN+ screw terminal.
- Connect your DC power supply's negative (−) wire to the IN− screw terminal.
- Double-check polarity before turning on the power supply. While the module has reverse polarity protection, it's always best practice to verify.
- Turn on your power supply. The LED display should light up.
Step 3: Set the Output Voltage (CV)
- Press the display button until the display shows output voltage.
- With no load connected, slowly turn the CV-ADJ potentiometer clockwise to increase the output voltage.
- Watch the display and stop when you reach your desired output voltage.
- Recommended: Verify the output voltage with a multimeter connected to the OUT+ and OUT− terminals for accuracy.
Step 4: Set the Current Limit (CC)
Setting the current limit requires a temporary short-circuit method or a dummy load:
Method A: Short-Circuit Method (Simplest)
- First, turn the CV-ADJ potentiometer to set the output voltage to a low value (around 1–2V). This minimizes power dissipation during the short.
- Temporarily short the OUT+ and OUT− terminals together using a thick wire or your multimeter set to the Amps (A) range.
- The module will immediately enter CC mode (the CC LED should illuminate).
- Press the display button to show output current.
- Turn the CC-ADJ potentiometer to set your desired current limit.
- Remove the short and restore your desired output voltage using the CV-ADJ potentiometer.
Method B: Using a Multimeter in Series
- Set your multimeter to the DC Amps (A) range (use the 10A jack if available).
- Connect the multimeter in series between the OUT+ terminal and a dummy load (such as a power resistor).
- Adjust the CC-ADJ potentiometer while watching the multimeter reading.
- Set to your desired current limit.
Step 5: Connect Your Load
Once both voltage and current are set correctly:
- Turn off the input power supply.
- Connect your load to the OUT+ and OUT− screw terminals (or plug a USB device into the USB port if using 5V output).
- Turn the power supply back on.
- Use the display button to cycle through readings and verify everything is operating as expected.
📡 Using the LED Display
The built-in LED display is one of the most useful features of this module. It eliminates the need for an external multimeter during normal operation.
Display Modes
Press the push button to cycle through the following display modes:
| Press # | Display Shows | Unit | What It Means |
|---|---|---|---|
| 1 | Input Voltage | V | The voltage being supplied to the module's input terminals |
| 2 | Output Voltage | V | The voltage at the output terminals (what your load sees) |
| 3 | Output Current | A | The current being drawn by your load right now |
| 4 | Output Power | W | The power being delivered to your load (Voltage × Current) |
Note: The display readings are approximate. For critical applications (especially battery charging), verify with a calibrated multimeter.
CC/CV Indicator LED
- CV mode (normal operation): The module is regulating voltage. Current varies with load demand.
- CC mode (current limiting active): The module is limiting current. Voltage drops as needed to maintain the set current. The CC indicator LED illuminates.
💡 Application Guides
Application 1: Battery Charger (Li-ion / LiFePO4 / Lead-Acid)
This module makes an excellent battery charger because the CC/CV charging profile is exactly what most rechargeable batteries require.
Li-ion / LiPo Battery Charging (Single Cell)
| Parameter | Setting |
|---|---|
| Output Voltage (CV) | 4.20V (standard) or 4.35V (high-voltage cells) — do not exceed your cell's rated voltage |
| Output Current (CC) | 0.5C to 1C of battery capacity (e.g., 1A for a 2000mAh cell) |
| Input Voltage | At least 5.7V (4.2V + 1.5V dropout) |
LiFePO4 Battery Charging (Single Cell)
| Parameter | Setting |
|---|---|
| Output Voltage (CV) | 3.65V |
| Output Current (CC) | 0.5C to 1C of battery capacity |
| Input Voltage | At least 5.15V |
12V Lead-Acid Battery Charging
| Parameter | Setting |
|---|---|
| Output Voltage (CV) | 14.4V (bulk charge) / 13.8V (float charge) |
| Output Current (CC) | 10% of battery Ah rating (e.g., 1A for a 10Ah battery) |
| Input Voltage | At least 15.9V |
⚠️ Important Battery Charging Notes:
- This module does NOT have automatic charge termination (auto-cutoff). It will continue to hold the set voltage on the battery indefinitely. For lithium batteries, this means you should monitor charging and disconnect manually when current drops to ~0.05C, or add an external auto-cutoff circuit.
