LM3916 Dot/Bar Display Driver

29 October 2019 - 0 Comments

LM3916 Dot/Bar Display Driver

LM3916 Pinout

LM3916 is a monolithic integrated circuit that senses analog voltage level especially audio signals and drives 10 LED’s either in dot mode or in bargraph mode. This is a versatile IC. Multiple IC’s can be cascaded to drive more than 10 LED’s for higher resolution. The most popular application of the LM3916 is VU meter. The IC is available as DIP package from the manufacturers.

Pin Description:

PIN NO	PIN NAME	PIN DESCRIPTION
1, 10 to 18	LED Outputs	Connect LED’s negative leg to these pins.
2	V-	Connect this pin to ground.
3	V+	Connect this pin to positive supply.
4	R_LO	Low voltage reference pin.
5	SIG	Signal input to this pin.
6	R_HI	High voltage reference pin.
7	REF OUT	Internal voltage reference output pin.
8	REF ADJ	Internal voltage reference adjust pin.
9	MODE	Mode choosing pin for either Dot or Bar mode.

Features of LM3916:

Wide input voltage range: V_in = 3V to 25V.
Externally selectable dot or bar mode.
Programmable output current from 1mA to 30mA.
Directly drives TTL and CMOS loads.
Internal LED driver.

Note: More technical details can be found at the LM3916 datasheet linked at the bottom of this page.

Alternatives for LM3916: LM3914 and LM3915.

LM3916 Replacement: NTE1549.

How to use LM3916:

As said earlier, the LM3916 drives 10 LED’s with respect to analog input signal. The LED’s can be driven as either dot mode or bar mode by connecting to positive supply or left floating. The basic LM3916 circuit is given below.

Basic Circuit of LM3916 Dot/Bar Display Driver

The current through the LED and the reference voltage can be programmed using voltage divider resistors on pin 7 of the IC.

Basic Circuit of LM3916 Dot/Bar Display Driver

The value of the resistors can be calculated using the formula,

V_out = V_Ref(1+ R2R1) + I_AdjR2

Dot Mode and Bar Mode:

The mode pin can be used to drive the LEDs in either dot or bar mode. In dot mode, only one LED is lit at a time. In bar mode, The LED starts lit from the lowest led (starts from pin1) to the top LED according to the input signal. To use the IC in bar mode, connect the mode pin (pin 9) directly to pin 3 of LM3916. If the pin 9 open left, the IC is in dot mode.