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Texas Instruments LM2576SX-ADJ/NOPB
- Part No.:
- LM2576SX-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2576SX-ADJ/NOPB.pdf
- Description:
- IC REG BUCK ADJ 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,420
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Product details
Overview
LM2576SX-ADJ/NOPB from Texas Instruments is a monolithic 3-A non-synchronous step-down DC-DC switching regulator in TO-263 (DDPAK) package, delivering adjustable output voltage from 1.23 V to 37 V with ±4% regulation over line and load, 52-kHz fixed-frequency operation, and integrated thermal shutdown and cycle-by-cycle current limiting - used in industrial power supplies and embedded motor drives.
For engineers reviewing the LM2576SX-ADJ/NOPB datasheet, LM2576SX-ADJ/NOPB pinout, LM2576SX-ADJ/NOPB application, or LM2576SX-ADJ/NOPB equivalent, key selection criteria include input voltage range (up to 40 V), feedback reference accuracy (1.23 V ±2.5%), ON/OFF control logic threshold (1.2 V low-enable), thermal resistance (RθJA = 42.6°C/W), and external component count (only four required).
Technical Context
The LM2576SX-ADJ/NOPB implements a fixed-frequency PWM buck topology with internal 52-kHz oscillator, bandgap-referenced error amplifier, and NPN power switch. It operates in continuous conduction mode under full load and transitions to discontinuous mode at light loads without instability.
Its functional block includes undervoltage lockout (not externally configurable), TTL-compatible ON/OFF pin (active-low enable), and internal current-limit protection triggered at 4.2–6.9 A peak switch current. Feedback is sensed at the ADJ pin with 100 nA bias current and 1.23 V nominal reference.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 3 A DC maximum - supports mid-power industrial loads without external current boosting. |
| Input Voltage Range | 4 V to 40 V - accommodates 12 V/24 V/36 V rails and transient surges up to 45 V absolute max. |
| Output Voltage Range | 1.23 V to 37 V (adjustable) - set via external resistor divider; 1.23 V reference enables precise low-voltage regulation. |
| Switching Frequency | 52 kHz ±10% - fixed internal oscillator simplifies EMI filtering and avoids external timing components. |
| Feedback Reference | 1.23 V ±2.5% - defines output as VOUT = 1.23 × (1 + R1/R2); tolerance directly impacts output accuracy. |
| Standby Current | 50 μA typical - enables low-power shutdown mode via ON/OFF pin without auxiliary circuitry. |
| Thermal Resistance | RθJA = 42.6°C/W (DDPAK) - requires ≥1 in² PCB copper area for safe 3-A operation at 70°C ambient. |
Pinout & Package
LM2576SX-ADJ/NOPB uses the KTT (DDPAK/TO-263-5) surface-mount package with exposed thermal pad connected internally to GND. Body size is 10.16 mm × 8.42 mm. The tab is electrically tied to GND and must be soldered to a large copper pour for thermal management.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VIN | Power input | Connects to high-side NPN collector; requires short, low-inductance path to input capacitor (≥100 μF). |
| 2 - OUTPUT | Switching node | Drives external inductor and catch diode cathode; high dv/dt node requiring careful layout. |
| 3 - GROUND | Power and signal return | Common reference for internal circuits and thermal pad; shortest possible trace to CIN ground. |
| 4 - FEEDBACK | Voltage sense input | High-impedance node (100 nA bias) monitoring resistor divider midpoint; sensitive to noise coupling. |
| 5 - ON/OFF | Enable control | Active-low TTL input; <1.2 V enables regulation, >1.4 V disables with 50 μA standby current. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated thermal shutdown | Activates at ~150°C junction temperature, halting switching until safe cooldown - prevents permanent damage during overload or poor heatsinking. |
| Cycle-by-cycle current limit | Triggers at 4.2–6.9 A peak switch current - protects MOSFET and inductor during short-circuit or startup inrush. |
| Fixed 52-kHz oscillator | Eliminates need for external timing components and reduces design iteration time for EMI-compliant layouts. |
| Low-component-count design | Requires only one inductor, one diode, two capacitors, and two resistors - accelerates prototyping and lowers BOM cost. |
| TTL-compatible ON/OFF control | Direct interface with microcontroller GPIO or logic-level signals - no level-shifting needed for enable/disable sequencing. |
Applications
| Industrial Motor Drive Power Supply | Embedded Network Equipment PSU |
|---|---|
Use Scenario: Provides regulated 5 V or 12 V rail for gate drivers and logic in 24 V-powered brushless DC motor controllers. IC Role / Device Role / Timing Role: Primary step-down regulator converting unregulated 24–36 V bus to stable low-voltage supply for control circuitry. Use Value: Delivers 3 A continuously with ±4% output accuracy and built-in current limiting - eliminates need for external OCP circuitry. | Use Scenario: Generates 3.3 V or 5 V from 12 V intermediate rail in merchant-class Ethernet switches and PoE injectors. IC Role / Device Role / Timing Role: Secondary DC-DC converter supplying power to PHYs, MACs, and management microcontrollers. Use Value: Fixed-frequency 52-kHz operation enables predictable EMI filtering; TO-263 package supports automated assembly and thermal reliability. |
| Test Equipment Auxiliary Supply | Appliance Mainboard Power |
Use Scenario: Powers analog front-end and digital logic in portable multimeters and benchtop power analyzers operating from 9–36 V battery or adapter inputs. IC Role / Device Role / Timing Role: Adjustable-output buck regulator enabling flexible voltage provisioning across multiple subsystems. Use Value: 1.23 V reference and wide output range (1.23–37 V) allow single design to support diverse sub-rail requirements. | Use Scenario: Supplies 5 V and 12 V rails for MCU, display, and solenoid drivers in smart washing machines and HVAC controllers. IC Role / Device Role / Timing Role: Primary offline-derived DC-DC stage replacing linear regulators to reduce heat and improve efficiency. Use Value: High efficiency (>77% at 3 A) and integrated protection eliminate external heatsinks - critical for sealed enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2576T-ADJ | TO-220-5 package (KC), higher RθJA = 32.4°C/W, same electrical specs. | Suitable for through-hole prototyping or lower-density boards where thermal mass of TO-220 suffices. | Select when manual assembly, vertical mounting, or legacy footprint compatibility is required. |
| LM2596SX-ADJ | 150-kHz switching frequency, 3 A rating, improved efficiency (~85% at 3 A), same pinout and package. | Better dynamic response and smaller passive components; not drop-in due to different frequency-dependent compensation. | Choose for new designs needing higher efficiency and reduced filter size - requires re-optimizing inductor/capacitor values. |
Compared with LM2576T-ADJ, the LM2576SX-ADJ/NOPB offers superior thermal performance on PCBs with adequate copper area; compared with LM2596SX-ADJ, it trades higher efficiency and smaller magnetics for proven 52-kHz EMI behavior and simpler loop compensation.
