parts sub

[Hexhclass]

Which on of these can be a better sub to replace MMBT5087

https://www.fairchildsemi.com/datasheets/MM/MMBT5087.pdf



https://www.fairchildsemi.com/datasheets/MM/MMBT5401.pdf

https://www.fairchildsemi.com/datasheets/MM/MMBTA56.pdf

https://www.fairchildsemi.com/datasheets/MM/MMBTA92.pdf

https://www.fairchildsemi.com/datasheets/MM/MMBT4403.pdf

 

[ultra]

i would go for BC857 http://cache.nxp.com/documents/data_sheet/BC856_BC857_BC858.pdf?pspll=1

 

[Hexhclass]

Trying to work with what i have in stock.

 

[Perry Babin]

How is it being used?

 

[Hexhclass]

In the class D section


base connects to pin 5 of driver IC
emitter connects to pin 3 of driver IC
collector connect to source leg of output FET

http://www.infineon.com/dgdl/irs20124s.pdf?fileId=5546d462533600a401535675ca352786

http://www.infineon.com/dgdl/irfb4115pbf.pdf?fileId=5546d462533600a401535615ba6a1e0f

 

[Perry Babin]

I can't help choose a sub. I am not familiar with the IC. If it's in the over-current protection circuit, the high-gain of the original may be important to the protection of the amplifier.

 

[Hexhclass]

I will order the original.Can i used anyone for test?

 

[Perry Babin]

All of the ones you listed are better in current and voltage ratings. The DC current gain is where they're lacking. They should easily survive but they may not allow the protection circuit to function properly.

Maybe someone with a better understanding of the IC could offer a more definitive answer.