What exactly are the main voltage standards called for all the common voltages we see? 3.3V, 5V and 12V are some of the most common DC voltages but what are they known as exactly and what's with their significance? i.e. Were they picked as it sounded like a nice value or for an electronically significant reason?
Answer
3.3 volts was chosen as a JEDEC standard. Electronics had moved on from the the old 5V (TTL) and 4000 series CMOS (3 - 15V).
Technology changed and industry moved toward a lower voltage:
e.g. Transistors got smaller, so the threshold voltage is lowered, a need for faster circuits, lowering the voltage will reduce the time it takes to change logic levels, TTL logic is being phased out, less demand for 5V compatibility higher packaging density so power usage is a concern and so on.
As a world wide industry agreed standards are important to ensure product compatibility.
The 12V probably comes from the use of battery power - most cars using a '12V' lead acid accumulator. Trucks tends to use 24V and aviation has its own standards. As far as I am aware 12V was never an electronics standard, it was simply in common use as was (is) 9V.
No comments:
Post a Comment