DC Buck Converter LM2596 DC DC Power Module LED Display Power Supply Adjustable Step-Down Converter 4.0~40 V Voltage Regulator 1. Features a voltmeter display with ±0.1V accuracy and a measurement range of 4–40V. (Note: Voltmeter does not operate or display when input voltage is below 4V.) 2. Equipped with large 5x5 touch buttons to switch between input and output voltage measurement. An indicator light shows which voltage is being measured. By default, the digital display shows input voltage with the IN indicator lit. Pressing the button switches to output voltage display with the OUT indicator lit. Settings are retained even after power cycling. 3. Voltmeter can be turned off by long-pressing the switch for more than 1 second but less than 4 seconds. A short press reactivates the voltmeter. 4. Includes screw terminal blocks for easy connection without soldering, while maintaining wire bonding points. (Input voltage must be at least 1V higher than the desired output voltage.) 5. Operates at a 150kHz internal oscillation frequency, featuring second-generation switching regulator technology for low power consumption and high efficiency. 6. Input端 includes diode protection to prevent damage from reverse polarity connection. 7. Built-in overheat and short-circuit protection. (For loads above 15W, additional heat dissipation is recommended.) How to Calibrate Output Voltage (or Input Voltage): Step 1: Press the right button until the "OUT" ("IN") LED lights up, indicating the displayed voltage value is from the output (input). Press and hold the right button for more than 2 seconds, then release. The display and "OUT" ("IN") LED will flash simultaneously, entering calibration mode. Step 2: Press the right button to increase the voltage value in small increments; press the left button to decrease it. Since each step is less than 0.1V, multiple presses (1–5 times) may be required to observe a 0.1V change on the display. The number of presses needed depends on the current voltage level—higher voltages require fewer presses per 0.1V change. Step 3: Press and hold the right button for more than 2 seconds, then release to exit calibration mode. All settings are saved automatically. Specifications: Input Voltage: 2.5V–40V Output Voltage: 1.25V–37V (adjustable) Output Current: Up to 3A Conversion Efficiency: Up to 92% Output Ripple: Low noise design