文档介绍：AN-3004 APPLICATION NOTE
APPLICATION NOTE AN-3004
# REV. 5/7/02
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REV. 5/7/02
SEMIGONIDLJCTOR
AN-3004 APPLICATION NOTE
APPLICATION NOTE AN-3004
# REV. 5/7/02
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REV. 5/7/02
Application Note AN-3004
Applications of Zero Voltage Crossing Optically Isolated Triac Drivers
AN-3004 APPLICATION NOTE
APPLICATION NOTE AN-3004
# REV. 5/7/02
REV. 5/7/02 #

REV. 5/7/02
AN-3004 APPLICATION NOTE
APPLICATION NOTE AN-3004
2 REV. 5/7/02
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REV. 5/7/02
MT
DETECTOR
LED
Figure 1. Schematic of Zero Crossing Optically Isolated Triac Driver
In troductio n
The zero-cross family of optically isolated triac drivers is an in expe nsive, simple and effective soluti on for in terface applications between low current dc control circuits such as logic gates and microprocessors and ac power loads (120, 240 or 380 volt, sin gle or 3-phase).
These devices provide suf?cie nt gate trigger curre nt for high curre nt, high voltage thyristors, while provid ing a guara n- teed kV dielectric withstand voltage between the line and the control circultry. An integrated, zero-crossing switch on the detector chip elim in ates curre nt surges and the result ing electromag netic in terfere nee (EMI) and reliability problems for many applicati ons. The high tran sie nt immu nity of 5000 V/ 卩 s, combined with the features of low coupling capaci- tan ce, high isolati on resita nee and up to 800 volt speci?ed V drm ratings qualify this triac driver family as the ideal link between sensitive control circuitry and the ac power system en viro nment.
Optically isolated triac drivers are not inten ded for sta nd alone service as are such devices as solid state relays. They will, however, replace costly and space dema nding discrete drive circuitry ha