DC Buck Converter LM2596 DC-DC Power Module LED Display Power Supply Adjustable Step-Down Converter 4.0~40V Voltage Regulator. Features a voltmeter display with ±0.1V accuracy, measuring range 4~40V. Note: When input voltage is below 4V, the onboard voltmeter will not function or display. 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. The selected mode is saved even after power cycle. The voltmeter can be turned off by long-pressing the button for more than 1 second but less than 4 seconds. To reactivate, simply press the button again. Includes terminal blocks for easy connection without soldering, while still providing wire bonding points. Input voltage must be at least 1V higher than the desired output voltage. Uses a 150kHz internal oscillation frequency, part of the second-generation switching regulator technology, offering low power consumption and high efficiency. Input端 features diode protection to prevent damage from reverse polarity connection. Includes overheat protection and short-circuit protection. For loads exceeding 15W, additional heat dissipation is recommended. Output Voltage (or Input Voltage) Calibration Steps: Step 1: Press the right button until the "OUT" ("IN") LED lights up, indicating the displayed value is output (input) voltage. 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 value in small increments; press the left button to decrease. Due to step resolution, multiple presses (1–5 times) may be required to observe a 0.1V change on the display. 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