IC LM3914 : Pin Configuration,Working and Applications

LM3914 is an analog controlled LED driver IC, launched by the national semiconductor in 1980. It can control 10 LED lights based on an analog input voltage. It is best to alternate microcontroller ic where 10 LEDs have to control so it reduces the hardware.

IC LM3914 can control 3V to 18V and the current for LED can be limited by simply using a single resistor on pin 7. This IC also has two operating modes BAR mode and DOT mode. You can also use more than one IC to control up to 100 LEDs. By using this IC the LEDs can be controlled without any flickering and flawlessly with equal brightness.  Due to these good features this IC commonly used in visual alarms and other monitoring applications.  In short, if you are looking for an IC to driver your bar LED lights then this IC might be of interest to you.

LM3914 IC: Pin Configuration, Circuit Working and Applications

LM3914 IC Pin Configuration

  • Pin1: (LED1, LED2, LED3,..LED10): These pins are allied to LEDs.

  • Pin2: (Ground or V-): GND pin of the LM3914 IC

  • Pin3: (Vcc or V+): DC voltage from 3V to 18V as supply

  • Pin4: (RLO): Low-level voltage used for potential divider

  • Pin5: (Signal): Analog signal input based on which the LED is controlled.

  • Pin6: (RHI): High-level voltage for potential divider

  • Pin7: (Ref Out): Reference voltage of Output

  • Pin8: (Ref Adj): Adjust pin

  • Pin9: (Mode): Choose among Bar or Dot mode

Specifications

  • Its is Analog Controlled LED Driver IC
  •  Controllable for LEDs: 10
  • 3V to 18V Operating Voltage:
  • Analog Input voltage range: 1.2V to 12V
  • LED sink current: 2mA to 30mA
  • Both Bar/Dot mode available
  • More IC can be used to control up to 100 LEDs
  • Available in 18-pin DIP

Alternative LED Driver IC

CD4511, MAX7219, and CD4054 can be used as an alternate of LM3914

Battery Charge Indicator Circuit Design using LM3914

battery level indicator

In this circuit D1 to D10 LEDs displays the capacity of the battery dot bar display can also be used for indication instead of LEDs. External switch sw1 is used to select the mode, sw1 is connected to the 9th pin of LM39-14-IC. The 6th and 7th pins are connected to the ground through a (R1) resistor. This resistor controls the brightness of LEDs. Resistor R3 and RV1 are formed a potential divider circuit. Here RV1 is used for calibration. There is no need for an external power supply to operate this circuit.

The circuit is designed to monitor the current 10V to 15V DC.  The operating voltage of this IC-LM3914 is 3v to 25v DC, so this circuit will work even on 3v. The IC-LM3914 contains adjustable reference and accurate 10-steps divider. This IC-LM3914 can also act as a sequencer.

Battery Level Indicator

Applications of LM3914 IC

Some applications of electronics base on LM3914 are given below.

  • Battery current level indicator
  • 12V Car Battery monitoring
  • Tester Circuit for Soil Moisture
  • Lead Acid Battery Charger monitor
  • Automatic Charge Monitoring Circuit
  • Automatic temperature controller
  • Temperature meter circuit
  • Electronics Digital and analog gauges
  • Electronic displays
  • Low-cost monitor electronics projects

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