Part of the Day · LM2596 — TO-263-5 3A step-down switching regulator

Part of the Day · 2026-10-23

A 150kHz step-down (buck) switching regulator that efficiently lowers a higher voltage at up to 3A. It comes in fixed 3.3V, 5V and 12V versions and an adjustable (ADJ) version, and is used on many off-the-shelf DC-DC step-down modules.

3D view

3D drawing based on the dimensions of the TI datasheet TO-263 (KTT0005B) drawing (lead bend shape is approximate). The grey plate at the back is the heatsink tab soldered to the PCB. Not to scale.

Actual size · top view

↓ Actual size, left edge aligned to 0 on the ruler

One ruler tick = 1mm. On PC this is actual size on a 24-inch FHD monitor at 100% zoom; on iPhone it adjusts automatically. For other screens, use “Calibrate ruler” below.

Enlarged (TO-263-5 · top view · approx. 7×)

Pins 1 Input · 2 Output (switch) · 3 GND · 4 Feedback · 5 ON/OFF

Package TO-263-5

Actual size · Right side view

Height 4.57mm · overall length max 14.35mm · lead pitch 1.7mm (TI KTT0005B drawing)

Enlarged · Right side view · approx. 7×

Right side view — the five leads overlap and look like one. The leads bend like gull wings down to the PCB (bend shape approximate); the grey part on the left is the heatsink.

Key specifications

Values are from the Texas Instruments datasheet.

Marking and pins

Typical uses

• Supply stepping 12 ~ 24V down to 5V/3.3V — less heat than a linear regulator
• DC-DC step-down modules, adjustable supplies built with the adjustable version

Companion & similar parts

• LM2596-ADJ — Adjustable version — 1.23V feedback, output set by two resistors
• LM2596-5.0 — Fixed 5V version — 4.8 ~ 5.2V from 7 ~ 40V input
• 1N5825 — 5A 40V Schottky catch diode used in the datasheet example circuit

Place the input capacitor and catch diode close to the IC with short traces. Pin 2 (output) is the switching node, so keep its copper area small. If the pin 5 ON/OFF input is unused, tie it to GND or leave it open and the regulator stays on.