15. PTC Fuse for Speaker Output Protection

If the speaker output is shorted or the amplifier clips at full power for a sustained period, the current can exceed safe levels for the speaker voice coil and amplifier output stage.

A PTC fuse in the speaker line trips on sustained overload, protecting both the speaker and amplifier. It resets automatically when the fault clears.

Current Calculation:

P = 10W, R = 4Ω. I = √(P/R) = √(10/4) = √2.5 ≈ 1.58A RMS

With 25–55% margin for thermal derating and dynamic peaks: Ih = 2.0A to 2.5A

Required: Polymeric · Ih 2.0–2.5A · ≥16V · Imax ≥10A · Through Hole · Littelfuse

Same category and similar filters as Task 2:

• Current - Hold (Ih) → 2.0A to 2.5A
• Voltage - Max → 16V or higher
• Mounting Type → Through Hole
• Manufacturer → Littelfuse Inc.

Tip: Audio amplifiers may have brief transient peaks well above the RMS current. The PTC’s thermal mass prevents it from tripping on short music peaks — it only trips on sustained overload lasting several seconds.

The filtered list will show matching parts. Before you pick one, check: Is it Active? Is stock available? Is the manufacturer reputable? Is a datasheet available?

Full checklist: How to Select a Safe, Production-Ready Component — EWskills Guide

➡ View Matching Parts — Littelfuse, PTC, Ih 2.0–2.5A, ≥16V, Through Hole