- Always verify the voltage setting with a multimeter before connecting a battery.
- Never leave lithium battery charging unattended without proper safety monitoring.
- Ensure your input power supply can deliver enough current for the charging rate you've set.
Application 2: LED / Laser Diode Driver
LEDs and laser diodes are current-driven devices — they need a constant current source, not a constant voltage source. This module's CC mode is perfect for this.
- Set the CV-ADJ to a voltage slightly above the LED's forward voltage (e.g., for a 3.2V LED, set CV to about 3.5–4V).
- Set the CC-ADJ to the LED's rated continuous current (e.g., 350mA for a typical 1W LED, 700mA for a 3W LED).
- The module will operate in CC mode, delivering a steady current to the LED regardless of temperature-related voltage changes.
For LED strips: Set CV to the strip's rated voltage (usually 12V or 24V) and CC to the strip's maximum current draw. The module will operate in CV mode for strips since they have built-in current-limiting resistors.
Application 3: Bench Power Supply
This module can serve as a simple adjustable bench power supply with built-in metering:
- Connect a suitable DC power supply (e.g., a 24V or 36V laptop adapter) to the input.
- Adjust CV-ADJ to your desired output voltage.
- Set CC-ADJ to a safe current limit for your work (e.g., 1A for general prototyping).
- Use the screw terminals or USB port to power your projects.
- Monitor voltage, current, and power on the built-in display.
Application 4: USB Charger / 5V Power Supply
- Set the output voltage to exactly 5.0V using the CV-ADJ potentiometer.
- Set the current limit to your desired maximum (e.g., 2A for phone charging).
- Plug USB devices directly into the onboard USB Type-A port.
- You can also use the screw terminals simultaneously for non-USB loads.
Note: The USB port on this module provides power only — it does not support USB data communication. Some devices that require USB data negotiation for fast charging may only charge at a reduced rate.
Application 5: Solar Panel Voltage Regulator
Solar panels output variable voltage depending on sunlight conditions. This module can regulate the output to a stable voltage for charging batteries or powering equipment:
- Connect the solar panel to the input terminals (ensure the panel's open-circuit voltage does not exceed 36V).
- Set CV to your battery's charging voltage.
- Set CC to a safe charging current for your battery.
- The module will regulate the fluctuating solar panel output to a steady voltage and current.
🔋 USB Output
The onboard USB Type-A port provides an alternative output connection for USB-powered devices.
Key Points
- The USB port outputs the same voltage as the screw terminals — it is NOT automatically regulated to 5V. You must set the output voltage to 5.0V manually if you want standard USB voltage.
- The USB port is power-only (no data lines). It provides 5V and GND connections only.
- Both the USB port and screw terminals are active simultaneously — they share the same output.
- ⚠️ WARNING: If you set the output voltage above 5.25V and plug in a USB device, you may damage the device. Always verify the output voltage before connecting USB devices.
🛠️ Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Display doesn't light up | No input power, reversed polarity, or input voltage too low | Check input connections and polarity. Ensure input is at least 8V. |
| Output voltage is 0V or very low | CV potentiometer turned fully counter-clockwise | Slowly turn CV-ADJ clockwise while watching the display. |
| Output voltage won't reach desired level | Input voltage too low (insufficient dropout margin) | Input must be at least 1.5V higher than desired output. Increase input voltage. |
| Output voltage drops under load | Module is in CC mode (current limit reached) | Check the CC indicator LED. Increase the CC-ADJ setting or reduce the load. |
| Module gets very hot | High current draw, insufficient dropout, or poor ventilation | Add a heatsink or small fan. Reduce current draw. Increase input voltage to improve efficiency (but don't exceed 36V). |
| Output current is lower than expected | CC limit set too low, or input supply can't deliver enough current | Increase CC-ADJ setting. Verify your input power supply can deliver the required current. |
| Display shows incorrect readings | Normal — display is approximate | Use a calibrated multimeter for precise measurements. The display is for monitoring, not precision measurement. |
| USB device won't charge or charges slowly | Output voltage not set to 5V, or device requires data line negotiation | Verify output is exactly 5.0V. Some devices (especially newer phones) require USB data negotiation for fast charging, which this module doesn't support. |
| Potentiometer has no effect | Multi-turn pot — needs many rotations | These are multi-turn potentiometers. Keep turning slowly — it may take 10–20 full rotations to move through the full range. |
| Module shuts down intermittently | Over-temperature protection activating | Reduce load current, add heatsink/fan, or increase input voltage to improve efficiency. |
⚠️ Important Notes & Safety
- Always set voltage and current BEFORE connecting your load. This is the single most important rule for using this module safely.
