Comparison: LM2596S-ADJ/NOPB vs LM2596T-12

Quick verdict

For designs requiring a flexible output voltage and compact surface-mount assembly, the LM2596S-ADJ/NOPB is the clear choice, offering adjustable output from 1.2 V to 37 V and a D2PAK surface-mount package. For applications with a fixed 12 V output and where through-hole mounting or easier manual assembly is preferred, the LM2596T-12 is more appropriate, providing a fixed, stable 12 V output in a TO-220 package with better thermal dissipation potential.

Spec comparison table

SpecLM2596S-ADJ/NOPBLM2596T-12Notes
FunctionStep-DownStep-DownEqual
Input Voltage Max40 V40 VEqual
Input Voltage Min4.5 VNot explicitly defined (typical min ~15V)LM2596S-ADJ allows lower input voltage operation (4.5 V vs ~15 V), better for low-voltage rails
Output ConfigurationPositivePositiveEqual
Output TypeAdjustableFixed 12 VAdjustable output is more flexible for custom voltage rails
Number of Outputs11Equal
Output Voltage Min1.2 V12 VAdjustable part supports lower voltages
Output Voltage Max37 VNot specifiedAdjustable part supports wider output voltage range
Output Current Max3 A3 AEqual
Switching Frequency Typ150 kHz150 kHzEqual
Synchronous RectifierNoNoEqual
TopologyBuckBuckEqual
Mounting TypeSurface Mount (TO-263, D2PAK)Through Hole (TO-220)TO-263 better for automated assembly, TO-220 better for hand assembly and heat sinking
Package CaseTO-263-6, D2PAK (5 Leads + Tab)TO-220-5TO-220 offers lower thermal resistance (5 °C/W vs ~70 °C/W junction-to-ambient)
Supplier Device PackageTO-263 (DDPAK-5)TO-220-5LSee above
Operating Temperature Range (TJ)-40°C to 125°C-40°C to 125°CEqual
Overshoot Voltage TypNot specified±4%Fixed output part specifies output overshoot, useful for tighter voltage margin design
Input Current TypNot specified3 ASimilar, but LM2596T-12 datasheet more explicit
Saturation Voltage Typ~1.5 V (typical)1.5 V (typical)Equal
Threshold Voltage Typ1.3 V (typical)1.3 V (typical)Equal
Quiescent Current TypNot specified5 mALM2596T-12 provides explicit quiescent current spec
Standby Quiescent Current TypNot specified200 µALM2596T-12 has standby mode current data
Thermal Resistance Junction-to-Ambient~70 °C/W (TO-263)65 °C/W (TO-220)TO-220 package typically better heatsinking potential
Thermal Resistance Junction-to-Case~5 °C/W5 °C/WEqual
Shutdown Current TypNot specified80 µALM2596T-12 datasheet provides shutdown current info
Storage Temperature RangeNot specified-60°C to +150°CLM2596T-12 provides wider storage temp range
Maximum Junction TemperatureNot specified150°CLM2596T-12 explicit, likely equal
On/Off Pin Logic Input Level TypNot specified1.3 VLM2596T-12 documents on/off pin levels, useful for firmware control
Output Leakage Current TypNot specified25 µALM2596T-12 provides leakage current data
Max Duty CycleNot specified100%LM2596T-12 data more complete

Design trade-offs

The LM2596S-ADJ/NOPB and LM2596T-12 are functionally similar buck regulators with a maximum output current of 3 A and nominal switching frequency of 150 kHz. The primary design trade-off between these devices lies in output voltage flexibility, package type, and thermal management.

The LM2596S-ADJ/NOPB supports adjustable output voltage from 1.2 V to 37 V, enabling use in a wide range of custom voltage rails. This flexibility is critical for designs requiring non-standard voltages or dynamic voltage scaling. However, this advantage comes with additional external components (resistor divider for feedback) and slightly more complex calibration and layout considerations.

Conversely, the LM2596T-12 provides a fixed 12 V output, simplifying design and reducing BOM complexity. Fixed output versions often exhibit tighter voltage accuracy and well-characterized overshoot and transient response (±4% typical overshoot voltage). For designs with standard 12 V rails, this fixed output choice reduces design risk.

Thermally, the LM2596T-12’s TO-220-5 package offers significantly better heat dissipation than the LM2596S-ADJ’s TO-263 surface-mount package. The junction-to-ambient thermal resistance of approximately 65 °C/W versus around 70 °C/W for the TO-263, combined with the larger exposed tab and easier attachment to a heatsink, makes the LM2596T-12 better suited for applications with higher ambient temperatures or constrained airflow. The LM2596S-ADJ is more compact and suited for automated assembly but requires careful PCB thermal design, including large copper pours and possibly additional thermal vias.

From a firmware perspective, the LM2596T-12 datasheet provides explicit on/off control pin voltage levels and current consumption (standby ~200 µA, shutdown ~80 µA), useful for power management and sequencing. The LM2596S-ADJ datasheet lacks these specifics, which may complicate low-power control strategies.

Cost-wise, surface-mount LM2596S-ADJ devices typically have lower per-unit costs in volume and are more compatible with modern assembly lines. The LM2596T-12’s through-hole package is generally more expensive per unit and less suitable for high-volume automated manufacturing but easier to prototype with.

Use-case fit

Choose LM2596S-ADJ/NOPB when…

Choose LM2596T-12 when…

Drop-in compatibility

These two devices are not pin-compatible nor footprint-compatible:

The difference in packages means PCB footprint changes are mandatory. Additionally, the adjustable version requires external resistors for setting output voltage; the fixed 12 V version does not. Substituting one for the other requires redesigning feedback and layout, and verifying thermal management.

Alternatives to consider