I have a pulse charging circuit where the maximum current is limited by the hFE of the PNP transistor (DTA144EE). The typical hFE at room temperature is ~220 as shown in the plot below. There is of course no spec on the max Hfe at room or any other temperature.
My calculations show that the circuit will correctly limit the current to 100 mA due to the current gain as long as the gain is not more than 500.
Is > 500 a physically realizable gain value at 100 mA for a low power discrete PNP transistor, or am I safe to assume that the gain will never be more than 500? Note that I am operating in fast pulse mode, so 100 mA is in the safe operating area for the ~100 ms charge time for the circuit.
Note that PNPs with 500 gain exist, but I could not find one near that at 100 mA of collector current. The high gain was in the 1 mA range.
Also, doesn't gain typically go down at higher currents?