FJN4310RBU

Overview

The FJN4310RBU is a pre-biased NPN bipolar junction 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 50V and a continuous collector current of 100mA. Internal resistor values are specified as 4.7kΩ for the base resistor and 10kΩ for the emitter resistor, creating a fixed bias ratio of approximately 2.13. The component ensures a minimum DC current gain (hFE) of 30 and operates at temperatures up to 150°C.

Feature Summary

• Integrated dual-resistor network simplifies circuit design by eliminating external biasing components.
• Single-transistor configuration provides compact footprint within standard TO-92 packaging.
• Built-in biasing ensures consistent turn-on characteristics without complex drive requirements.

Applications

• General-purpose switching applications requiring simplified bias networks.
• Driver circuits for low-power loads where space constraints limit discrete component usage.
• Logic interface stages converting digital signals to higher current levels.

Procurement Notes

Verify the manufacturer origin and RoHS compliance status before procurement. Confirm that the TO-92 pinout matches the target schematic, as legacy Fairchild parts may have specific lead configurations. Ensure the integrated resistor tolerance meets the design requirements for the specific bias application.

Selection Notes

Select this component when a fixed bias ratio is acceptable and board space is limited. Compare the 4.7kΩ/10kΩ internal resistance against designs requiring adjustable gain. Verify that the 100mA current rating suffices for the load, as higher current options exist in other series.

Part Context

This part belongs to the FJN series of pre-biased transistors from Fairchild Semiconductor. These devices are designed to replace multiple discrete components, reducing assembly time and cost. The series typically includes various resistor ratios and transistor types to cover common logic interface needs.

Replacement Considerations

Check for direct equivalents with identical resistor values and hFE ranges. Verify pin compatibility in the TO-92 package to avoid rework. Consider if alternative manufacturers offer similar pre-biased configurations with updated supply chains.