VCC

V_CC is an abbreviation for "common-collector voltage". It most likely originated as the supply voltage for a common collector amplifier. It was then extended to become the pin on a TTL logic IC that similarly connected to all of the BJT collectors. V_EE refers to similar pins on devices with common-emitter connections. TTL logic usually uses BJTs, so uses the V_CC/V_EE labeling, while CMOS uses FETs and the V_DD (drain), and V_SS (source) labels. These distinctions have now been blurred, and newer chips often just use V_CC for the positive power connection, regardless of the type of transistors that make it up.

BJT	FET
VCC	VDD	Positive supply voltage
VEE	VSS	Negative supply voltage

External links

• Electrical Engineering Glossary Definition for Vcc
• Vcc, Vdd, Vss, etc.