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IC power-supply pin
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<p> IC power-supply pins are voltage and current supply terminals found on <a href="/facts/Integrated_circuits/fjn6vg7C">integrated circuits</a> (ICs) in <a href="/facts/Electrical_engineering/YYXW1KLW">electrical engineering</a>, <a href="/facts/Electronic_engineering/WCSVulpu">electronic engineering</a>, and <a href="/facts/Integrated_circuit_design/sE0qVzyo">integrated circuit design</a>. ICs have at least two pins that connect to the <a href="/facts/Power_supply_rail/3nvssXFG">power rails</a> of the circuit in which they are installed. These are known as the power-supply pins. However, the labeling of the pins varies by IC family and manufacturer. The double-subscript notation usually corresponds to a first letter in a given IC family (transistors) notation of the terminals (e.g. VDD supply for a drain terminal in FETs etc.). </p> Typical supply-pin labeling<table><tbody><tr><th></th><th><a href="/facts/Bipolar_junction_transistor/9BMcGv5Q">NPN BJT</a></th><th><a href="/facts/Field_effect_transistor/TerYC6Nz">N-FET</a></th><th></th><th></th><th>AC/DC</th><th>DC</th><th>DC</th></tr><tr><td>Positive supply voltage</td><td>VCC/VBB</td><td>VDD</td><td>V+</td><td>VS+</td><td>VIN</td><td>VDD</td><td>VA</td></tr><tr><td>Negative supply voltage</td><td>VEE</td><td>VSS</td><td>V−</td><td>VS−</td><td></td><td></td><td></td></tr><tr><td>Ground</td><td>GND</td><td>GND</td><td>0</td><td>0</td><td>GND</td><td>GND</td><td>GND</td></tr></tbody></table> <p>The simplest labels are V+ and V−, but internal design and historical traditions have led to a variety of other labels being used. V+ and V− may also refer to the non-inverting (+) and inverting (−) voltage inputs of ICs like <a href="/facts/Op_amp/hunKdYb9">op amps</a>. </p><p>For power supplies, sometimes one of the supply rails is referred to as <a href="/facts/Ground_(electricity)/F6TEMIVv">ground</a> (abbreviated "GND") – positive and negative voltages are relative to the ground. In digital electronics, negative voltages are seldom present, and the ground nearly always is the lowest voltage level. In analog electronics (e.g. an <a href="/facts/Audio_power_amplifier/NqLdbyS2">audio power amplifier</a>) the ground can be a voltage level between the most positive and most negative voltage level. </p><p>While <a href="/facts/Double-subscript_notation/ua3brLKw">double-subscript notation</a>, where subscripted letters denote the difference between two points, uses similar-looking placeholders with subscripts, the double-letter supply voltage subscript notation is not directly linked (though it may have been an influencing factor). </p>