FJN4303RBU

Overview

The FJN4303RBU is an NPN epitaxial silicon pre-biased transistor manufactured by Fairchild Semiconductor. It integrates a single NPN transistor with built-in bias resistors in a TO-92 package. The device supports a maximum collector-emitter voltage of 50 V and a continuous collector current of 100 mA. It features a minimum DC current gain (hFE) of 56. The internal bias resistor network consists of R1 at 22 kΩ and R2 at 22 kΩ, resulting in a built-in bias resistor ratio of 1. The component is lead-free, RoHS compliant, and operates up to a maximum junction temperature of 150 °C.

Feature Summary

• Integrated dual bias resistors simplify circuit design for switching applications
• High thermal stability with a maximum operating temperature of 150 °C
• Lead-free construction ensuring compliance with environmental standards

Applications

• Switching circuits
• Inverter circuits
• Interface circuits
• Driver circuits

Procurement Notes

Verify the manufacturer origin, as Fairchild Semiconductor's discrete semiconductor division was acquired by onsemi. Confirm that the specific part number corresponds to the original Fairchild production run if legacy sourcing is required. Ensure the TO-92 package variant matches the pinout configuration specified in the official datasheet to prevent installation errors.

Selection Notes

Select this component when a compact solution for low-power switching or interface driving is needed without external base resistors. The equal 22 kΩ resistor values provide a balanced bias ratio suitable for standard logic interfacing. Compare against the complementary PNP type, such as the FJN4305RBU, if a positive-switching configuration is required instead of the NPN topology provided here.

Part Context

This component belongs to the FJN series of pre-biased transistors designed for surface-mount and through-hole applications requiring simplified drive circuits. It serves as a direct complement to other devices in the family, offering a standardized solution for replacing discrete transistor and resistor networks in consumer electronics and industrial control boards.

Replacement Considerations

The FJN3303RBU is documented as a functional complement within the same product line.