12. PPTC Selection & Failures cases

Question.3

Robert used Littelfuse 1210L600SLWR PPTC (DigiKey Part Number: F11790CT-ND) for a 12V battery-powered application.
Application load current is 2A max, and in a short circuit, up to 40A can flow.
The PPTC has I_hold = 6A and I_max = 50A fault current capability.
Yet the PPTC burned during a short circuit event.
Help poor Robert — what's the issue?
Note — Refer to the datasheet from DigiKey — click here.

I_hold is too high — the PPTC never tripped and allowed the short circuit current to flow continuously
The maximum voltage rating (V_max) of the PPTC is lower than the 12V system voltage
The 1210 package is too small for 12V applications — a 2920 package is required
The R_initial is too high, causing the PPTC to overheat during normal 2A operation

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