0456040.DR SMD fuse: Complete datasheet & critical specs

2026-01-23 12:33:33

As board-level power densities rise across automotive, telecom, and battery systems, designers increasingly choose compact high-current SMD protection. The 0456040.DR is a common 40 A / 60 VDC NANO²-format option that balances size and interrupting capability.

This guide unpacks the datasheet, highlights electrical and thermal limits, and provides an actionable selection checklist so engineers can validate the part quickly and reduce risk during prototyping and production. We focus on measurable specs, practical calculations (V_drop and power loss), and PCB/assembly guidance for reliable SMD fuse deployment.

Product Overview & Key Specifications

0456040.DR SMD fuse: Complete datasheet & critical specs

Part Identity, Package and Footprint

The part code 0456040.DR identifies a NANO² / square SMD block rated for 40 A continuous at low ambient temperatures and 60 VDC nominal.

Dimension	Typical (mm)
Length (L)	7.3
Width (W)	6.0
Height (H)	2.9

Recommended PCB pad geometry: two rectangular pads matching the device terminals with a solder mask opening slightly undersized for paste-stencil control. Use a 0.12–0.15 mm solder paste coverage on terminal areas to balance fillet formation and tombstoning risk. For thermal relief, avoid overly small pad-to-copper transitions under the device.

At-a-glance Electrical Summary

Parameter	Typical Value	Units
Rated current	40	A
Rated voltage	60	V DC
Interrupting rating (example)	150–600	A (varies)
Characteristic	Fast-acting	—

Electrical Characteristics & Performance Curves

Time-current Behavior and Fusing Characteristics

Time-current (T–I) curves show clearing time versus multiple of rated current and are the primary tool for coordination. Read the curve by locating the prospective fault current on the horizontal axis and tracing upward to the curve to find clearing time. For protection selection, choose a pick current that clears fast for sustained overloads but allows short inrush events without nuisance open.

Design Checkpoints: Annotate the datasheet T–I curve to mark (1) expected inrush current magnitude/duration and (2) maximum sustainable overload before fuse clearing. Maintain at least 20–30% margin.

Interrupting Rating, I²t and Energy Withstand

Interrupting rating (IR) denotes the maximum prospective fault current the fuse can safely interrupt. When I²t is listed, use it to compare the energy let-through against upstream protection—lower I²t reduces stress on wiring and downstream components.

Thermal Behavior, Resistance & Derating

DC cold resistance for this class of SMD fuse is typically in the single-digit milliohm range. Power loss scales exponentially with current (P = I²R), making thermal management critical.

Power Loss Visualization (at R = 2.5 mΩ)

10 A

0.25 W

20 A

1.00 W

30 A

2.25 W

40 A

4.00 W

Ambient Derating

Derating curves show reduced continuous current capacity as PCB temperature rises. Increase copper area and add thermal vias to dissipate heat; a double-sided heavy-copper plane under the fuse raises continuous capacity significantly.

Verification Tip

Validate with IR thermography and measure hotspot temperatures during representative current profiles to confirm safe operation within the fuse's thermal limits.

Reliability, Testing & Compliance

Confirm thermal shock & mechanical vibration ratings
Check solderability and recommended reflow profiles
Verify surge and life-cycle test pass/fail criteria
Search for agency recognition (UL/CSA/VDE)
Map ratings to specific applications (Battery/Telecom)
Confirm DC interrupting capability for energy packs

Datasheet Reading & Assembly Guidance

Quick-Check Steps

Confirm full part code and revision
Verify rated I, V, and Interrupting Rating
Inspect T–I and derating curves
Check mechanical drawing/land pattern
Review recommended reflow profile
Note storage and moisture sensitivity

Assembly Best Practices

Follow peak reflow temp and time-above-liquidus. Use controlled cooling to avoid thermal shock. Post-reflow, inspect solder fillets for wetting and planarity. Perform continuity checks before full system power-up.

Selection Checklist & Troubleshooting

Common Failure Modes

Open-circuit from unexpected overcurrent
Thermal degradation from poor heat sinking
Failed solder joints due to thermal expansion
Nuisance blowing from high-energy inrush

Selection Factors

Current margin (typical 25–50%)
Verified Interrupting Rating for voltage
DC resistance and resulting power loss
Package footprint compatibility
Thermal derating for your specific PCB

Frequently Asked Questions

Is the 0456040.DR suitable for battery-pack protection? +

Yes for many designs if the datasheet lists a DC interrupting rating that exceeds expected fault currents and the PCB thermal management supports continuous 40 A. Confirm the DC-specific IR and perform high-current fault tests in your application to validate safe clearing and energy let-through.

How should I verify Vdrop and power loss for an SMD fuse in my design? +

Measure the device cold resistance and calculate Vdrop = I × R and P = I²R at expected operating currents. Validate with in-situ measurements on a populated board and use IR thermography to confirm temperatures under continuous load.

What PCB layout practices improve SMD fuse thermal performance? +

Maximize plane copper under the device, add thermal vias to inner layers, avoid cutouts under terminals, and use wide traces to reduce secondary heating. These measures lower ambient rise and increase allowable continuous current per the datasheet derating curves.

Summary

0456040.DR is a compact 40 A / 60 VDC SMD fuse; verify the exact interrupting rating on the official datasheet before production.
Critical Checks: T–I curves, protection margins, interrupting rating / I²t values, and thermal derating relative to PCB copper.
Procurement: Use the supplied quick-check to confirm mechanical, electrical, and environmental test coverage for production readiness.

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