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The LM2596 is a monolithic step-down (buck) switching regulator designed to efficiently convert a higher DC voltage into a stable lower DC output. It can deliver up to 3A of continuous load current, making it suitable for medium-power applications. Compared to linear regulators, it offers much higher efficiency, especially when operating with large input-to-output voltage differences.
This regulator operates at a fixed switching frequency of 150 kHz, allowing the use of smaller external components such as inductors and capacitors. It is available in fixed output versions (3.3V, 5V, and 12V) as well as an adjustable version. The device includes built-in current limiting, thermal shutdown protection, and low standby current to improve reliability and simplify power supply design.
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| Pin No. | Pin Name | Description |
| 1 | VIN | Input voltage pin. Connects to the unregulated DC supply (typically 4V to 40V). |
| 2 | VOUT (Switch Output) | Internal power switch output. Connects to the inductor in the buck converter circuit. |
| 3 | GND | Ground pin. Connected to system ground. |
| 4 | Feedback (FB) | Feedback pin. Used to set and regulate the output voltage through a resistor divider. |
| 5 | ON/OFF (EN) | Enable pin. Used to turn the regulator ON or OFF. Logic low enables operation; logic high shuts it down. |
• LM2576
• LM2675
• LM2676
• LM22675
• LM22676
• XL2596
• XL4015
• TPS5430
• TPS5420
The LM2596 block diagram shows how the regulator converts an unregulated DC input into a stable lower DC output using a buck converter structure. The input voltage enters through the VIN pin and passes through an internal 3.1 V regulator that powers the control circuitry. A 1.235 V band-gap reference provides a precise voltage reference for accurate regulation.
The feedback pin monitors the output voltage through an external resistor divider. This signal is compared with the internal reference by the error amplifier and comparator. The result controls a latch driven by a 150 kHz oscillator, which generates the switching pulses. These pulses drive the internal 3 A power switch, rapidly turning it ON and OFF to regulate energy transfer to the inductor.
When the switch turns OFF, current flows through the external diode and inductor to maintain output power. The IC also includes current limiting and thermal shutdown protection to prevent damage from overload or overheating. The ON/OFF pin allows external control to enable or disable the regulator.
| Parameter | Maximum Rating |
| Maximum Supply Voltage (VIN) | 45 V |
| ON/OFF Pin Input Voltage | −0.3 V to +VIN |
| Output Voltage to Ground (Steady-State) | −1.0 V |
| Power Dissipation (TO-220, 5-Lead) | Internally Limited |
| Thermal Resistance, Junction-to-Ambient (TO-220) | 65 °C/W |
| Thermal Resistance, Junction-to-Case (TO-220) | 5.0 °C/W |
| Power Dissipation (D2PAK) | Internally Limited |
| Thermal Resistance, Junction-to-Ambient (D2PAK) | 70 °C/W |
| Thermal Resistance, Junction-to-Case (D2PAK) | 5.0 °C/W |
| Storage Temperature Range | −65 °C to +150 °C |
| Minimum ESD Rating (HBM, C = 100 pF, R = 1.5 kΩ) | 2.0 kV |
| Lead Temperature (Soldering, 10 seconds) | 260 °C |
| Maximum Junction Temperature (TJ) | 150 °C |
• Adjustable Output Voltage (1.23 V – 37 V) - The LM2596 adjustable version allows you to set the output voltage using an external resistor divider. This makes it flexible for different applications, from low-voltage digital circuits to higher-voltage systems.
• Guaranteed 3.0 A Output Load Current - The regulator can supply up to 3 amperes of continuous output current. This makes it suitable for powering microcontrollers, motors, LED drivers, and other medium-power loads.
• Wide Input Voltage Range (Up to 40 V) - It supports input voltages up to 40 V, allowing it to operate in systems powered by batteries, industrial supplies, or automotive sources.
• 150 kHz Fixed Frequency Internal Oscillator - The built-in 150 kHz oscillator controls switching operation. This fixed frequency simplifies component selection and allows the use of smaller inductors and capacitors.
• TTL Shutdown Capability - The ON/OFF pin allows the regulator to be turned on or off using TTL logic signals, enabling remote control and power management.
• Low Power Standby Mode (Typical 80 µA) - When disabled, the device consumes very low standby current, helping reduce overall system power consumption.
• Thermal Shutdown and Current Limit Protection - Built-in protection circuits prevent damage during overload or overheating conditions, improving reliability and safety.
• Internal Loop Compensation - The internal compensation simplifies circuit design by reducing the need for complex external stabilization components.
