Each man carried away electronics is facing foreign origin materials. And whether it is an electronic device or circuit specification to chip, there may occur a number of different designations food chains, which may well confuse the novice or unfamiliar with the topic amateur radio. On the Internet, sufficient information to clarify this question. Next, summarized what was found on the designations of origin and their application.
VCC, VOF, VDD, VSS – where such designations? Designations supply circuits stem from the analysis transistorized circuits, Where, usually, treated with a transistor circuit and the resistors connected thereto. Voltage (relative to ground) the collector (collector), emittere (emitter) and base (base) denoted VC, VE and VB. Resistors connected to the terminals of the transistor is denoted RC, RE and RB. The voltage at the farthest (from the transistor) terminal of the resistor is often denoted VCC, VOF and VBB. On practice, for example NPN transistor included in the circuit with a common emitter, VCC correspond to the positive side, and VOF minus power source. Accordingly, for the PNP transistor will conversely.
Similar arguments for FETs and N-type common-source circuits give explanation notation VDD and VSS (D — drain, drain; S — source, east): VDD — a plus, VSS — minus.
Designations voltages at the terminals of vacuum tubes may be as follows: VP (plate, anode), VK (cathode, namely K, not C), VG (grid, grid).
As described above, Vcc and Vee are used for circuits using bipolar transistors (VCC – a plus, VOF - minus), and Vdd and Vss to FET circuits (VDD – a plus, VSS — minus). This designation is not correct, because chips are composed of complementary pairs of transistors. for example, CMOS chips have, plus is connected to the P-FET roots, and negative to the N-FET roots. However, This notation for conventional resist supply circuits regardless of the conductivity type of transistors used.
For circuits with two polar power VCC and VDD can interpreted as the largest positive, and VOF and VSS as the most negative voltage in the circuit with respect to ground.
For chips fed from one or several sources of the same polarity minus often denoted GND (land). The land may be different, For example, warning, compound with housing, grounding.
Here is a list of some symbols (far from complete).
|GND||Land (minus power)||Ground|
|AGND||analog ground (minus power)||Analog ground|
|DGND||Digital ground (plus power)||Digital ground|
(most positive voltage)
|Land, minus power
(the most negative voltage)
|Vref||The reference voltage
(ADC, CAP, comparators and others.)
|Reference (reference, sample)|
|Vpp||Voltage programming / erasing||(may pp = programming power)|
(For example, in PLIS)
VCCIOSupply voltage peripheral circuits
(For example, in PLIS)Input/Output (input Output)
As seen, often refer formed by adding the words, one or more letters (possible numbers), that correspond to the letters in the word chain reflecting function (For example, how Vref).
Sometimes Vcc and Vdd designations may be present in a single chip (or device), then it can be, For example, voltage transformer. It may also be a sign of dual power. In this case, usually, Vcc power corresponds nutrition or peripheral portion, Vdd supply pin (usually Vcc>=Vdd), and negative power supply can be labeled Vss.
Combining modern chips of different technologies, traditions, or any other reason, led to, that there is no clear criteria for selecting a particular designation. Therefore, there is, that the designation "mixed", For example, using VCC with VSS or VDD with VOF, but the meaning of, usually, stored - VCC > VSS, VDD > VOF. for example, almost everywhere, It can be found in the specifications for the 74HC series chips (HC = High speed CMOS), 74LVC et al., Food as a symbol Vcc. ie. at the specifications of CMOS (CMOS) chip used for identification circuits using bipolar transistors.
The texts of any standard (ANSI, IEEE) could not be found on this subject. That is why the text contains the word "maybe", "sometimes", "Usually" and similar. In spite of this, The given information is sufficient, to slightly better navigate the foreign materials in electronics.