One pin changes the display from a bar graph to a moving dot display. LED current drive is regulated and programmable, eliminating the need for current limiting re- sistors. The whole display system can operate from a single supply as low as 3V or as high as 25V. The IC contains an adjustable voltage reference and an accurate ten-step voltage divider. The high-impedance input buffer accepts signals down to ground and up to within 1. The input buffer drives 10 individual com- parators referenced to the precision divider.
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Where to use LM? This IC eliminates the need for microcontroller and programming and also reduces the hardware required to control 10 LEDs. The analog input voltage can vary from 3V to 18V and the LED current can be limited by simply using a single resistor on pin 7 Ref Out. How to use a LM? The advantage of using LM is that it requires minimum hardware and can be easily set up. We simply have to connect the 10 LEDs to the IC, set the reference voltages for input voltage and limit the current through the LED and we are all set.
The below circuit is a typical application circuit for LM Here we have used 9V to power the IC to monitor an analogy voltage of V. Always note that the voltage used to power the IC here 9V should be at least 1.
Since we are monitoring V here, the low reference voltage pin 4 is set at 0V and the high reference voltage pin 6 is set to 5V. As you might have noticed we have connected all the 10 LEDs directly to the IC without any current limiting resistor this is because the IC has an internal current limiter and the value of current can be set by using the pin VRO pin 7.
The formulae to calculate the current is given below, where I is the current through each LED and RL is the resistor connected to pin 7.
This is because the IC output pins can only sink current and cannot source it. The IC can operate in two different modes, one is the dot mode and the other is bar mode. In dot mode the mode pin pin 9 has to be left floating, in this mode only one LED will be turned on based on the input voltage.
Both the modes are shown in the gif file above.
LM3916 Datasheet PDF - Texas Instruments
LM3916 Dot/Bar Display Driver Pinout and Examples
View lm3916 datasheet: