10_LED_BAR_GRAPH_INDICATOR_CIRCUIT

Published:2009/7/13 4:43:00 Author:May | From:SeekIC

The solid-state level indicator consists of a string of 10 LEDs in one package. With a low-level signal input, all LEDs are off. As the signal increases, more LEDs light up, until finally all10 are turned on to indicate the maximum level. The heart of the circuit shown in this figure is the National Semiconductor LM3915. The LM3915 contains a precision voltage reference, resistor divider chain, and 10 comparators to drive the LEDs. This IC also contains current-limiting circuitry that limits the brightness of the LEDs without the need for separate resistors, and logic to select either a bar graph or a moving-dot display.



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