We now scan for max of Ic, Ib, power, taking into
account the max allowed temperature, using the thermal
resistance rth0 model parameter between juntion and ambient.
Two user options are there: If rth0 is given, we calculate
a derating of the max power allowed.
Without a constant max power according to model param pow_max
is assumed.
The new model parameters for the bipolar model are:
pow_max, ic_max, ib_max, te_max, and rth0, in addition
to the already existing vbe_max, vbc_max, adn vce_max.