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LM111-N Voltage Comparator

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The LM111-N is a voltage comparator that has input currents nearly a thousand times lower than devices like the LM106 or LM710. LM111-N designed to operate over a wider range of supply voltages: from standard ±15V op-amp supplies down to the single 5V supply used for IC logic.


Pin Description of LM111-N

Pin Number

Pin Name




Ground pin


Non-Inverting Input (IN+)

The Non-Inverting Pin of the comparator gives a variable voltage to compare


Inverting Input (IN-)

The Inverting pin is also given a fixed voltage which is compared with the (IN+)


Ground (VCC-)

Ground pin connected to the case



This pin can be used to turn off the DC-offset voltage



This pin can be used to turn off the output stage



 Output Pin



Provide the operating voltage for the Op-Amp. For LT111 it is up to +15V


LM111-N Features and Specifications

  • Supply Voltage - Max:36 V
  • Supply Voltage - Min: 5 V
  • Operating Supply Current: 6 mA
  • Response Time: 200 ns
  • Input Offset Voltage: 3 mV
  • Input Bias Current: 100nA
  • Maximum Dual Supply Voltage: +/- 18 V
  • Minimum Dual Supply Voltage: +/- 2.5 V


Note: Complete technical details can be found in the LM111-N datasheet given at the end of this page.


Equivalent for LM111-N: LM211-N, LM311-N

Alternatives Comparator Op-Amp IC: LM741, LM358, LM339, LM324


Where to use the LM111-N Comparator Op-Amp

The LM111-N Voltage Comparator Op-Amp is a very popular comparator IC from Texas Instruments that is used for Voltage comparisons in electronic designs. Unlike the LM111, LM111-N doesn’t have an output transistor inside it.


This transistor can drive lamps or relays, switching voltages up to 50V and 50mA and its output is compatible with RTL, DTL, and TTL as well as MOS circuits. So if you are looking for a high-speed comparator with fast input signals and low source impedances, then LM111-N might be the right choice for you.


How to Use LM111-N

A typical voltage comparator compares a signal to a reference or two signals against each other. Like all voltage Comparators, the LM111-N also has an Inverting Pin and a Non-Inverting Pin. If the voltage at the Non-Inverting Terminal (pin 2) is high than the Inverting Terminal (pin 2), the output (pin 7) will also be high else the output will be low. A simple application circuit from LM111 datasheet is given below:

LM111N Application Circuit

The given circuit is a zero-crossing detector circuit. Output current is determined by the pull-up resistance and pullup voltage. The trim pins (pins 5 and 6) act as unwanted auxiliary inputs. If these pins are not connected to a trim-pot, they should be shorted together.


Applications of LM111-N

  • Voltage Comparator circuits
  • Can drive Relay, Lamp, Motor, Etc.
  • Zero-Crossing detector
  • Peak voltage Detector
  • High Voltage protection/Warning
  • Oscillator circuits


2D-Model of LM111-N

Dimensions for LM111 is given below. These dimensions are for the SOIC package.

LM111N Dimensions

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