Product Overview
The LM2596S-ADJ Adjustable DC-DC Buck Converter Module is a high-performance step-down switching regulator based on the industry-standard LM2596S-ADJ chip from Texas Instruments . This versatile module efficiently converts higher DC voltages (from 7V to 35V) into a lower, continuously adjustable output voltage ranging from 1.25V to 30V, making it an essential tool for powering a wide variety of electronic devices.
Unlike traditional linear voltage regulators that dissipate excess energy as heat, this switching regulator uses Pulse Width Modulation (PWM) technology at a fixed 150kHz switching frequency to achieve conversion efficiencies of up to 92% . This means it runs much cooler and wastes significantly less power, making it ideal for battery-powered or enclosed applications. The module is capable of delivering up to 3A of continuous output current, enough to power an Arduino, Raspberry Pi, high-power LED strips, or other 5V/12V logic systems.
The module features a simple three-terminal interface and an onboard precision potentiometer for adjusting the output voltage. This makes it a favorite among electronics hobbyists, educators, and professionals for creating custom power supplies, retrofitting old electronics, and developing IoT devices. The fixed 150kHz oscillator frequency allows for smaller-sized filter components than what would be needed with lower frequency switching regulators .
Key Features
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Adjustable Output Voltage: Continuously adjustable output from 1.25V to 30V via an onboard precision potentiometer, allowing you to set exactly the voltage your project needs
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High-Efficiency Step-Down Conversion: Utilizes the LM2596S-ADJ switching regulator to achieve up to 92% efficiency, minimizing power loss and heat generation compared to linear regulators
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Wide Input Voltage Range: Accepts DC input from 7V to 35V (chip supports up to 40V), making it compatible with common 12V automotive, 24V industrial, and other higher voltage systems
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3A High Output Current: Capable of delivering up to 3A of output current. For loads above 2A, a heatsink is recommended to maintain optimal performance
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Fixed 150kHz Switching Frequency: Operates at a fixed 150kHz internal oscillator, allowing for smaller-sized filter components and lower output ripple
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Excellent Regulation: Features ±4% maximum output voltage tolerance over line and load conditions, ensuring stable power delivery
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Built-in Protection: Includes thermal shutdown and current limit protection (maximum switch current 7.5A) to safeguard the module and your connected devices under fault conditions
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Low Power Standby Mode: Features TTL shutdown capability with typically 80µA standby current consumption
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Requires Only 4 External Components: Simple design with minimal external components, making the module compact and reliable
Technical Specifications
Pinout & Interface Guide
The module is clearly labeled for easy wiring. Connection points include:
Input Side (Power Source)
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IN+ (VIN): Connect to the positive terminal of your DC power source (e.g., 12V battery, 24V power supply)
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IN- (GND): Connect to the negative terminal (ground) of your DC power source
Output Side (Load Connection)
User Controls
Status Indicators
Usage Guide
Wiring Instructions
IMPORTANT: Always disconnect the input power source before wiring or modifying connections. Reverse polarity may damage the module as there is no built-in reverse protection.
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Connect Input: Connect the positive wire of your DC power source to the IN+ terminal. Connect the negative wire to the IN- terminal.
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Set Initial Voltage: Before connecting your load, turn the blue potentiometer fully counter-clockwise to set the output voltage to its minimum. The factory default is often set to a higher voltage (around 18V).
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Power On & Adjust Voltage: Apply power. Use a multimeter on the output terminals. Slowly turn the potentiometer clockwise until you reach your desired output voltage (e.g., 5.0V for a Raspberry Pi, 12V for a fan).
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Connect Load: Turn off power, connect your device to OUT+ and OUT-, and re-apply power.
Example: Powering a 5V Device from a 24V Source
This is a classic and highly effective application for the LM2596S-ADJ module.
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Connect the 24V power supply’s positive rail to IN+ and the negative rail to IN-
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Connect a multimeter to the OUT+ and OUT- terminals
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Apply power and carefully adjust the potentiometer until the multimeter reads exactly 5.00V
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Turn off the power, connect your 5V device (e.g., Arduino, ESP8266) to the output terminals, and turn the power back on. The module will efficiently provide clean 5V power to your device.
Example: Building a Variable Bench Power Supply
You can easily create a low-cost variable bench power supply by combining this module with an AC-to-DC adapter.
