ZENER DIODE PROTECTION NETWORK IN SUBMOUNT FOR LEDS CONNECTED IN SERIES

摘要

A transient voltage suppressor circuit is disclosed for a plurality (N) of LEDs connected in series. Only one zener diode is created for connection to each node between LEDs, and a pair of zener diodes (the “end” zener diodes) are connected to the two pins (anode and cathode pads) of the series string. Therefore, only N+1 zener diodes are used. The end zener diodes (Q1 and Qn+1) effectively create back-to-back zener diodes across the two pins since the zener diodes share a common p+ substrate. The n+ regions of the end zener diodes Q1 and Qn+1 have the highest breakdown voltage requirement and must be placed relatively far apart. Adjacent n+ regions of the intermediate zener diodes have a much lower breakdown voltage requirement so may be located close together. Since there are fewer zener diodes and their spacings may be small, the zener diodes may be placed within a very small footprint or can be larger for better suppressor performance.