BC858A

Overview

The BC858A is a PNP silicon small-signal bipolar junction transistor (BJT) designed for general-purpose amplifier applications. It operates with a maximum collector current of 100 mA and a collector-emitter breakdown voltage of 30 V. The device features a DC current gain (hFE) range of 125 to 180, ensuring consistent amplification performance. It is housed in an SOT-23 surface-mount package, suitable for low-power designs. The component supports a maximum power dissipation of 250 mW and functions within a temperature range of -55°C to +150°C.

Feature Summary

• PNP polarity configuration for complementary switching and amplification circuits
• High DC current gain classification for stable signal processing
• Compact SOT-23 surface-mount packaging for space-constrained layouts

Applications

• General-purpose amplifier stages
• Switching applications requiring low power consumption
• Complementary pairs with NPN counterparts like the BC848 series

Procurement Notes

Verify the manufacturer designation on the component marking or datasheet, as multiple vendors produce this part number. Confirm RoHS compliance status if environmental regulations apply to your assembly process. Ensure the specific hFE binning matches your circuit requirements, as gain ranges vary by supplier. Check for automotive qualification markings if the application demands AEC-Q101 standards.

Selection Notes

Select the BC858A when a PNP transistor with moderate gain and 30V voltage rating is required. Compare the hFE minimum specifications across different manufacturers to ensure compatibility with your biasing network. Consider the SOT-23 footprint constraints during PCB layout. Verify thermal dissipation capabilities relative to your expected operating currents to prevent overheating.

Part Context

This component belongs to the BC858 family of PNP transistors, which are widely used in consumer electronics and industrial control systems. The 'A' suffix typically denotes a specific DC current gain bin, distinguishing it from 'B' or 'C' variants with higher gain thresholds. It serves as the PNP counterpart to the BC848 NPN transistor in many dual-transistor configurations.

Replacement Considerations

Direct substitutes include BC858B and BC858C, though their gain ranges differ. Cross-reference with BC857A or BC859A only if voltage or current ratings align with specific design needs. Verify pinout compatibility, as some generic replacements may follow different lead configurations.