BCX56 BCX56-16 BL P11 NPN Medium Power Transistor Whatsminer PSU Repair

BCX56 / BCX56-16 BL P11 NPN Medium-Power Transistor | SOT-89 for Whatsminer P21 PSU Repair

The BCX56-16 / BL P11 is an NPN medium-power bipolar transistor in the SOT-89 SMD package — the small signal / driver transistor used on the Whatsminer P21 power supply unit control circuit. Drop-in replacement when the original fails after a transient event or extended thermal stress.

Headline specs: 80V max VCEO, 1A max IC, 500mW total power dissipation, hFE 63–250, fT 100MHz minimum. The compact SOT-89 footprint integrates an exposed heatsink tab for direct thermal coupling to the PCB copper — handles continuous switching duty in the PSU's bias and drive stages.

When to Replace the BCX56-16

• PSU fails to start — driver transistor open or shorted, controller cannot enable downstream MOSFETs.
• Audible squealing or coil whine not present in normal operation — driver bias drift causing erratic switching.
• Visible damage on the SOT-89 package — burnt, cracked, or discoloured after a fault event.
• Excessive base-emitter leakage measured with a curve tracer or DMM on the suspect device.

BCX56-16 Transistor Specifications

FAQ — BCX56-16 Transistor

Q: BCX56 vs BCX56-10 vs BCX56-16 — which one do I need?
A: The dash-number is the hFE grade. -10 = 40–100, -16 = 63–250, -25 = 160–400. The Whatsminer P21 PSU uses the -16 grade specifically. Match the silk marking ("BL P11" → -16 grade) when replacing.

Q: How do I test the suspect transistor in-circuit?
A: Power off, isolate at least one lead from the board to avoid back-feed through surrounding components. Use a DMM diode-test mode: ~0.6V forward drop B→E and B→C, infinite C→E in both directions. Failed transistors show shorts or opens on these junctions.

Q: Rework profile?
A: SOT-89 has the exposed heat tab soldered to the PCB pad — needs full preheat and adequate hot-air dwell to release the thermal joint. Preheat to 100°C, hot air at 320°C with flux paste, allow extra dwell vs a standard SOT-23.

Q: Bulk pricing?
A: Yes — email contact@lys-sz.com for tape-and-reel quantities of BCX56-16 stock.

Related products

• LM2904DR2G Dual Op-Amp (Whatsminer P21 PSU)
• LM358DR Dual Op-Amp (Whatsminer PSU)
• LM321A-TR Single Op-Amp (Whatsminer)
• SLM346 Isolated Gate Driver (Whatsminer P221 / P222)

Whatsminer PSU repair benches stocking BCX56-16 in tape-and-reel volume? Email contact@lys-sz.com for bulk pricing. Worldwide shipping from our Shenzhen warehouse.