• Moisture Sensitivity Level (MSL) = 1 - An MSL rating of 1 means the device is highly resistant to moisture during storage and soldering, improving manufacturing reliability.
• Pb-Free Packages Available - Lead-free versions are available, meeting environmental and RoHS compliance standards.
This LM2596 typical adjustable buck converter configuration that steps down a 12 V unregulated DC input to a stable 5 V output at up to 3 A. The input voltage enters the VIN pin, and the 100 µF input capacitor (CIN) filters noise and stabilizes the supply before it reaches the regulator.
Inside the LM2596, the internal switch rapidly turns ON and OFF to control energy transfer. The switching output at Pin 2 connects to the inductor (L1, 33 µH). When the switch turns ON, energy is stored in the inductor. When it turns OFF, current flows through the Schottky diode (D1, 1N5822), maintaining continuous current to the load.
The output capacitor (COUT, 220 µF) smooths the pulsed voltage into a steady DC output. The resistor divider network (R1 and R2) connects to the Feedback pin and sets the output voltage. The CFF capacitor improves stability and transient response. The ON/OFF pin allows the regulator to be enabled or disabled externally.
• DC-DC step-down (buck) power supplies
• Battery-powered systems
• Automotive power regulation
• Industrial control systems
• Embedded systems and microcontroller boards
• LED drivers
• Motor driver power supplies
• Telecom power modules
• Portable electronic devices
• Distributed power systems
• Post-regulation for switching power supplies
• Adjustable laboratory power supplies
The adjustable buck regulator is configured to produce a stable regulated output from an unregulated DC input between 8.5 V and 40 V. The input voltage is applied to the VIN pin, and the 100 µF input capacitor (CIN) helps reduce input ripple and noise.
The internal switching transistor drives the inductor (L1, 33 µH) at a fixed 150 kHz frequency. When the internal switch turns ON, energy is stored in the inductor. When it turns OFF, current flows through the Schottky diode (D1, 1N5822), maintaining continuous current to the load. The output capacitor (COUT, 220 µF) smooths the switching waveform into a stable DC output.
The output voltage is set using the resistor divider (R1 and R2) connected to the Feedback pin. The relationship is:
Vout = Vref × (1 + R2 / R1)
Where Vref is 1.23 V. The CFF capacitor improves stability and transient response. The ON/OFF pin allows external enable or shutdown control of the regulator.
| Feature | LM2596 | LM2576 | XL4015 | MP1584 | TPS5430 |
| Type | Non-synchronous Buck | Non-synchronous Buck | Non-synchronous Buck | Synchronous Buck | Non-synchronous Buck |
| Output Current | 3 A | 3 A | 5 A | 3 A | 3 A |
| Input Voltage Range | Up to 40 V | Up to 40 V | Up to 36 V | Up to 28 V | Up to 36 V |
| Output Voltage Range | 1.23 V – 37 V | 1.23 V – 37 V | 1.25 V – 32 V | 0.8 V – 20 V | 1.22 V – 31 V |
| Switching Frequency | 150 kHz | 52 kHz | 180 kHz | 1.5 MHz | 500 kHz |
| Efficiency | Moderate | Moderate | Good | High | Good |
| External Components | Moderate | Larger (low freq) | Moderate | Fewer (high freq) | Moderate |
| Package Type | TO-220, D2PAK | TO-220 | TO-220, modules | Small SMD | SOIC, SMD |
| Protection Features | Thermal, Current Limit | Thermal, Current Limit | Thermal, Current Limit | Thermal, OCP | Thermal, OCP |
| Typical Use | General-purpose buck | Older designs | Higher current loads | Compact designs | Industrial applications |
| Package Type | Description |
| TO-220 (5-Lead) | Through-hole package with good heat dissipation. Commonly used in power supply designs and easy to mount with a heatsink. |
| TO-263 (D2PAK, 5-Lead) | Surface-mount version of TO-220. Designed for automated PCB assembly with good thermal performance through PCB copper area. |
| TO-220V (Vertical Mount) | Vertical through-hole style used in applications requiring upright PCB mounting. |
| TO-220F (Fully Isolated) | Isolated tab version of TO-220, reducing the need for insulating hardware when mounting to a heatsink. |
TO-263 (D2PAK, 5-Lead):
ON Semiconductor (onsemi) is a major global semiconductor manufacturer with extensive experience in producing power management ICs, including the LM2596 series of switching regulators. Leveraging high-volume fabrication facilities, rigorous quality control standards, and advanced analog/mixed-signal design expertise, onsemi manufactures LM2596 regulators in industry-standard packages such as TO-220 and D2PAK to meet automotive, industrial, and consumer power requirements.
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