LM2596S-ADJ/NOPB vs 400LMMT: Component Comparison for Power Electronics Engineers
Quick verdict
For DC-DC voltage regulation in low- to medium-current applications (up to 3A), the LM2596S-ADJ/NOPB is the clear choice due to its integrated switching regulator functionality, adjustable output, and manageable thermal profile. Conversely, the 400LMMT fuse is designed for high-current (6A to 900A) AC/DC protection, making it indispensable for industrial power distribution and fault current interruption, not for voltage regulation or power conversion.
Spec comparison table
| Spec | LM2596S-ADJ/NOPB | 400LMMT | Notes |
|---|---|---|---|
| Function | Step-Down Buck Switching Regulator IC | Industrial & Electrical Thyristor Fuse | Different device categories; regulator vs. fuse. LM2596S regulates voltage, 400LMMT protects circuits. |
| Input Voltage Max | 40 V | 660 V | 400LMMT handles much higher voltages; critical for high-voltage protection applications. |
| Input Voltage Min | 4.5 V | 50 V AC (min) | LM2596S supports low voltage DC inputs; 400LMMT rated for higher AC/DC voltages. |
| Mounting Type | Surface Mount | Through-Hole (assumed from stud height) | LM2596S is SMD; 400LMMT is likely panel or chassis mount with studs, affecting assembly. |
| Number of Outputs | 1 | 1 | Both single output, but different function (regulated output vs. fuse pass-through). |
| Operating Temperature Range | -40°C to 125°C (TJ) | Not explicitly stated | LM2596S thermal rating is explicit; fuse datasheet lacks thermal range, typical for fuses. |
| Output Configuration | Positive | N/A | LM2596S outputs regulated positive voltage; fuse does not output voltage. |
| Output Current Max | 3 A | 6 A (min) to 900 A (typ) | 400LMMT supports much higher currents for protection; LM2596S limited to 3 A regulation. |
| Output Type | Adjustable | N/A | LM2596S output voltage is adjustable; fuse is passive. |
| Output Voltage Max | 37 V | N/A | LM2596S adjustable output voltage up to 37 V; fuse does not regulate voltage. |
| Output Voltage Min | 1.2 V | N/A | LM2596S minimum adjustable voltage; not applicable for fuse. |
| Package / Case | TO-263-6, D2PAK (5 Leads + Tab) | Stud-mounted fuse (1” to 1.75” height) | LM2596S is a compact SMD package; 400LMMT requires mechanical mounting with studs. |
| Supplier Device Package | TO-263 (DDPAK-5) | N/A | Confirms LM2596S standard SMD package. |
| Switching Frequency Typ | 150 kHz | 6 Hz (typ) | LM2596S switching frequency relevant for switching regulator operation; 400LMMT fuse switching is irrelevant or related to fault clearing speed. |
| Synchronous Rectifier | No | N/A | LM2596S does not include synchronous rectification; fuse is passive component. |
| Topology | Buck | N/A | LM2596S is a buck converter IC; fuse is not a power converter. |
| Base Voltage (1BS101) | N/A | 600 V | 400LMMT fuse rated for high voltage protection. |
| Carton Qty Min | N/A | 20 | Ordering quantity consideration; fuse typically ordered in bulk. |
| Carton Weight Min | N/A | 0.110 kg | Mechanical handling consideration for fuses. |
| Carton Weight Typ | N/A | 0.110 kg | Same as above. |
| Current Rating (1BS101) | N/A | 100 A | Fuse can handle very high currents; regulator limited to 3A output current. |
| Current Rating Min | N/A | 6 A | Fuse minimum current rating for protection purposes. |
| Current Rating Typ | N/A | 6 - 900 A | Wide fuse current rating range, suitable for many industrial scenarios. |
| I²t Rating Min | N/A | Not specified | Important for fuse energy let-through, but data missing. |
