I need a circuit, simple, small, and cheap, that can switch on and off a 7.2 V power rail, controlled from a logic level (3.3V) digital signal. It needs to be very low leakage when the rail is off since it's in a low-power battery based system. The power rail is enabled for a small portion of the time (less than 1% duty) but may draw 300 mA or more during the several seconds of active operation. The first design was a two-resistor version (base resistor on the lower transistor and a resistor between lower collector and upper transistor's base). Later, I tried to reduce parts count by replacing the base resistor and collector resistor with a single emitter resistor. By my calculation, this creates a constant current sink through the top transistor' E-B junction when the logic signal enables the rail. I have a few questions: (1) Does this circuit look ok to you? Any possible problems? (2) Is there any reason to prefer either the two-resistor circuit or the single-resistor circuit in this application? (3) Is there a name for these particular transistor circuits? Note: LTspice files attached.