Minggu, 15 Juli 2012

Function zener

Of the myriad components available to electronic designers, zener diodes are among the handiest and strangest. Similar to normal semiconductor diodes in most respects, they also regulate voltage and are designed to work backwards. Their reliability, low cost and small size make them a good choice when a circuit needs constant voltage. Function zener A zener is a kind of semiconductor diode. As with other diodes, it prefers to conduct current in one direction. Normal diodes have a reverse breakdown voltage; no current will flow opposite to the preferred direction, but if the voltage is more than the breakdown value, current will flow and damage the part. A zener, on the other hand, won't be damaged as long as the current is under the device's limit. Used this way, the voltage across the zener will be a constant value determined by the diode itself. They are commonly available in the range of 1.8 to 200 volts. Identification Being a diode, a zener is a small part with two leads and usually a band on the body indicating polarity. The body may be glass, plastic, or metal. It's hard to tell zeners apart from other diodes, however. The best way of telling is by having the schematic handy, or looking up the part number. Considerations Zeners, like other diodes, can conduct only a limited amount of current. Too much current will cause the diode to short out, which could immediately destroy it. This means they're used in low-current parts of a circuit, such as a voltage reference that controls higher-current-carrying transistors. Expert Insight Being semiconductor diodes, zeners are temperature-sensitive. If it's an issue, good circuit design can compensate for this. Because of competing internal effects that cancel each other out, a 5.6V zener is much less sensitive to temperature than ones with lower or higher voltage ratings. Benefits Some devices, like flashlights, portable radios and toy cars, work fine for a range of voltages. Many electronic circuits, however, need a constant voltage somewhere in the design. Zeners are an easy-to-use, low-cost way of achieving good voltage regulation.

Tidak ada komentar:

Posting Komentar