| Part Number | 72R040XU | 72R050XU | 
|---|---|---|
| Manufacturer | Littelfuse Inc. | Littelfuse Inc. | 
| Category | PTC Resettable Fuses | PTC Resettable Fuses | 
|   |   | |
| Product Status | Obsolete | Obsolete | 
| Type | Polymeric | Polymeric | 
| Voltage - Max | 72V | 72V | 
| Current - Max | 40 A | 40 A | 
| Current - Hold (Ih) (Max) | 400 mA | 500 mA | 
| Current - Trip (It) | 800 mA | 1 A | 
| Time to Trip | 3.8 s | 4 s | 
| Resistance - Initial (Ri) (Min) | 550 mOhms | 500 mOhms | 
| Resistance - Post Trip (R1) (Max) | 1.29 Ohms | 1.17 Ohms | 
| Resistance - 25°C (Typ) | - | - | 
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C | 
| Ratings | - | - | 
| Mounting Type | Through Hole | Through Hole | 
| Package / Case | Radial, Disc | Radial, Disc | 
| Size / Dimension | 0.299" Dia x 0.122" T (7.60mm x 3.10mm) | 0.311" Dia x 0.122" T (7.90mm x 3.10mm) | 
| Height - Seated (Max) | 0.532" (13.50mm) | 0.539" (13.70mm) | 
| Thickness (Max) | - | - | 
| Lead Spacing | 0.201" (5.10mm) | 0.201" (5.10mm) |