In Fairchild's MMBT4401's datasheet (Note: This is not the newest one from official site, but it seems it contain more information than the newest one, so I use it as an alternative), there are some parameter tables and diagrams relative to "switching characteristics".
All them are tested under certain conditions, such as Vcc = 30V, Ic = 150mA, etc. I wonder how can I use them to get the parameters in my own circuit configurations, such as Vcc = 5V, Ic = xx mA. Is there some simple math equations, or estimations to get them from the given ones at given conditions?
Best Answer
On occasions like this I would immediately turn to LTSpice or whatever spice simulation software was available and look how fast it is going to operate under the supply and load conditions you have. The formulas and equations held/implied within the spice models will be more accurate at predicting real life than "simple math equations".
If you feel that a simulator is too big a step, I'd still encourage you to go down that path because they help me to solve a lot of engineering problems and give great results. For what you want here, they would give +95% accurate values I reckon.