LM2596S-5.0/NOPB vs LM2596T-3.3: Component Comparison for Power Electronics Engineers
Quick verdict
For standard 5 V, 3 A buck regulator designs targeting surface-mount assembly, the LM2596S-5.0/NOPB is the clear choice due to its fixed 5 V output and compact TO-263-6 package. For applications requiring 3.3 V output with through-hole mounting and potentially easier prototyping or retrofit, the LM2596T-3.3 is preferable, despite its larger TO-220-5 package.
Spec comparison table
| Spec | LM2596S-5.0/NOPB | LM2596T-3.3 | Notes |
|---|---|---|---|
| Function | Step-Down | Step-Down | Equivalent function; no advantage. |
| Input Voltage Max (V) | 40 | 40 | Equivalent max input voltage rating. |
| Input Voltage Min (V) | 4.5 | Not specified | LM2596S-5.0/NOPB advantage: defined 4.5 V min input allows tighter input voltage design. |
| Mounting Type | Surface Mount | Through Hole | Depends on assembly process; surface mount (LM2596S) saves board space, but through-hole (LM2596T) eases prototyping and heatsinking. |
| Number of Outputs | 1 | 1 | Equivalent. |
| Operating Temperature Range (TJ) | -40°C ~ 125°C | -40°C ~ 125°C | Equivalent thermal operating range. |
| Output Configuration | Positive | Positive | Equivalent. |
| Output Current Max (A) | 3 | 3 | Equivalent max load current. |
| Output Type | Fixed | Fixed | Equivalent fixed output voltage types. |
| Output Voltage Min (V) | 5 | 3.3 | Fixed output voltage difference; 5 V vs 3.3 V. Choose based on system voltage needs. |
| Package Case | TO-263-6, D2PAK (5 Leads + Tab) | TO-220-5 | TO-263-6 is surface mount, smaller footprint; TO-220-5 is through-hole with larger thermal mass. |
| Supplier Device Package | TO-263 (DDPAK-5) | TO-220-5L | Reflects mounting style and mechanical robustness differences. |
| Switching Frequency Typ (kHz) | 150 | 150 | Identical switching frequency simplifies EMI and inductor selection. |
| Synchronous Rectifier | No | No | Both use diode rectifiers; expect similar efficiency profiles. |
| Topology | Buck | Buck | Equivalent topology. |
Design trade-offs
The LM2596S-5.0/NOPB’s surface-mount TO-263-6 package is significantly more compact than the LM2596T-3.3’s through-hole TO-220-5. This affects PCB real estate and thermal management strategies. The TO-220 package generally offers better thermal dissipation through a larger exposed metal tab and easier attachment of heatsinks, which can simplify thermal design in high power applications or borderline thermal environments. Conversely, the TO-263-6 package requires more careful PCB copper area design and thermal vias for effective heat spreading.
Both devices share the same switching frequency of 150 kHz, which makes inductor and capacitor selection straightforward and consistent across designs. However, the fixed output voltage difference—5 V vs. 3.3 V—will influence downstream power rail design. The LM2596S-5.0/NOPB’s 5 V output is suitable for legacy 5 V logic and peripherals, whereas the LM2596T-3.3 targets modern low-voltage digital ICs requiring 3.3 V rails.
Neither device supports synchronous rectification, meaning both rely on external Schottky diodes for the freewheeling path. This must be factored into efficiency and thermal calculations, especially at high load currents. Efficiency curves for these devices generally show similar profiles given the identical topology and switching frequency, but the output voltage level affects conduction losses in the diode and MOSFET. For example, the 3.3 V output version may have slightly higher conduction losses due to higher duty cycle at identical input voltages.
The LM2596S-5.0/NOPB specifies a minimum input voltage of 4.5 V, providing a clear boundary for input supply design, whereas the LM2596T-3.3’s minimum input voltage is not provided, which requires the engineer to verify from original datasheets or test empirically. This can be critical when designing systems with limited input voltage headroom.
From a cost perspective, through-hole parts like the LM2596T-3.3 are often cheaper in prototype quantities and easier to hand-solder, but surface-mount devices like the LM2596S-5.0/NOPB benefit from automated pick-and-place assembly and are preferred in volume production due to size and weight savings.
Use-case fit
Choose LM2596S-5.0/NOPB when…
- Designing a 5 V, 3 A power rail for compact, automated surface-mount PCB assemblies.
- Working within a constrained PCB footprint where TO-263-6’s smaller size reduces board area and cost.
- The input supply voltage ranges from 4.5 V up to 40 V, with known minimum voltage requirements.
- Thermal management is handled by PCB copper pours and heat-spreading vias rather than large heatsinks.
- The application involves modern manufacturing lines prioritizing surface-mount technology.
Choose LM2596T-3.3 when…
- A 3.3 V, 3 A fixed output voltage is required, compatible with modern low-voltage digital ICs.
- Prototyping or low-volume production where through-hole components simplify manual assembly and testing.
- The design benefits from easy attachment of external heatsinks due to TO-220 package.
- The input voltage range is wide but minimum input voltage is not critical or can be verified by testing.
- The board size is less constrained, and mechanical robustness of the larger package is preferred.
Drop-in compatibility
The LM2596S-5.0/NOPB and LM2596T-3.3 are not pin-compatible or footprint-compatible due to different package types (TO-263-6 vs. TO-220-5). The LM2596S-5.0/NOPB uses a surface-mount D2PAK-style footprint with 5 leads plus a thermal tab, while the LM2596T-3.3 uses a through-hole 5-pin TO-220 package. Substituting one for the other requires mechanical and PCB layout changes, including mounting style, thermal management, and possible re-routing of pins. Also, the fixed output voltage differs, so output filtering and downstream design must be adjusted accordingly.
Alternatives to consider
- LM2596-ADJ (Texas Instruments): Adjustable output voltage version of LM2596, offering design flexibility for custom output voltages.
- MP1584EN (Monolithic Power Systems): Smaller, synchronous buck converter with higher switching frequency and integrated MOSFETs for improved efficiency in compact layouts.
- LT1763 (Analog Devices/Linear Technology): Low noise linear regulator for low current, low dropout applications where switching noise is a concern.