The Original LM2576HVT-ADJ High-Voltage Adjustable Step-Down (Buck) Switch Mode Voltage Regulator is a monolithic integrated circuit manufactured by Texas Instruments / National Semiconductor / ON Semiconductor, designed for high-efficiency DC-DC step-down power conversion. Encapsulated in a classic 5-lead TO-220 (TO-220-5 / Straight Leads) power package with a metal mounting tab, the "HV" (High Voltage) variant supports an extended input voltage range up to 60V DC (with a 65V absolute maximum rating) and is capable of delivering up to a 3.0A continuous load with excellent line and load regulation. Operating at a fixed internal switching frequency of 52 kHz, the adjustable output can be set between 1.23V and 57V using a simple two-resistor feedback divider. Featuring internal frequency compensation, cycle-by-cycle current limiting, thermal shutdown, and TTL-compatible shutdown control, the LM2576HVT-ADJ is widely used in high-voltage industrial machinery supplies, 24V/36V/48V battery systems, solar charge controllers, telecom equipment, and high-power LED driver modules.

Specifications

• Part Number / Model: LM2576HVT-ADJ / LM2576HVT-ADJ/NOPB (High Voltage Adjustable Version)
• Manufacturer: Texas Instruments / National Semiconductor / ON Semiconductor
• Regulator Topology: Step-Down (Buck) Switching DC-DC Converter
• Package Type: TO-220
• Adjustable Output Voltage Range (Vout): 1.23V to 57V DC (±4% max tolerance over line, load, and temperature)
• Internal Reference Voltage (Vref): Typ. 1.230V / Range 1.217V to 1.243V (at 25°C)
• Maximum Continuous Output Current (Iout): 3.0 A
• Input Voltage Range (Vin): 4.0V to 60V DC (Continuous) / 65V DC (Absolute Maximum Rating)
• Internal Oscillator / Switching Frequency (fosc): Typ. 52 kHz (±10% / 47 kHz to 58 kHz)
• Saturation Voltage (Vsat): Typ. 1.4V / Max. 1.8V (at Iout = 3A)
• Typical Conversion Efficiency: 75% to 88% (depending on Vin, Vout, and load current)
• Quiescent Current (Operating): Typ. 5.0 mA / Max. 10.0 mA (Feedback = 1.3V, Not Switching)
• Standby Quiescent Current: Typ. 50 µA / Max. 200 µA (when ON/OFF pin is pulled HIGH)
• Current Limit Threshold: Typ. 4.2 A / Range 3.5 A to 6.5 A (Cycle-by-cycle current limit)
• ON/OFF Logic Threshold Voltage: Low (Regulator ON): < 0> 2.0V
• Operating Junction Temperature (Tj): -40°C to +125°C
• Storage Temperature Range (Tstg): -65°C to +150°C
• Thermal Resistance, Junction-to-Case (Rth(j-c)): ~2°C/W
• Thermal Resistance, Junction-to-Ambient (Rth(j-a)): ~65°C/W (Free air without heatsink)
• Pinout Configuration (TO-220-5 - Front View, Metal Tab at Back, Leads Pointing Down):
  • Pin 1 (Left): VIN (Input Supply Voltage, 4V to 60V)
  • Pin 2: OUTPUT (Switching Node / Inductor Drive Output)
  • Pin 3: GROUND & Metal Tab (System Power Ground)
  • Pin 4: FEEDBACK (Output Voltage Sense / Resistor Divider Input)
  • Pin 5 (Right): ON/OFF (Active-Low Enable: Connect to GND for normal operation; pull HIGH to shut down)
  • Metal Mounting Tab: Internally tied to Pin 3 (Ground)

Features

• High 60V Continuous Input Rating (HV Series): Safely operates from high-voltage 24V, 36V, and 48V DC buses, telecom -48V converters, and unregulated solar panels without risk of breakdown from voltage transients.
• Full 3.0A Output Capability: Delivers up to 3.0A of continuous load current with high efficiency, drastically cutting heat dissipation compared to linear regulators like the LM317HV.
• Wide Adjustable Output Range (1.23V to 57V): Standard two-resistor feedback divider configures the output voltage precisely for 5V, 9V, 12V, 18V, 24V, 36V, or 48V auxiliary circuits.
• Standard TO-220 Through-Hole Package: Heavy-duty metal tab allows easy mounting onto standard extruded heatsinks for high ambient temperature and heavy continuous load environments.
• Logic-Level ON/OFF Shutdown: Dedicated Pin 5 enables external microcontrollers or supervisory circuits to toggle power or enter an ultra-low 50µA sleep mode.
• Comprehensive Integrated Protections: Includes cycle-by-cycle peak current limit, output short-circuit frequency foldback, and thermal overload shutdown.

Common Applications

• 48V & 36V Battery Step-Down Converters: High-efficiency conversion for e-bikes, golf carts, robotic rovers, and solar battery storage systems down to 12V or 5V logic rails.
• Industrial Automation (24V/48V Rails): Stepping down industrial 24V/48V PLC and cabinet power supplies to 5V/3.3V for embedded controllers.
• High-Voltage DC-DC Pre-Regulators: Efficient front-end converter dropping high DC supply voltages before low-noise LDO stages.
• Telecom & Networking Power Supplies: Auxiliary power generation from -48V / +48V communication power buses.
• High-Power LED Constant Voltage Modules: Step-down power supplies for high-output LED arrays and lighting fixtures.

Usage Tips

• Feedback Resistor Divider Calculation: The output voltage is calculated using Vout = 1.23V × (1 + R2 / R1), where R1 is connected between Pin 4 (Feedback) and GND, and R2 is connected between Vout and Pin 4. A recommended standard value for R1 is **1.0kΩ to 5.0kΩ** (1% tolerance recommended).
  • For 5.0V Output (with R1 = 1.0kΩ): R2 = 1.0kΩ × (5.0 / 1.23 - 1) ≈ 3.06kΩ (Standard 3.09kΩ 1%).
  • For 12.0V Output (with R1 = 1.0kΩ): R2 = 1.0kΩ × (12.0 / 1.23 - 1) ≈ 8.75kΩ (Standard 8.66kΩ or 8.87kΩ 1%).
  • For 24.0V Output (with R1 = 1.0kΩ): R2 = 1.0kΩ × (24.0 / 1.23 - 1) ≈ 18.51kΩ (Standard 18.7kΩ 1%).
• Catch Diode Selection (Critical for HV): For input voltages above 30V, ensure you use a **fast-recovery Schottky diode rated for at least 3A and 60V–100V (e.g., SS36, SS310, MBR360, or MBR3100)** connected from Pin 2 (Cathode) to Pin 3 GND (Anode). Standard silicon rectifier diodes (such as 1N4007 or 1N5408) must never be used.
• Inductor Selection: Use a power inductor rated for at least 3.5A to 4.0A saturation current with an inductance between **68µH and 220µH** (chosen according to the LM2576HV inductor selection curves for your specific Vin, Vout, and load).
• Input & Output Capacitor Voltage Ratings: When operating near 48V or 60V inputs, use high-grade low-ESR electrolytic capacitors rated for **63V, 80V, or 100V** on the input (e.g., 100µF 100V) and appropriately rated low-ESR capacitors on the output.
• Heatsink Mounting: When drawing continuous currents above 1.5A or dropping high differential voltages (e.g., 48V down to 5V at 2A), mount the TO-220 package to an aluminum heatsink. Because the metal tab is internally connected to Pin 3 (GND), it can often be grounded directly to chassis or PCB thermal planes without an insulating mica washer.

Datasheet