BC858B-HF

Overview

The BC858B-HF is a PNP bipolar junction transistor manufactured by Comchip Technology, designed for surface-mount applications. It utilizes silicon technology and is housed in an SOT-23-3 package. The device supports a continuous collector current of 100 mA with a maximum collector-emitter voltage (VCEO) of 30 V and a collector-base voltage (VCBO) of 30 V. The emitter-base voltage (VEBO) is rated at 5 V. Key electrical characteristics include a DC current gain (hFE) range of 420 to 800 and a transition frequency (fT) of 100 MHz. The saturation voltage is specified at 650 mV. Operating temperatures range from -55 °C to +150 °C.

Feature Summary

• PNP polarity configuration suitable for general-purpose switching and amplification tasks
• High DC current gain classification ensuring effective signal control with low base drive requirements
• Automotive-grade reliability standards integrated into the component design
• Compact SMD/SMT footprint facilitating automated assembly and space-constrained layouts

Applications

• General-purpose switching circuits in consumer electronics
• Amplifier stages requiring high gain PNP transistors
• Automotive electronic systems and modules
• Signal processing interfaces in industrial control equipment

Procurement Notes

Verify the specific hFE binning class required for your application, as the BC858B series typically denotes a higher gain range compared to standard variants. Confirm that the SOT-23-3 package dimensions align with your PCB footprint. Ensure compliance with RoHS directives if operating in regulated markets. Cross-reference the datasheet for thermal derating curves relevant to your enclosure environment. Validate supplier authenticity through authorized distribution channels to prevent counterfeit components.

Selection Notes

Select this component when a PNP transistor with a minimum hFE of 420 is necessary for efficient driver circuits. The 30 V rating suits low-voltage logic interfacing. Consider the SOT-23-3 package for limited board space. Compare against BC858A or BC858C if different gain thresholds are preferred. Evaluate thermal management needs given the 200 mW power dissipation limit in small packages. Ensure the 100 mA current capacity meets load requirements without exceeding safe operating areas.

Part Context

This part belongs to the widely used BC858 family of PNP transistors, which are industry-standard replacements for older discrete designs. Comchip Technology produces the HF variant, indicating halogen-free compliance. The BC858B designation specifically identifies the gain binning within this family. These devices are commonly found in portable battery-operated devices due to their low power consumption and small form factor.

Replacement Considerations

• BC858B
• MMBT3906

FAQ

What is the typical DC current gain range for the BC858B-HF?

The BC858B-HF features a DC current gain (hFE) range of 420 to 800, distinguishing it from lower-gain variants in the same package.

Is the BC858B-HF suitable for automotive applications?

Yes, the product description indicates it is an automotive-grade transistor, implying adherence to specific reliability standards for vehicle electronics.

What is the maximum collector-emitter voltage rating?

The maximum collector-emitter voltage (VCEO) is 30 V, making it suitable for low-voltage switching and amplification applications.