SG421

Inrush Current Limiters (ICL) Overview

The SG421 is a Negative Temperature Coefficient (NTC) thermistor inrush current limiter from the SURGE-GARD series. It features a nominal resistance of 17.5 Ohms and a steady-state current rating of 4 A. The component supports a maximum voltage of 265 VAC with a tolerance of 15%. Designed for PCB mounting, it utilizes radial straight leads with a 0.500-inch spacing. The unit operates within a temperature range of 0°C to +65°C.

Inrush Current Limiters (ICL) Feature Summary

• Provides high initial resistance to limit inrush current during power-up
• Automatically reduces resistance as temperature increases during operation
• Radial lead configuration facilitates through-hole PCB integration

Inrush Current Limiters (ICL) Applications

• Power supply input stages
• Transformer primary circuits
• Capacitor charging protection

Inrush Current Limiters (ICL) Procurement Notes

Verify the specific ordering suffix against the manufacturer datasheet to confirm lead type and package variations. Ensure the selected variant matches the required voltage and current ratings for the target application circuit. Confirm RoHS compliance status if restricted substances are prohibited in the design.

Inrush Current Limiters (ICL) Selection Notes

Select this component based on the peak inrush current magnitude and the steady-state operating current requirements. Verify that the 17.5 Ohm cold resistance provides sufficient limiting without excessive voltage drop. Check thermal stability and maximum energy absorption capabilities relative to the circuit capacitance.

Inrush Current Limiters (ICL) Part Context

This part belongs to the Vishay Ametherm SURGE-GARD SG series of NTC thermistors. These components are engineered specifically for protecting electronic equipment from damaging surge currents. The series offers various resistance and current ratings to suit different power levels.

Inrush Current Limiters (ICL) Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation.