LM2596SX-5.0/NOPB is a classic step-down DC-DC voltage regulator IC from TI (formerly National Semiconductor), with fixed 5V output and up to 3A output current. The device uses pulse-width modulation (PWM) buck architecture with a fixed switching frequency of 150kHz, supporting a wide 4.5V~40V input voltage range for converting various higher voltages to stable 5V power supplies.

The device integrates a power switch transistor (NMOS), requiring only a minimal number of external components to form a complete buck power supply. A typical minimum system requires only input/output filter capacitors, a freewheeling diode, an inductor, and a feedback resistor network (omitted for fixed-output versions).

Built-in protection features include: cycle-by-cycle current limiting, thermal shutdown, undervoltage lockout (UVLO), and output short-circuit protection. The TO-263-5 package with exposed tab supports 3A continuous output, and with a heatsink can achieve higher power output. The device operates over a wide temperature range and is widely used in industrial control, communication equipment, consumer electronics, and automotive electronics for step-down power supply designs.

Note: For detailed electrical parameters, refer to the official TI LM2596 datasheet. Specifications are subject to change without notice. Design engineers should verify all parameters before final design.

LM2596SX-5.0/NOPB uses the TO-263-5 (D2PAK, 5-pin) package, a classic surface-mount power package with an exposed bottom thermal tab. The D2PAK package offers excellent thermal performance; the large bottom thermal tab requires good solder connection to the PCB copper plane for effective heat dissipation.

The TO-263-5 package pin arrangement is suitable for standard SMT assembly. The 5th pin (Tab) is the thermal tab connected to chip ground and serves as the primary heat dissipation path. In high-current applications, it is recommended to lay a large copper area on the PCB back side and connect via thermal vias to enhance heat dissipation.

LM2596SX-5.0/NOPB TO-263-5 functional pin definitions:

• Pin 1 - VIN (Input Voltage): Power input pin, 4.5V~40V; a filter capacitor (minimum 22uF electrolytic + 0.1uF ceramic) is recommended near the pin.
• Pin 2 - OUTPUT: Internal power switch output, connected to the inductor and freewheeling diode. Traces should be short and wide to minimize EMI.
• Pin 3 - GND: Chip ground pin; should be directly connected to input/output capacitor grounds and the PCB ground plane.
• Pin 4 - FEEDBACK: In the fixed 5V version, this pin is internally connected to the output voltage feedback network and requires no external connection.
• Pin 5 - ON/OFF: Chip enable control pin; high (>1.3V) enables normal operation, low (<0.7V) shuts down output. Can be left open (internal default pull-up).

The following alternative parts are listed for reference. Before selecting an alternative, verify communication interface, supply voltage, security algorithm compatibility, and software API differences.

Texas Instruments (NASDAQ: TXN), headquartered in Dallas, Texas, USA, is one of the world's largest analog semiconductor companies. TI (formerly National Semiconductor)'s LM2596 series is one of the most classic and widely used buck regulators in the industry, with over 20 years of production and application experience, and a stable and reliable supply chain.

TI has multiple technical support centers and local warehouses in China, enabling fast response to domestic customer needs for samples and volume production.