N_Cook wrote:


With the built in temp comp diodes, 1 silicon in the N type and 5
Schotky in the P and mirror-reversed pinning .
Owner put a short across one speaker line, magic smoke but other channel
is normal. Internal emitter resistor .22R of the p type is now not .22R.
I intend removing both , of the failed channel , to check out of
circuit, but anyone jumpered in an external .2R in these circumstances
and no further problems from cracked die etc as this R is part of the die?


** The 0.22 ohm is not part of the die, but a separate thick film resistor as stated in the Sanken data.


The datasheet I think , in fractured English, says the thermal safe
operating over-current zone, for the built in .22R is deliberately
lower than the Darlington itself.


** The max current rating of the 0.22ohm is somewhat less than the Darlington itself - but this is not deliberate, just a practical limitation. If the internal resistor has failed, the Darlington may still be OK.

Designers can use an external WW resistor if needed, or add a current limiter circuit that protects the inbuilt one.

I have seen a lot of these devices used in powered speakers made by dB Technologies - their "Opera" series and others.

The "English" in the app notes is bloody dreadful.



..... Phil