PPTC Fuse for DC Motor Stall Protection

Question

Problem: PPTC Fuse for DC Motor Stall Protection. Solve this hands-on electronics task on EWskills.

Accepted Answer

1. Component Purpose & Calculation

When a DC motor stalls (mechanical jam), it draws several times its normal current — continuously. This sustained overcurrent can burn the motor windings, overheat the driver IC, and damage PCB traces.

A PTC fuse in series with the motor supply trips during sustained stall current but holds during normal running. When the jam is cleared and the motor restarts, the PTC cools and resets.

Hold Current Selection:

Normal current = 1.5A. With ~25% thermal derating margin: Ih range = 1.85A to 2.5A. Trip current (~2× Ih) would be 3.7A–5A, which catches a 5A stall condition.

Required: Polymeric · Ih 1.85–2.5A · ≥16V · Imax ≥10A · Through Hole · Littelfuse

2. How to Find It on DigiKey

Go to DigiKey.com → Circuit Protection → PTC Resettable Fuses

Apply these filters:

Current - Hold (Ih) → 1.85A to 2.5A range
Voltage - Max → 16V or higher
Mounting Type → Through Hole
Manufacturer → Littelfuse Inc.
Part Status → Active

Important: PTC fuses have a response time of seconds — they are NOT fast-acting. For motor stall protection this is acceptable because the stall condition is sustained. For fast short-circuit protection, use a regular fuse upstream.

3. Key Specifications & What They Mean

Specification	Required	Why
Type	Polymeric	Standard resettable PTC.
Hold Current	1.85–2.5A	Normal 1.5A + derating margin.
Voltage Max	≥16V	Exceeds 12V supply + inductive spikes.
Current Max	≥10A	Survives motor stall fault current.
Mounting	Through Hole	Robust for motor power path.
Manufacturer	Littelfuse	Company AVL requirement.
Temp Range	−40°C to +85°C	Warm enclosure conditions.
RoHS	Yes	Compliance required.

4. Selecting a Safe, Production-Ready Part

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

5. Filtered DigiKey Link

➡ View Matching Parts — Littelfuse, PTC, Ih 1.85–2.5A, ≥16V, Through Hole

14. PPTC Fuse for DC Motor Stall Protection