- Input voltage must always be at least 1.5V higher than the output voltage. If the difference is too small, the module cannot regulate properly and output voltage will be unstable.
- Do not exceed 36V input. Exceeding the maximum input voltage will permanently damage the XL4015 IC.
- Maximum continuous current is 4A. While the module can handle 5A peaks, sustained operation above 4A requires active cooling (heatsink + fan). Without cooling, limit continuous use to 3A for longest module life.
- This module does NOT have automatic battery charge termination. It will hold the set voltage on the battery indefinitely. For lithium batteries, monitor charging and disconnect when current tapers to near zero, or add an external auto-cutoff circuit.
- The USB port outputs whatever voltage is set on the module — it is NOT automatically 5V. Always verify before connecting USB devices.
- Use appropriate wire gauge for your current requirements. For 5A operation, use at least 18 AWG wire. For 3A, 20 AWG is sufficient.
- Add a fuse on the input side for safety, especially in permanent installations. A 7A fast-blow fuse is recommended.
- Ensure adequate ventilation. The module generates heat during operation, especially at higher currents. Do not enclose it in a sealed box without ventilation.
- Do not use this module in life-safety or medical applications. It is designed for hobby, educational, and general-purpose use.
🔋 Thermal Management
Heat is the enemy of efficiency and longevity. The XL4015 IC has built-in thermal shutdown protection, but it's better to manage heat proactively:
| Current Draw | Cooling Required |
|---|---|
| 0 – 2A | No additional cooling needed in most cases |
| 2A – 3A | Small adhesive heatsink recommended on the XL4015 IC |
| 3A – 4A | Heatsink required. Consider a small fan for enclosed installations. |
| 4A – 5A (peak) | Heatsink + active fan cooling required. Not recommended for sustained use. |
Tip: Efficiency is highest when the input-to-output voltage difference is moderate. For example, converting 12V to 5V is more efficient (less heat) than converting 36V to 5V at the same current. Choose an input voltage that is adequate but not excessively higher than your output.
📋 Quick Reference Card
| Parameter | Value |
|---|---|
| Input Voltage Range | 8V – 36V DC |
| Output Voltage Range | 1.2V – 34V DC |
| Max Output Current | 5A peak / 4A continuous |
| Minimum Dropout | ~1.5V |
| CV Potentiometer | Sets output voltage |
| CC Potentiometer | Sets current limit |
| Display Button | Cycles: Input V → Output V → Output A → Output W |
| USB Port | Power only, same voltage as screw terminals |
| Setup Rule #1 | ALWAYS set voltage & current BEFORE connecting load |
🛒 Where to Buy the XL4015 Module
You can purchase the XL4015 5A DC-DC Step-Down CC/CV Buck Converter Module directly from Envistia Mall:
1.2-34V 5A DC-DC Step-down CC/CV XL4015 Battery Charger LED Driver with Volt, Amp & Power Meter
📚 Additional Resources
Mastering the XL4015 Step-Down Converter with display: A simple Guide video by Electronix on Youtube:
This user guide is provided as a courtesy by Envistia Mall. While we strive for accuracy, this guide is provided "as is" without warranty of any kind. Envistia Mall is not responsible for any damage to equipment or injury resulting from the use of this information. Always follow proper safety precautions when working with electrical circuits. Specifications and features are based on manufacturer data and may vary between production batches. For the most current product information, please visit envistiamall.com.