Availability
LM2576SX-ADJ/NOPB is available at Aetrix Electronics and suitable for industrial motor drives, embedded network equipment PSUs, test and measurement instruments, and appliance mainboard power systems requiring stable component supply and long-term manufacturability.
Supply support for LM2576SX-ADJ/NOPB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management ICs with broad industrial and automotive reach.
The LM2576 series was designed as a robust, low-component-count replacement for linear regulators in medium-power DC-DC conversion - targeting cost-sensitive, thermally constrained applications where simplicity and reliability outweigh ultra-high efficiency.
FAQ
What is the maximum input voltage rating for LM2576SX-ADJ/NOPB?
The LM2576SX-ADJ/NOPB has a recommended maximum input voltage of 40 V and an absolute maximum rating of 45 V. Exceeding 40 V continuously may reduce reliability or trigger internal protection. The HV variant (LM2576HV) supports up to 60 V, but LM2576SX-ADJ/NOPB is the standard-voltage version. Always observe derating guidelines per ambient temperature and thermal layout.
How do I set the output voltage of LM2576SX-ADJ/NOPB?
The output voltage of LM2576SX-ADJ/NOPB is set using a two-resistor feedback divider connected between VOUT, ADJ, and GND. With a 1.23 V internal reference, VOUT = 1.23 × (1 + R1/R2). For example, R1 = 1.21 kΩ and R2 = 1 kΩ yields ~2.66 V. R2 should be ≤10 kΩ to minimize noise sensitivity, and both resistors must be 1% tolerance for tight regulation.
Does LM2576SX-ADJ/NOPB require an external diode, and what type is recommended?
Yes, LM2576SX-ADJ/NOPB requires an external Schottky catch diode connected from OUTPUT to VOUT. TI recommends the 1N5822 (3 A, 40 V) or equivalent - fast recovery, low forward voltage (<0.55 V), and sufficient surge current rating. A diode with higher VF or slower recovery degrades efficiency and increases thermal stress on the LM2576SX-ADJ/NOPB.
What is the purpose of the ON/OFF pin on LM2576SX-ADJ/NOPB, and how is it used?
Pin 5 (ON/OFF) is an active-low enable input. Driving it below 1.2 V enables regulation; pulling it above 1.4 V places LM2576SX-ADJ/NOPB in standby mode with 50 μA quiescent current. It can be controlled directly by a microcontroller GPIO or open-collector logic. Never leave this pin floating - tie to GND via 10 kΩ resistor if always enabled.
Can LM2576SX-ADJ/NOPB be used in synchronous rectification configurations?
No, LM2576SX-ADJ/NOPB is a non-synchronous buck regulator with an internal NPN transistor and requires an external catch diode. It does not support synchronous rectification - no gate drive outputs or timing signals are provided for an external low-side MOSFET. For synchronous operation, consider the LMR51430 or LM76003 families instead.
LM2576SX-ADJ/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.23V
- Voltage - Output (Max):
- 37V
- Current - Output:
- 3A
- Frequency - Switching:
- 52kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TO-263 (DDPAK-5)
LM2576SX-ADJ/NOPB FAQ
1.How can I place an order for LM2576SX-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2576SX-ADJ/NOPB on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LM2576SX-ADJ/NOPB reliable?
The price and inventory of LM2576SX-ADJ/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2576SX-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM2576SX-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2576SX-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2576SX-ADJ/NOPB?
LM2576SX-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2576SX-ADJ/NOPB order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LM2576SX-ADJ/NOPB?
For technical support, including LM2576SX-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2576SX-ADJ/NOPB requirements.
6.How does Aetrix verify that LM2576SX-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2576SX-ADJ/NOPB products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM2576SX-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM2576SX-ADJ/NOPB?
All LM2576SX-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2576SX-ADJ/NOPB, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LM2576SX-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM2576SX-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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