Comparison: LM2596S-5.0/NOPB vs LM2596T-3.3/LF03
Quick verdict
For designs requiring a fixed 5 V output with surface-mount assembly, the LM2596S-5.0/NOPB offers a more compact solution with a D2PAK package and standard 150 kHz switching, suitable for moderate thermal dissipation on PCBs. For through-hole applications needing a fixed 3.3 V output and robust thermal handling, the LM2596T-3.3/LF03 in TO-220-5 package is preferable, especially when easier heat sinking and manual assembly are priorities.
Spec comparison table
| Spec | LM2596S-5.0/NOPB | LM2596T-3.3/LF03 | Notes |
|---|---|---|---|
| Function | Step-Down Buck Regulator | Step-Down Buck Regulator | Equivalent function. |
| Input Voltage Min | 4.5 V | 4.5 V | Equal. |
| Input Voltage Max | 40 V | 40 V | Equal. |
| Output Voltage Fixed | 5 V | 3.3 V | Different fixed outputs; select per target rail voltage. |
| Output Current Max | 3 A | 3 A | Equal max current rating. |
| Output Configuration | Positive | Positive | Equal. |
| Number of Outputs | 1 | 1 | Equal. |
| Topology | Buck | Buck | Equal. |
| Switching Frequency Typical | 150 kHz | 150 kHz | Equal typical frequency; note LM2596T-3.3 datasheet indicates wide frequency range 110 kHz–2.2 MHz, but typical 150 kHz. LM2596S only states 150 kHz typical. |
| Synchronous Rectifier | No | No | Equal. |
| Operating Temperature Range (TJ) | -40°C to 125°C | -40°C to 125°C | Equal. |
| Mounting Type | Surface Mount | Through Hole | Surface mount (LM2596S) enables smaller PCB footprint; TO-220 (LM2596T) easier thermal management and prototyping. |
| Package Case | TO-263-6, D2PAK (5 Leads + Tab) | TO-220-5 Formed Leads | TO-263 is lower profile, better for automated SMT; TO-220 better for heat sinking and manual handling. |
| Supplier Device Package | TO-263 (DDPAK-5) | TO-220-5 | Matches above packaging notes. |
| Operating Quiescent Current Typical | Not explicitly stated | 5 mA | LM2596T-3.3 specified at ~5 mA; LM2596S data not given explicitly. |
| Standby Current Typical | Not explicitly stated | 80 μA | LM2596T-3.3 datasheet provides standby current; LM2596S does not specify. |
| Shutdown Quiescent Current Max | Not specified | 200 μA | Only LM2596T-3.3 provides shutdown current info. |
| Output Voltage Tolerance | Not specified | ±4% | Only LM2596T-3.3 specifies tolerance; expect similar for LM2596S. |
| Maximum Junction Temperature | Not explicitly stated (typ. 125°C TJ) | 150°C | LM2596T-3.3 datasheet lists 150°C max TJ; LM2596S datasheet states 125°C TJ. |
| Thermal Resistance, Junction-to-Ambient (typical) | 50 °C/W (5 pins to TO-263) | Not explicitly stated | LM2596S thermal resistance typical is 50 °C/W; LM2596T-3.3 data not directly provided but TO-220 generally better heat sinking. |
| Thermal Resistance, Junction-to-Case (typical) | 2 °C/W | 2 °C/W | Equal typical RθJC. |
| Input Voltage Range (line & load) | 4.5 V to 40 V | 1.2 V to 37 V ±4% | LM2596T-3.3 supports wider input range (down to 1.2 V typical) vs 4.5 V minimum for LM2596S. Useful for low voltage inputs. |
| Output Voltage Ripple Typical | Not explicitly stated | 62 mV p-p | LM2596T-3.3 ripple voltage specified; LM2596S ripple not explicitly specified. |
| Efficiency Minimum | Not specified | 73% | LM2596T-3.3 specifies minimum efficiency; LM2596S does not specify efficiency explicitly. |
| Inductance Typical | Not specified | 33 μH | LM2596T-3.3 typical inductance provided; LM2596S datasheet does not specify recommended inductance explicitly. |
| Output Capacitor ESR | Not specified | 0.1 Ω (typ) | LM2596T-3.3 specifies low ESR capacitors for output filtering; LM2596S does not specify. |
| Input Capacitor Size Typical | Not specified | 68 μF, 25 V (tantalum) | LM2596T-3.3 recommends specific input capacitor sizing; LM2596S does not specify. |
| Output Capacitor Size Typical | Not specified | 330 μF to 820 μF electrolytic | LM2596T-3.3 specifies output capacitor range; LM2596S datasheet does not. |
| Diode Type Recommended | Not specified | Schottky diode | LM2596T-3.3 recommends Schottky for switching diode; LM2596S datasheet does not specify. |
Design trade-offs
The first major difference is packaging and mounting type. The LM2596S-5.0/NOPB comes in a TO-263-6 (D2PAK) surface-mount package, which is lower profile and better suited for automated PCB assembly and compact designs. However, the TO-263 package has a higher junction-to-ambient thermal resistance (~50 °C/W typical) compared to the TO-220 package, meaning heat dissipation relies heavily on PCB copper area and thermal vias. Designers must allocate sufficient copper area and possibly a heat sink pad to keep junction temperature within limits at 3 A output.
In contrast, the LM2596T-3.3/LF03 uses a TO-220-5 through-hole package with formed leads, which is easier to hand solder and mount with a dedicated heat sink. The TO-220 package offers superior thermal conduction through its metal tab and is more forgiving thermally, allowing for smaller copper area on the PCB and simpler thermal management when running near the 3 A max current.
Input voltage range differences are notable. The LM2596T-3.3 supports a wider input voltage range starting as low as 1.2 V typical (±4%), allowing use in low-voltage battery or regulated supplies that dip below 4.5 V. The LM2596S-5.0 has a minimum input voltage of 4.5 V, limiting its use in such scenarios. This makes the LM2596T-3.3 more flexible in applications with wide or low input voltage sources.
Efficiency and quiescent current data are provided only for the LM2596T-3.3, indicating typical quiescent current of 5 mA and standby current of 80 μA. While the LM2596S-5.0 datasheet does not specify these explicitly, the overall efficiency and quiescent current are expected to be similar given the identical core topology. However, the lack of detailed efficiency curves for the LM2596S-5.0 means designers must verify experimentally or rely on typical LM2596 family performance.
Both devices operate at approximately 150 kHz switching frequency, standard for this family, which balances inductor size and switching losses. The LM2596T-3.3 datasheet notes a wide switching frequency range (110 kHz–2.2 MHz), but typical designs target 150 kHz. This impacts component selection and EMI considerations similarly.
Output voltage is fixed and different: 5 V for LM2596S-5.0 and 3.3 V for LM2596T-3.3. This is critical for system compatibility. The LM2596T-3.3 datasheet specifies output voltage tolerance of ±4%, ripple voltage of 62 mV p-p typical, and recommended output capacitor ESR of 0.1 Ω. The LM2596S-5.0 datasheet does not provide these numbers, requiring designers to validate output ripple and tolerance for their specific application.
From a cost perspective, the LM2596S-5.0 surface mount device typically costs more per unit than the through-hole LM2596T-3.3, but this depends on volume and supplier. The LM2596T-3.3’s through-hole package is often preferred in prototyping or low-volume production; the LM2596S-5.0 suits higher volume SMT production.