LM2596T-ADJ/NOPB vs. LM2596T-ADJ: A Practical Comparison
Quick verdict: For high-volume production runs where component cost is paramount, the LM2596T-ADJ/NOPB is the clear winner due to its lower unit cost. However, if you need guaranteed performance and a slightly tighter tolerance on key parameters, the LM2596T-ADJ is the safer choice, especially in designs requiring precise output voltage regulation.
Spec Comparison Table
| Spec | LM2596T-ADJ/NOPB | LM2596T-ADJ | Notes |
|---|---|---|---|
| Function | Step-Down | Step-Down | Identical. |
| Output Configuration | Positive | Positive | Identical. |
| Topology | Buck | Buck | Identical. |
| Output Type | Adjustable | Adjustable | Identical. |
| Number of Outputs | 1 | 1 | Identical. |
| Input Voltage Min | 4.5V | 4.5V | Identical. |
| Input Voltage Max | 40V | 40V | Identical. |
| Output Voltage Min | 1.2V | 1.2V | Identical. |
| Output Voltage Max | 37V | 37V | Identical. |
| Output Current Max | 3A | 3A | Identical. |
| Switching Frequency Typ | 150kHz | 150kHz | Identical. |
| Synchronous Rectifier | No | No | Identical. |
| Operating Temperature Range (TJ) | -40°C ~ 125°C | -40°C ~ 125°C | Identical. |
| Mounting Type | Through Hole | Through Hole | Identical. |
| Package Case | TO-220-5 Formed Leads | TO-220-5 Formed Leads | Identical. |
| Supplier Device Package | TO-220-5 | TO-220-5 | Identical. |
| Reel Diameter | N/A | N/A | Both are available in tape and reel packaging, but the specific reel diameter isn’s specified. |
| Cavity A0 Dimension | N/A | N/A | Both are available in tape and reel packaging, but the specific A0 dimension isn’t specified. |
| Cavity B0 Dimension | N/A | N/A | Both are available in tape and reel packaging, but the specific B0 dimension isn’t specified. |
| Cavity K0 Dimension | N/A | N/A | Both are available in tape and reel packaging, but the specific K0 dimension isn’t specified. |
| Reel Width Typ | N/A | N/A | Both are available in tape and reel packaging, but the specific reel width isn’t specified. |
| Pitch Typ | N/A | N/A | Both are available in tape and reel packaging, but the specific pitch isn’t specified. |
| Reel Width Min | N/A | N/A | Both are available in tape and reel packaging, but the specific reel width min isn’t specified. |
| Device Package Type | DDPAK/ KTT | DDPAK/ KTT | Identical. |
| Pins | 5 | 5 | Identical. |
| Quantity Per Reel | 500 | 500 | Identical. |
| Package Diameter Typ | 330.0 mm | 330.0 mm | Identical. |
| Package Width Typ | 24.4 mm | 24.4 mm | Identical. |
| Package Length Typ | 10.75 mm | 10.75 mm | Identical. |
| Package Width Min | 14.85 mm | 14.85 mm | Identical. |
| Package Length Max | 5.0 mm | 5.0 mm | Identical. |
| Quadrant Assignment | Q2 | Q2 | Identical. |
| Tube Length | N/A | N/A | Both are available in tube packaging, but the specific tube length isn’t specified. |
| Tube Width | N/A | N/A | Both are available in tube packaging, but the specific tube width isn’t specified. |
| Tube Height | N/A | N/A | Both are available in tube packaging, but the specific tube height isn’t specified. |
| Alignment Groove Width | N/A | N/A | Both are available in tube packaging, but the specific alignment groove width isn’t specified. |
| Tube Length Min | N/A | N/A | Both are available in tube packaging, but the specific tube length min isn’t specified. |
| Tube Width Typ | N/A | N/A | Both are available in tube packaging, but the specific tube width typ isn’t specified. |
| Alignment Groove Width Max | N/A | N/A | Both are available in tube packaging, but the specific alignment groove width max isn’t specified. |
| Tube Height Min | N/A | N/A | Both are available in tube packaging, but the specific tube height min isn’t specified. |
Design Trade-offs
The core difference between the LM2596T-ADJ/NOPB and LM2596T-ADJ lies in the manufacturing process and quality control. The /NOPB suffix indicates a production part with less stringent testing and sorting. This translates to a lower cost, which is the primary reason to select it. However, this also means you might experience slightly higher parameter drift over temperature and time, and a slightly higher chance of encountering a part outside of the datasheet specifications.
From a layout perspective, both parts are essentially identical. The TO-220 package is notoriously sensitive to ground plane integrity. Ensure a low-impedance path from the source ground to the device ground and the load ground. Thermal performance is also a key consideration. The TO-220 package is adequate for moderate power levels, but for higher power applications (closer to the 3A limit), consider using a heatsink. The /NOPB variant’s potentially looser tolerances might exacerbate thermal issues if the feedback loop isn’t well-tuned.
Gate drive requirements are identical, as the internal circuitry is the same. However, the potential for slightly higher internal resistance in the /NOPB part could lead to marginally higher switching losses. This is unlikely to be significant unless you are operating at very high frequencies or with very fast switching times.
Use-case Fit
Choose LM2596T-ADJ/NOPB when…
- You’re designing a high-volume consumer product where component cost is a critical factor (e.g., battery-powered toys, low-cost power adapters).
- The application has a wide operating voltage range and doesn’t require extremely precise output voltage regulation (e.g., charging a battery where a small voltage variation is acceptable).
- You have a robust feedback loop design that can tolerate slight variations in component parameters.
- You are comfortable with a slightly higher risk of encountering a part outside of the datasheet specifications.
- You are designing a simple power supply for a non-critical application.
Choose LM2596T-ADJ when…
- You’re designing a power supply for a sensitive electronic device that requires precise output voltage regulation (e.g., powering a microcontroller or a sensor).
- You need guaranteed performance and a lower risk of encountering a part outside of the datasheet specifications.
- You’re designing a power supply for a medical device or other safety-critical application.
- You are implementing a tightly regulated voltage rail.
- You are prototyping or developing a new design and want to minimize the risk of unexpected behavior.
Drop-in Compatibility
Pin-compatibility is excellent. The TO-220 footprint is identical. Functionally, they are drop-in replacements. However, be aware of the potential for slightly different performance characteristics due to the less stringent testing of the /NOPB variant. In a production environment, it’s advisable to perform some limited testing on a sample of /NOPB parts to ensure they meet your application’s requirements.
Alternatives to Consider
- LM2596-ADJ: A slightly older version without the
/NOPBsuffix, offering similar performance to the LM2596T-ADJ but potentially with a slightly higher cost. - TPS54061: A synchronous buck regulator offering higher efficiency and smaller size, but with a more complex design.
- MP1584EN: A compact and cost-effective alternative with integrated synchronous rectification, suitable for space-constrained applications.