| Interrupting Rating Min | N/A | 200 kA RMS Symmetrical | High interrupt capacity protects against severe fault currents. |
| Interrupting Rating Typ | N/A | 200 kA RMS Symmetrical | Same as above. |
| Max Working Voltage (Contact-to-Contact RMS) | N/A | 1000 V | High voltage isolation capability for fuse. |
| Max Working Voltage (Contact-to-Contact RMS 1500V) | N/A | 1500 V | Higher voltage rating for specialized applications. |
| Microswitch Attachment Ratings (Various) | N/A | 0.7 - 6 A depending on voltage/load | Relevant to fuse trip indication accessories, not applicable to regulator. |
| Output Power Max | N/A | 220 W | Fuse power dissipation at rated current; regulator power depends on load and efficiency. |
| Rated Current Clearing at 120 V | N/A | 6 - 2 A max | Fuse clearing current rating at low voltage AC. |
| Rated Current Clearing at 240 V | N/A | 10 - 3.8 A max | Fuse clearing current rating at higher AC voltage. |
| Rated Current Min | N/A | 1.8 A | Fuse minimum rated current. |
| Rated Current Typ | N/A | 10 A | Typical fuse rating. |
| Rating IEC | N/A | 350 V DC (IEC) | Fuse DC voltage rating per IEC standard. |
| Stud Height (Various) | N/A | 0.75” to 1.75” | Mechanical mounting dimension for fuses; impacts enclosure design. |
| Trip Indicator Fuselink Max Ratings | N/A | 37.6 - 198.3 A²s | Fuse energy let-through rating for different trip indicators. |
| Voltage AC Min | N/A | 50 V AC | Fuse minimum AC voltage rating. |
| Voltage DC Typ | N/A | 75 - 1500 V DC | Wide DC voltage rating range for fuse. |
| Voltage Rating AC Min | N/A | 240 Vac | Fuse minimum AC voltage rating. |
| Voltage Rating AC Typ | N/A | 240 Vac / 150 V DC | Typical fuse voltage rating. |
| Voltage Rating DC Min | N/A | 150 V DC | Fuse minimum DC voltage rating. |
| Voltage Rating DC Typ | N/A | 240 Vac / 150 V DC | Typical fuse DC rating. |
| Watt Loss at Rated Current Min | N/A | 1.0 W | Fuse power dissipation at rated current affects thermal design. |
| Watt Loss at Rated Current Typ | N/A | 2.5 W | Fuse typical power loss at rated current. |
| Working Voltage E-G RMS Max | N/A | 250 V | Fuse isolation voltage to ground. |
| Working Voltage E-G RMS Min | N/A | 200 V | Fuse isolation voltage to ground minimum. |
| Working Voltage E-G RMS Typ | N/A | 240 V | Typical fuse isolation voltage to ground. |
Design trade-offs
The LM2596S-ADJ/NOPB and 400LMMT serve fundamentally different roles in power electronics: the former is a DC-DC buck converter IC designed for voltage regulation, the latter is a high-current fuse intended for circuit protection. This makes direct functional comparison somewhat orthogonal, but understanding their design implications is critical.
From a layout perspective, the LM2596S is a surface-mount device in a TO-263 package, requiring careful thermal management on the PCB. Its maximum output current of 3A limits its use to low-to-medium power applications. The 150 kHz switching frequency allows relatively small inductors and capacitors, but also demands careful layout to minimize EMI and switching losses. The lack of synchronous rectification means efficiency typically peaks in the 70–80% range depending on load and input voltage, so thermal dissipation must be planned accordingly.
The 400LMMT fuse is a mechanically robust, stud-mounted component designed for interrupting currents up to 200 kA RMS symmetrical and rated voltages up to 660 V (input voltage max 660 V, interrupting rating min 200 kA RMS). Its power dissipation at rated current (1.0–2.5 W) and physical size (stud heights up to 1.75”) require substantial space and thermal clearance in industrial en