The LM3916 is a monolithic integrated circuit used as a dot/bar display driver. It specializes in sensing various levels of analog voltages to operate ten LEDs, LCDs or vacuum fluorescent displays. The current flowing through these LEDs is so programmable and regulated that it bypasses the use of current limiting resistors in series with LEDs. It requires a single power supply to make this dot driver display operational. This voltage ranges from a low value of 3V to high as 25V. The voltage reference used in IC is easily adjustable.
Where to use LM3916 Dot/Bar Display Driver
If it is intended to change the display from the bar graph to move the dot, one pin is there to serve the purpose which is quite simple and easily interpretable. The voltage divider inside LM3916 dot display driver is designed for 10 steps which actually corresponds to 10 LEDs or LCDs displays. The input signals from 0-1.5V of positive DC are made acceptable by the use of high impedance input buffer. This buffer makes 10 comparators operational with an overall accuracy of more than 0.2 dB.
For a full-scale 1.2V meter, only one resistor is needed in addition to ten LEDs. The mere use of an additional resistor makes it independent of supply voltage for operation from 1.2V to 12V. LM 3916 can withstand voltages between ±35V. A single pot adjusts the brightness of LEDs. It is therefore the electronic form of the well-known VU meter.
Pinout Diagram LM3916 Bar Display Driver
The dual inline package of LM 3916 is available as 18 pin IC. The pinouts diagram is shown here:
|Pin Number||PINS Name||Details|
|1||( LED No. 01)||This pin is for connecting LED|
|2||( Negative Supply Voltage )||This pin for applying the negative supply voltage|
|3||(Positive Supply Voltage)||This pin is for applying positive supply voltage|
|4||(Divider-Lower End)||This pin is indication of zero/ lower end of divider inside IC|
|5||(Signal Input)||This pin is for applying input signal|
|6||(Divider-High End)||This pin is indication of higher/ maximum end of divider inside IC|
|7||(Reference Output)||This pin is for having the output reference|
|8||(Reference Adjust)||This pin is for adjustment of reference|
|9||(Mode Select)||This pin helps changes in mode|
|10||(LED No. 10)||This pin is for connecting LED|
|11||(LED N0. 09)||This pin is for connecting LED|
|12||(LED N0. 08)||This pin is for connecting LED|
|13||(LED N0. 07)||This pin is for connecting LED|
|14||(LED N0. 06)||This pin is for connecting LED|
|15||(LED N0. 05)||This pin is for connecting LED|
|16||(LED N0. 04)||This pin is for connecting LED|
|17||(LED N0. 03)||This pin is for connecting LED|
|18||(LED N0. 02)||This pin is for connecting LED|
The operational features of the LM3916 display driver are listed in this table as per datasheet:
|Offset Voltage, Buffer and First Comparator (mV)||10|
|Offset Voltage, Buffer and Any Other Comparator (mV)||15|
|Input bias current (nA) (at pin5)||100|
|Input Signal Over Voltage (V)||±35|
|Divider Resistance (total pin 6-4)||8-17 kΩ|
|Output Voltage (V)||1.34|
|Line Regulation (%/V)||0.03|
|Load Regulation (%)||2|
|Adjust Pin Current (µA)||120|
|LED Current (mA)||13|
|LED Current Difference (mA)||0.4-3.0|
|LED Current Regulation (mA)||0.25-3.0|
|Drop Out Voltage (V)||1.5|
|Saturation Voltage (V)||0.4|
|Output Leakage Each Collector-Bar Mode (µA)||100|
|Output Leakage –Dot Mode Pin 10-18 (µA)||100|
|Output Leakage –Dot Mode Pin 01 (µA)||450|
|Stand By Supply Current (mA)||9.2|
Where and How to Use LM3916?
A simplified block diagram circuit of the LM3916 LED bar driver is shown to depict the operation of this IC.
The LEDs are connected to pin no. 1 and pins 10-18 as shown above. The higher end of the divider i.e. pin no. 6 is connected to an external resistor and reference adjustment at pin 8. The lower end of divider i.e. pin no. 4 is grounded. The current flowing out of the pin no. 7 determines the brightness of LEDs. The current flowing through each LED while glowing is around ten times greater than the current flowing out of the reference out pin no 7. An internal voltage reference of 1.25V is applied to the string of resistors. As the input voltage changes from 0-1.25V, the output of comparators is set to low one by one thus turning on the LEDs.
The input signal ranging from 0-12V is applied pin no. 5 as an input to the high input impedance buffer. The mode pin i.e. pins no. 9 selects mode as bar graph or dot display. For bar graph display pin no. 9 is directly connected to pin no. 3 while pin no. 9 is kept open circuited for selecting dot display.
DOT OR BAR MODE SELECTION
Pin number 9 is a mode selection pin that is used to select either dot mode or bar mode. Make connections according to these criteria to select either mode.
- Bar Graph Display: Wire Mode Select (pin 9) directly to pin 3 (V+ pin).
- Dot Display, Single LM3916 Driver: Leave the Mode Select pin open circuit.
Examples of LM3916
LM3916 can be used for the construction of:
- Half wave peak detector
- Precision full wave average detector
- Precision full wave peak detector
- Driving vacuum florescent display
- High-resolution VU meter
- LCD driver
- Bar display with alarm flasher
- Precision half wave rectifier
The real-life applications of LM 3916 are:
- Audio visualization circuits
- Battery level indicators
- Low cost display / monitor devices
- Digital gauges
- Electronic displays
- Fade bars
- LED flashers
- Advertisement boards
- Traffic lights and display bars
- Water level visual indicators
2D Diagram of dot display driver IC