LM2596T-ADJ/NOPB vs. LM2596S-3.3-EV: A Practical Comparison
Quick verdict: For applications requiring a highly customizable output voltage and a through-hole package, the LM2596T-ADJ/NOPB is the clear winner. However, if a fixed 3.3V output simplifies your design and you prefer surface mount, the LM2596S-3.3-EV offers a quicker path to a working prototype, but with less flexibility.
Spec comparison table
| Spec | LM2596T-ADJ/NOPB | LM2596S-3.3-EV | Notes |
|---|---|---|---|
| Function | Step-Down | Step-Down | Identical |
| Output Configuration | Positive | Positive | Identical |
| Topology | Buck | Buck | Identical |
| Output Type | Adjustable | Fixed | ADJ offers flexibility, fixed simplifies design. |
| Number of Outputs | 1 | 1 | Identical |
| Input Voltage Min | 4.5V | - | LM2596T-ADJ/NOPB has a lower minimum input voltage. |
| Input Voltage Max | 40V | 40V | Identical |
| Output Voltage Min | 1.2V | 3.3V | ADJ offers a wider range. |
| Output Voltage Max | 37V | - | ADJ offers a wider range. |
| Output Current Max | 3A | 3A | Identical, but note that the EVVO part’s datasheet states a max of 2A for the regulated output voltage. |
| Switching Frequency Typ | 150kHz | 150kHz | Identical |
| Synchronous Rectifier | No | No | Identical |
| Operating Temperature Range | -40°C ~ 125°C | -40°C ~ 125°C | Identical |
| Mounting Type | Through Hole | Surface Mount | TH is easier for prototypes; SM is better for dense boards. |
| Package Case | TO-220-5 Formed Leads | TO-263-6, D2PAK (5 Leads + Tab), TO-263BA | TO-220 is easier to hand-solder; D2PAK/TO-263 are better for automated assembly. |
| Supplier Device Package | TO-220-5 | TO-263-5L | Different footprint – requires PCB redesign. |
| Input Voltage Range | Up to 100/10V | Up to 25V | LM2596T-ADJ/NOPB has a wider input voltage range |
| Output Current Typ | 3A | 2A | The EVVO part’s datasheet states a max of 2A for the regulated output voltage. |
| Input Voltage Range HV | 57V | - | LM2596T-ADJ/NOPB has a higher input voltage range |
| Output Current Load Max | +4% max over line and load conditions | - | LM2596T-ADJ/NOPB has a higher output current load max |
| Oscillator Frequency Typ | 150kHz | 25 kHz | LM2596T-ADJ/NOPB has a higher oscillator frequency |
| Shutdown Current Typ | typically 80µA | - | LM2596T-ADJ/NOPB has a higher shutdown current |
| Temperature Range | -40°C ≤ T ≤ 125°C | -40°C ≤ T ≤ 125°C | Identical |
| Output Voltage | 180/35 V | 3.3V | ADJ offers a wider range |
| Input Voltage | 100/10 V | 25V | ADJ offers a wider range |
| Output Capacitor | 820/35 µF/V | - | ADJ offers a wider range |
| Input Capacitor | 470/4 µF/V | - | ADJ offers a wider range |
| Inductor | 68µH | 33µH | LM2596T-ADJ/NOPB requires a larger inductor. |
| Output Voltage Min | 180/35 V | 3.5V | ADJ offers a wider range |
| Input Voltage Min | 100/10 V | 25V | ADJ offers a wider range |
| Regulated Output Voltage | 20V | 3.3V | Fixed simplifies design. |
| Maximum Input Voltage | 28V | 25V | LM2596T-ADJ/NOPB has a higher input voltage |
| Maximum Load Current | 3A | 4.5A | LM2596T-ADJ/NOPB has a higher output current |
| Input Capacitor RMS Current Rating Max | - | - | |
| Ground Pin Voltage | - | - | |
| Package Dimension TO220B-5L | - | - |
Design trade-offs
The most significant difference lies in the adjustable output versus the fixed 3.3V. The ADJ version’s flexibility is invaluable when designing systems requiring varying voltage rails or needing to accommodate component tolerances that shift the operating voltage. However, this flexibility comes at the cost of increased design complexity. You must carefully select external resistors and verify their stability over temperature and load variations. The fixed 3.3V version simplifies the design process considerably, eliminating the need for external feedback components and reducing the potential for errors.
The through-hole package of the LM2596T-ADJ/NOPB is a boon for prototyping and low-volume production, allowing for easy manual soldering. The surface mount options of the LM2596S-3.3-EV are better suited for high-volume production and designs with limited board space, but require more sophisticated assembly techniques. The inductor and capacitor values will differ based on the output voltage and current requirements, necessitating different external components. The LM2596T-ADJ/NOPB requires a larger inductor due to the adjustable output voltage, which can impact board layout.
Thermal considerations are similar for both parts, given their identical power dissipation characteristics. However, the larger TO-220 package of the ADJ version may provide slightly better heat dissipation in some applications. Gate drive requirements are standard for both, relying on the internal driver to control the external MOSFETs. Layout sensitivity is moderate for both, but the adjustable version requires careful attention to feedback loop trace impedance to prevent oscillations.
Use-case fit
Choose LM2596T-ADJ/NOPB when…
- You need to generate multiple voltage rails from a single input voltage, such as powering both a microcontroller and an analog sensor.
- You are prototyping a new design and need the flexibility to adjust the output voltage to optimize performance.
- You are working with a legacy system that requires a specific voltage that is not readily available from a fixed-output regulator.
- You are designing a low-volume production run and prefer the ease of through-hole soldering.
- You need to generate a higher output voltage than the fixed 3.3V version can provide.
Choose LM2596S-3.3-EV when…
- You need a simple and reliable 3.3V power supply for a microcontroller or other digital circuit.
- You are designing a high-volume production run and want to minimize assembly costs.
- You have limited board space and need a compact power supply solution.
- You want to reduce design complexity and eliminate the need for external feedback components.
- You are creating a quick prototype and want to get a working design up and running quickly.
Drop-in compatibility
The LM2596T-ADJ/NOPB and LM2596S-3.3-EV are not pin-compatible. The pinout is the same, but the package footprints are different, requiring a PCB redesign. The external component values (inductor, feedback resistors) will also need to be recalculated for the fixed-output version. The regulated output voltage of the EVVO part is 2A, whereas the ADJ version is 3A.
Alternatives to consider
- LM2596-5.0: A fixed 5.0V version, offering a different output voltage option.
- TPS5430: A synchronous buck converter offering higher efficiency.
- LM317: An adjustable linear regulator, suitable for low-power applications where efficiency is not a primary concern.
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