Vcc

Vcc

An electronics designation that refers to voltage from a power supply connected to the "collector" terminal of a bipolar transistor. In an NPN bipolar (BJT) transistor, it would be +V_cc, while in a PNP transistor, it would be -V_cc.

Double letters (cc) refer to power supply voltages. For example, V_ee refers to the "emitter" voltage. In CMOS logic, V_ss refers to the "source" voltage, and V_dd is the "drain" voltage.

Single letters refer to the voltage relative to ground; for example, V_c is the "collector" voltage relative to ground. Two different letters indicate the voltage between two terminals; for example: V_be is the "base" to "emitter" voltage drop, while V_ce is the "collector" to "emitter" voltage.