30 mA hold, 90 mA trip — the PTC that resets itself
The Littelfuse 0603L003/36YR is a polymeric PTC resettable fuse from the POLY-FUSE® 0603L series, designed to protect low-current signal and power lines in compact surface-mount assemblies. It holds 30 mA continuous without tripping and initiates a fault trip at 90 mA, with a typical time-to-trip of 1 second under fault conditions — fast enough to protect downstream ICs from sustained overcurrent without nuisance tripping on inrush. Rated for a maximum voltage of 36 V and a fault current capability of 40 A, this part covers USB bus protection, battery-charge paths, and low-voltage DC rails in portable and embedded equipment.
Resistance budget and thermal envelope
The operating temperature range spans -40 °C to 85 °C, covering industrial and consumer enclosures; the hold current derates at elevated ambient, so at 85 °C the effective hold current is roughly 70% of the 25 °C rating.
Package, approvals, and sourcing posture
Carries cURus and TUV agency approvals, confirming compliance with UL and IEC safety standards for overcurrent protection devices.