SAP15P Datasheet, PDF (5/6 Pages) Sanken electric – Darlington transistors with built-in temperature compensation diodes for audio amplifier applications

5. Destruction capacity of the built-in emitter resistor
The built-in resistor is fabricated with polysilicone on the chip for the SAP08P/N and a thick-film resistor is
used for the SAP10P/N and SAP15P/N. The latter, the thick-film resistor, has weaker destruction point in
the Pc area (especially for large current flowing area) rather than that of the transistor chip itself. This is
subject to the area beyond Safe Operating Area (S.O.A).
However, under the evaluation like a short circuit test in which the current exceeds the guaranteed value, it
may cause the emitter resistor to be destroyed before the transistor itself is destroyed.
Consequently, the current value (or time) that operates the protection circuit is to be set at lower than that of
discrete device configurations. In the application of car audio amplifiers, the same manners as the above
need to be considered because the large current is flowed at low impedance.
In addition, once the transistor falls into thermal runaway due to a soldering failure to the external VR added
between diodes or other failure manners, as the worst case, there may cause a resin crack or smoke emissions
by flare up. Flame retardant molding resin is used, and the material of the product is conformed to the most
sever standard UL94V0. However it is recommended that the careful consideration be given to a protection
circuit, and the protection circuits should be provided appropriately in due course.
If the operating conditions are not to be matched to the ratings, it is also recommended that the E (Emitter
resistor) terminal should be opened and the external emitter resistor should be added to the S (Sensing)
terminal shown as below. (However this is not applicable to the SAP08P/N because a thin inner lead is used
for S terminal.)
IC
Transistor destruction point
C
Thick-film resistor
destruction point
B
A.S.O.
Curve
S
D
External
emitter resistor
E
Output terminal
VCE