I want to use a classic 555 timer IC to drive the base of a PNP transistor through a resistor, the emitter of the transistor being tied to the 555's Vcc. The 555 datasheet gives a graph for the high-state output voltage vs. sourcing current, but not when the load is tied to Vcc.
Vcc -------------------------- | | .|. | | | | | | | '-' | | | 555 out ___ | |< ------------|___|------| |\ | |
What I'm concerned about is: Is there a possibility that the high-state output of the 555 drops low enough below Vcc to partially turn on the PNP transistor? I could increase the turn-on threshold of the transistor with diodes, an LED or a resistive voltage divider, but I'd like to avoid that if it's not needed.