| 摘要 |
A voltage regulator circuit for use in a current regulator circuit comprises a plurality of zener diodes Z11-n connected in parallel. The voltage regulator can provide a regulated voltage to a current driver of a current regulator comprising resistor R1 and transistor T1. The output of a first such regulator circuit can be cross-coupled to a similar second regulator comprising resistor R2, transistor T2 and parallel zener diodes Z21-n . The output of such a regulator can be connected to a resistive summing circuit (fig 7 RSC) which can be plural resistors connected in parallel. The current regulator can form a two-terminal circuit providing current IT, and be programmed by resistors R1 and/or R2. The zener diodes can be silicon diodes having a zener voltage of less than 5.5V and a variation of between 01. And 0.3 V between diodes and be selected so that they operate at a total current where the rate of change of zener voltage with temperature equals the rate of change of the base-emitter voltage of the transistor with temperature. The transistors can be bipolar silicon NPN or PNP types and form a complementary pair. The current regulator can be used to drive one or more LEDs and provides a temperature coefficient of current of substantially zero. . |
