LM2596S-ADJ/NOPB vs LM2596T-5.0: Component Comparison for Hardware Engineers
Quick verdict
For designs requiring a flexible output voltage across a broad range, the LM2596S-ADJ/NOPB wins due to its adjustable output from 1.2V up to 37V, making it ideal for custom voltage rails. Conversely, if your design needs a fixed 5V output with straightforward implementation and easier thermal management, the LM2596T-5.0 is the better choice due to its fixed 5V output and through-hole package simplifying heatsinking.
Spec comparison table
| Spec | LM2596S-ADJ/NOPB | LM2596T-5.0 | Notes |
|---|---|---|---|
| Function | Step-Down Buck | Step-Down Buck | Same function; no difference. |
| Input Voltage Max (V) | 40V | 40V | Identical max input voltage capabilities. |
| Input Voltage Min (V) | 4.5V | 4.5V | Identical min input voltage capabilities. |
| Mounting Type | Surface Mount (TO-263-6/D2PAK) | Through Hole (TO-220-5) | LM2596T-5.0’s through-hole is easier for manual assembly and heatsinking; LM2596S-ADJ better for automated SMT. |
| Number of Outputs | 1 | 1 | No difference. |
| Operating Temperature (TJ) | -40°C to 125°C | -40°C to 125°C | Same operating temperature range. |
| Output Configuration | Positive | Positive | No difference. |
| Max Output Current (A) | 3A | 3A | Same max current rating. |
| Output Type | Adjustable | Fixed 5V | LM2596S-ADJ provides voltage flexibility; LM2596T-5.0 is fixed voltage for simpler design. |
| Output Voltage Max (V) | 37V | Not specified (fixed 5V) | Adjustable part covers wider voltage range, important for custom rails. |
| Output Voltage Min (V) | 1.2V | 5V | Adjustable part supports lower voltages down to 1.2V. |
| Package Case | TO-263-6, D2PAK (5 Leads + Tab) | TO-220-5 Formed Leads | TO-220-5 package (LM2596T-5.0) offers better thermal dissipation and simpler heatsinking. |
| Supplier Device Package | TO-263 (DDPAK-5) | TO-220-5 | See above. |
| Switching Frequency (Typ) | 150kHz | 150kHz | Same switching frequency simplifies inductor and capacitor selection. |
| Synchronous Rectifier | No | No | Both require external Schottky diode, impacting efficiency and layout. |
| Topology | Buck | Buck | No difference. |
Design trade-offs
The foremost difference between these two devices is output voltage flexibility versus fixed voltage. The LM2596S-ADJ/NOPB’s adjustable output (1.2V to 37V) provides design versatility, allowing a single regulator to serve multiple rails or adapt to varying load requirements. This flexibility comes at the cost of additional external components—specifically, the feedback resistor divider—and potentially more board space and layout complexity.
The LM2596T-5.0’s fixed 5V output simplifies BOM and layout since the feedback network is integrated internally. This reduces design iteration time and risk of misconfiguration but limits voltage options to 5V only, which is common but not universal.
Package type impacts thermal management and assembly. The LM2596T-5.0’s TO-220-5 through-hole package offers superior thermal conduction via a larger metal tab and formed leads, making it easier to mount to heatsinks and manage thermal dissipation at or near the 3A maximum current. This is particularly advantageous in prototypes or low-volume production where manual assembly is common.
In contrast, the LM2596S-ADJ/NOPB’s TO-263 surface-mount package is smaller and better suited for automated assembly and space-constrained PCBs. However, TO-263’s thermal dissipation relies heavily on PCB copper area and thermal vias, requiring careful layout to maintain junction temperature within limits, especially at high currents.
Both devices lack synchronous rectification, meaning efficiency is limited by the external Schottky diode’s forward drop and switching losses. This is typical for this class but should be accounted for in thermal design and efficiency budgeting.
Switching frequency is identical at 150kHz, meaning inductor and capacitor choices can be similar across both devices. However, the adjustable device’s feedback loop may require more careful compensation if the output voltage is changed widely, affecting transient response and stability.
Cost-wise, through-hole packages like the LM2596T-5.0 often have slightly lower unit cost but higher assembly cost in volume SMT lines. The LM2596S-ADJ/NOPB, being SMT, integrates better into automated production, which can offset raw component cost differences.
Use-case fit
Choose LM2596S-ADJ/NOPB when:
- You need a custom or multiple output voltages in the 1.2V to 37V range for powering various rails in a single design.
- Board space is limited and surface-mount assembly is preferred or required.
- Your design includes automated SMT assembly processes where TO-263 packages are standard.
- You require fine voltage tuning for sensitive analog or RF circuits where output voltage adjustment improves performance.
- You want to prototype with a single regulator variant that can be adjusted via external resistors rather than stocking multiple fixed-voltage parts.
Choose LM2596T-5.0 when:
- Your application requires a stable, fixed 5V output rail, such as powering logic or microcontrollers.
- You prefer through-hole components for easier manual soldering, rework, or prototyping.
- Thermal management is critical, and you need to attach a large heatsink or fan directly to the package tab.
- Your production volume is low or medium, and manual assembly or hand testing is expected.
- You want a plug-and-play regulator with minimal external components and no need for resistor dividers.
Drop-in compatibility
These two devices are not pin-compatible. The LM2596S-ADJ/NOPB uses a TO-263-6 (D2PAK-5) surface-mount package with 5 leads plus a tab, while the LM2596T-5.0 uses a physically larger TO-220-5 through-hole package with formed leads. Their pinouts and mechanical footprints differ, so substituting one for the other requires PCB redesign. Thermal considerations and mounting methods also differ significantly between the two, so they should not be swapped without comprehensive evaluation.
Alternatives to consider
- LM2675 Series (Texas Instruments): Offers similar 3A buck regulation with fixed and adjustable options, but with a lower switching frequency (~52kHz) and smaller package options for space-constrained designs.
- MP1584EN (Monolithic Power Systems): A compact, 3A buck regulator with synchronous rectification for improved efficiency in the same current range.
- TPS5430 (Texas Instruments): A 3A, 500kHz switching regulator with integrated synchronous rectifier, providing higher efficiency and smaller inductors but requiring more careful layout.
This comparison should help engineers select the appropriate LM2596 variant based on voltage flexibility, assembly type, and thermal requirements.