LM2596S-ADJ/NOPB vs LM2596T-ADJ: A Component Comparison for Power Electronics Engineers
Quick verdict
For space-constrained designs requiring surface-mount assembly and moderate thermal dissipation, the LM2596S-ADJ/NOPB is the better choice due to its TO-263 (D2PAK-5) package and standard operating range. For applications where through-hole mounting, easier manual assembly, or improved heat sinking via a TO-220-5 package is prioritized, the LM2596T-ADJ is preferable. Both support identical electrical specifications, so package type and thermal management are the key differentiators.
Spec comparison table
| Spec | LM2596S-ADJ/NOPB | LM2596T-ADJ | Notes |
|---|---|---|---|
| Function | Step-Down | Step-Down | Identical function |
| Input voltage max | 40 V | 40 V | Identical |
| Input voltage min | 4.5 V | 4.5 V | Identical |
| Mounting type | Surface Mount | Through Hole | Surface mount (LM2596S) better for automated assembly and high-density PCBs; through-hole (LM2596T) facilitates prototyping and manual soldering |
| Number of outputs | 1 | 1 | Identical |
| Operating temperature range | -40°C to 125°C (TJ) | -40°C to 125°C (TJ) | Identical |
| Output configuration | Positive | Positive | Identical |
| Output current max | 3 A | 3 A | Identical |
| Output type | Adjustable | Adjustable | Identical |
| Output voltage max | 37 V | 37 V | Identical |
| Output voltage min | 1.2 V | 1.2 V | Identical |
| Package case | TO-263-6, D2PAK (5 Leads + Tab), TO-263BA | TO-220-5 Formed Leads | TO-220-5 (LM2596T) generally easier to cool with a heat sink; TO-263 (LM2596S) better for compact SMD layouts |
| Supplier device package | TO-263 (DDPAK-5) | TO-220-5 | See above |
| Switching frequency typ | 150 kHz | 150 kHz | Identical |
| Synchronous rectifier | No | No | Identical |
| Topology | Buck | Buck | Identical |
| Alignment groove width | N/A | B (max 4.2 mm) | Only relevant for mechanical assembly; no direct electrical impact |
| Package diameter typ | N/A | 330.0 mm | Likely a documentation artifact; physical package diameter is not 330 mm |
| Package length max | N/A | 5.0 mm | Physical dimension; LM2596T is taller vertically but smaller lengthwise |
| Package length typ | N/A | 10.75 mm | See above |
| Package width min | N/A | 14.85 mm | See above |
| Package width typ | N/A | 24.4 mm | See above |
| Pins | 6 (5 leads + tab) | 5 | LM2596S has a thermal tab lead, potentially better thermal conduction; LM2596T has 5 pins only |
| Pitch typ | N/A | Not specified | Minor mechanical consideration |
| Quantity per reel | N/A | 500 | Relevant for automated assembly; LM2596S may be tape and reel, LM2596T typically tube |
| Tube height min | N/A | 10.74 µm | Mechanical packaging detail; negligible impact on electrical design |
| Tube length min | N/A | 502 mm | Mechanical packaging detail |
| Tube width typ | N/A | 25 mm | Mechanical packaging detail |
Design trade-offs
The primary distinction between the LM2596S-ADJ/NOPB and LM2596T-ADJ lies in package style and mounting approach. The LM2596S-ADJ/NOPB uses a TO-263 (D2PAK-5) surface-mount package, which is suited for automated pick-and-place assembly and compact PCB designs. Its thermal tab and 6-lead configuration aid in heat dissipation but require attention to PCB copper area as the tab is typically soldered to a large pad for thermal conduction. The surface-mount nature reduces parasitic inductances in high-frequency switching but demands careful PCB layout to avoid EMI and ensure thermal performance.
The LM2596T-ADJ’s TO-220-5 package is through-hole with formed leads, which simplifies manual soldering and prototyping. The larger physical size and exposed metal tab facilitate attaching a heat sink, enabling better thermal management in high-power or thermally constrained environments. However, through-hole mounting limits PCB routing density and automated assembly efficiency. The formed leads may introduce slightly higher parasitic inductances compared to the surface-mount leads, which could marginally affect EMI and transient response.
Both devices share nearly identical electrical specifications, including a 3 A maximum output current, 150 kHz switching frequency, and input voltage range of 4.5 V to 40 V. There is no synchronous rectification, so external Schottky diodes and proper diode selection remain critical for efficiency and thermal considerations.
From a cost perspective, TO-220 parts like the LM2596T-ADJ often have slightly higher per-unit cost due to larger package size and mechanical complexity, but this is offset by lower assembly costs in low-volume or manual assembly scenarios. The LM2596S-ADJ/NOPB tends to be favored in volume manufacturing where surface mount assembly drives down labor costs and assembly time.
In terms of thermal performance, the LM2596T-ADJ’s larger metal tab and heat sink compatibility make it more forgiving in designs with poor PCB thermal conductivity or higher ambient temperatures. The LM2596S-ADJ/NOPB demands more robust PCB thermal design—large copper pours, thermal vias, and possibly forced airflow—to maintain junction temperatures inside the -40°C to 125°C range under full load.
Use-case fit
Choose LM2596S-ADJ/NOPB when…
- Designing compact, automated assembly-friendly power supplies where PCB real estate is limited.
- Implementing high-density power conversion on multilayer PCBs with controlled impedance and thermal vias.
- Operating in environments where forced cooling or large PCB copper areas are feasible for heat dissipation.
- Optimizing for lower assembly costs at volume with surface-mount technology (SMT) lines.
- Integrating with modern, low-profile enclosures where component height must be minimized.
Choose LM2596T-ADJ when…
- Prototyping or low-volume builds requiring manual soldering and easy replacement.
- Applications demanding robust heat sinking options via clip-on or bolt-on heat sinks.
- Designs where through-hole mounting is preferred or required for mechanical strength.
- Environments with poor PCB thermal conductivity or elevated ambient temperatures.
- Circuits where slightly relaxed EMI constraints and layout flexibility due to larger package size are acceptable.
Drop-in compatibility
The LM2596S-ADJ/NOPB and LM2596T-ADJ are not footprint compatible due to different package types (TO-263-6 vs TO-220-5) and pin counts (6 leads including thermal tab vs 5 leads). They are not pin compatible without PCB modifications. The LM2596S has an additional thermal tab lead that must be soldered to a PCB copper area, whereas the LM2596T uses the metal tab as its heat sink mounting point with 5 pins.
Substituting one for the other requires a PCB redesign or an adapter board. The electrical functions and pin assignments are similar, but mechanical and thermal mounting considerations differ significantly. No direct drop-in replacement is possible.
Alternatives to consider
- TPS5430 (TI): A synchronous buck regulator with integrated MOSFETs offering higher efficiency at similar current ratings, suitable for designs where efficiency and thermal performance are critical.
- MC34063 (ON Semiconductor): A low-cost, versatile switching regulator for lower power applications, though limited to lower currents and switching frequencies.
- LT1763 (Analog Devices): A low-noise, low-dropout regulator, not a switching regulator but an alternative for low-noise linear regulation when efficiency is less critical.