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Use a 12V-24V DC power adapter as the input source
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Mount the LM2596S-ADJ module in a small enclosure
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Connect the module’s input to the adapter’s output
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Add binding posts to the enclosure connected to the module’s output terminals
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You now have a variable 1.25V-30V bench power supply for testing circuits and powering prototypes
Important Considerations
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Step-Down Only: This is a buck (step-down) converter only. The output voltage must always be lower than the input voltage. The input must be at least 1.5V higher than the desired output for stable regulation
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Heat Management: For loads above 2A, it is recommended to attach a small heatsink to the metal tab of the LM2596S-ADJ IC to ensure long-term reliability and prevent thermal shutdown. The maximum switch current is 7.5A
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Potentiometer Adjustment: The potentiometer has a wide adjustment range. It may require 10-15 turns before you see a significant change in the output voltage. If the output voltage cannot be adjusted, try turning the potentiometer counter-clockwise 20 or more turns
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Input/Output Differential: The input voltage must be at least 1.5V higher than the desired output voltage for proper regulation
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Catch Diode & Inductor Selection: For optimal performance, the catch diode should have a current rating equal to the maximum high-side current limit of the device (up to 7.5A), and the inductor needs a saturation current rating for this limit
Q: What is the difference between a buck converter and a boost converter?
A buck converter (step-down) decreases a higher input voltage to a lower output voltage (e.g., 24V to 5V). A boost converter (step-up) increases a lower input voltage to a higher output voltage. This module is a buck converter only
Q: Can this module increase voltage (boost)?
No. This is a buck (step-down) converter only. The output voltage must always be lower than the input voltage. The input must be at least 1.5V higher than the desired output for the regulator to function correctly
Q: What is the maximum output current I can draw from this module?
The module is rated for a maximum of 3A. For long-term reliability, it is recommended to stay within 2A – 2.5A, and a heatsink should be used for loads above 2A
Q: Can I use this module to power a Raspberry Pi or Arduino?
Yes. This module is excellent for powering 5V logic systems. By adjusting the output to 5.0V, you can power an Arduino, ESP8266, or Raspberry Pi from a higher voltage source like a 12V battery.
Q: Why is my output voltage not changing when I turn the potentiometer?
The potentiometer has a wide adjustment range. You may need to turn it 10-15 full rotations before you see a change in the output voltage. Keep turning it clockwise to increase the voltage. If it still doesn’t change, try turning it counter-clockwise 20 or more turns
Q: The module gets hot. Is this normal?
Some heat is normal, especially under high load. If it is too hot to touch, attach a heatsink to the LM2596S-ADJ IC. Also, ensure the input voltage is not excessively higher than the output, as a larger voltage differential generates more heat. Check that your diode and inductor are properly rated (diode should handle up to 7.5A)
Q: What is the input voltage range for this module?
The chip supports 4.5V to 40V DC, but for practical module use, a 7V to 35V range is recommended. For a stable regulated output, the input voltage must be at least 1.5V higher than your desired output voltage
Q: How accurate is the output voltage?
The LM2596S-ADJ adjustable version has a guaranteed ±4% tolerance on output voltage under specified input voltage and output load conditions
Q: What is the efficiency of this converter?
The conversion efficiency can reach up to 92% under optimal conditions, significantly higher than linear regulators which typically operate at 30-50% efficiency. At 12V input, 3V output, 3A load, efficiency is approximately 73%
Q: The module has power (LED is on) but there is no output voltage.
Follow this checklist:
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Check the potentiometer setting. It may be turned fully counter-clockwise (minimum voltage). Try turning it clockwise 10-15 turns while monitoring the output with a multimeter
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Check that there is no short circuit on the output terminals
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Verify that your input voltage is at least 1.5V higher than your target output voltage
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Ensure your load is not drawing more than 3A, triggering the current limit protection
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Check if the module is in thermal shutdown (let it cool down and retry)
Q: Can I connect the input in reverse?
No. Reversing the input polarity (connecting IN+ to negative and IN- to positive) will instantly destroy the module. Some modules include reverse polarity protection, but always double-check your wiring before applying power
Q: Can I use this module to charge a battery?
While the module can be used to charge batteries (e.g., setting output to 12.6V for a 3S Li-ion battery), it lacks a dedicated constant current (CC) charging profile. For unattended charging, it is safer to use a dedicated battery charger module that provides proper CC/CV charging.
Q: Why is my output voltage dropping under load?
This can happen if:
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The load current exceeds 3A (triggering current limit)
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The input voltage is too low or unstable (drops below the required minimum differential)
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The module is overheating and entering thermal throttling
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The output capacitor is insufficient or faulty
Q: What is the purpose of the feedback pin (FB)?
The feedback pin (FB) is used to set the output voltage through an external resistor divider network. For the adjustable version, the output voltage is programmed using two external resistors. The internal reference voltage is 1.230V
