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Oct 16 2020

LM311: A Detailed Introduction to Voltage Comparator

Introduction

The LM311 is a single comparator. In other words, it is internally composed of one comparator.

The LM311 compares these voltage inputs and determines which value is larger. On this basis, you can make electronic decisions based on which input is larger and which is smaller. Therefore, comparators are very useful in circuits where we measure the level and want our circuit to operate in a particular way, depending on whether the input level is above or below a certain threshold.


LM311 Images are for reference only.

LM311 - Differential Comparator IC


Catalog

Introduction

Document and Media

LM311 Pin Configuration and Functions

Basic Parameters

Features

Application

ECCN UNSPSC

Package and Pins

Functional Block Diagram

Where to Use LM311 

Product Manufacturer

Product Range

Alternative Models

FAQ


Document and Media

Component Datasheets       LM111,211,311

LM311 Pin Configuration and Functions

Let's take a closer look at the 8 pins of the LM311 comparator IC to understand what each pin means and what each pin does.

Pin Configuration

 

Pin Function


Basic Parameters

Amplifier Type

COMPARATOR

Approx. price (US$)

1ku | 0.06

Average Bias Current-Max (IIB)

0.25 µA

Brand Name

Texas Instruments

ECCN Code

EAR99

Factory Lead Time

1 Week

Features

Strobe, Vos Adj Pin

HTS Code

8542.39.00.01

Input Bias Current (+/-) (Max)

250 nA

Input Offset Voltage-Max

10000 µV

JESD-30 Code

R-PDSO-G8

JESD-609 Code

e4

Length

4.9 mm

Manufacturer

Texas Instruments

Manufacturer Part Number

LM311D

Moisture Sensitivity Level

1

Neg Supply Voltage Limit-Max

-18 V

Neg Supply Voltage-Nom

-15 V

Number of Channels

1

Number of Functions

1

Number of Terminals

8

Operating Temperature-Max

70 °C

Output Type

OPEN-COLLECTOR/OPEN-EMITTER

Package Body Material

PLASTIC/EPOXY

Package Description

SOP, SOP8,.25

Package Shape

RECTANGULAR

Package Style

SMALL OUTLINE

Packing Method

TUBE

Part Life Cycle Code

Active

Part Package Code

SOIC

Pbfree Code

Yes

Peak Reflow Temperature

260 ℃

Pin Count

8

Power Supplies

+-15 V

Propagation Delay Time

0.115 µs

Qualification Status

Not Qualified

Rail to Rail

No

Rating

Catalog

Reach Compliance Code

Compliant

Response Time-Nom

115 ns

Risk Rank

0.66

Rohs Code

Yes

Seated Height-Max

1.75 mm

Subcategory

Comparator

Supply Current-Max

7.5 mA

Supply Voltage Limit-Max

18 V

Supply Voltage-Nom

15 V

Surface Mount

YES

Technology

BIPOLAR

Temperature Grade

COMMERCIAL

Terminal Finish

Nickel/Palladium/Gold (Ni/Pd/Au)

Terminal Form

GULL WING

Terminal Pitch

1.27 mm

Terminal Position

DUAL

Time@Peak Reflow Temperature-Max

NOT SPECIFIED

VICR (Max)

28 V

VICR (Min)

0.5 V

Vos (offset voltage @ 25 C) (Max)

7.5 mV

Vs (Max)

30 V

Vs (Min)

3.5 V

Width

3.9 mm


Features

  • Fast Response Time: 165 ns
  • Strobe Capability
  • Maximum Input Bias Current: 300 nA
  • Maximum Input Offset Current: 70 nA
  • Can Operate From Single 5-V Supply
  • Available in Q-Temp Automotive

– High-Reliability Automotive Applications

– Configuration Control and Print Support

– Qualification to Automotive Standards

  • On Products Compliant to MIL-PRF-38535, All Parameters Are Tested Unless Otherwise Noted. On All Other Products, Production Processing Does Not Necessarily Include Testing of All Parameters.

Application

A typical LM311 application compares a single signal to a reference or two signals against each other. Many users take advantage of the open-drain output to drive the comparison logic output to a logic voltage level to an MCU or logic device. The wide supply range and high voltage capability makes LM311 optimal for level shifting to a higher or lower voltage.

The common applications of LM311 are mainly as follows:

  • Desktop PCs
  • Building Automation
  • Body Control Modules
  • Oscillators
  • White Goods
  • Peak Detectors

ECCN UNSPSC

Description

Value

ECCN Code

EAR99

HTS Code

8542.39.00.01


Package and Pins

Pakage Pins Size
PDIP (P) 8 93 mm²  9.81 x 9.43
SOIC (D) 8 19 mm²  3.91 x 4.9
SOIC (D) 8 19 mm²  4.9 x 3.9
SOP (PS) 8 48 mm²  6.2 x 7.8
TSSOP (PW) 8 19 mm²  3 x 6.4

Functional Block Diagram


Where to Use LM311 

The lm311 differential comparison operational amplifier is a very old Ti comparison IC which has been used in voltage comparison with electronic design for a long time. Any operational amplifier can be used as a voltage comparator, but lm311 proves its advantage by placing an output transistor in its package. The collector and emitter pins of the transistor can also be controlled by hardware, which makes it suitable for many applications.

The transistor can drive loads up to 50V and 50mA, and is suitable for driving most TTL, MOS and RTL loads. Transistors also insulate the load from the system ground, so if you are looking for a voltage comparator to drive these specifications of the load, the IC may be the right choice for you.


Product Manufacturer

Texas Instruments Inc. (TI) is an American technology company that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globally. Its headquarters are in Dallas, Texas, United States. TI is one of the top ten semiconductor companies worldwide, based on sales volume. Texas Instruments's focus is on developing analog chips and embedded processors, which accounts for more than 80% of their revenue. TI also produces TI digital light processing (DLP) technology and education technology products including calculators, microcontrollers and multi-core processors. To date, TI has more than 43,000 patents worldwide.


Product Range

Devices

Boards

Developer Tools

ARM ® PROCESSORS

AUTOMOTIVE PRODUCTS

IDENTIFICATION & SECURITY

Kinetis Cortex®-M Microcontrollers

In-Vehicle Network

NFC

LPC Cortex-M Microcontrollers

Microcontrollers and Processors

RFID


Alternative Models

901523-04,CA211,CA311,CA311S,CA311T,ECG922,LM211H,LM311,LM311H,LM311T,MLM111AG,MLM211AG,NTE922,SK3567,SK3567A,TCG922, UA311HC


FAQ

  • How to use LM311?

LM311 is a single-channel comparator. When using it, connect the reference voltage and the compared signal voltage to its non-inverting and inverting input terminals (pin 2 and pin 3), and its output is the result of the comparison. If you want the foward output result, pin 7 is connected to the positive power supply and pin 1 is the output. If the result is to be output in reverse, pin 1 is grounded and pin 7 is the open collector output.

  • lm311 and lm393 are both voltage comparators, so what is the difference between them?

LM311 is single voltage comparaotor, LM393 is dual voltage copatpr. LM311 has a load current of up to 50MA and a voltage of 40V. It can drive relays with a minimum power supply voltage of 5V.

The LM393 load current is 16MA, and the minimum voltage is 2V for a single power supply.

  • Whats the difference between LM311 and LM111?

Their functions are the same, and the 1XX series can be used in harsher environments.

The 3XX series can only be used in a commercial environment, typically the applicable temperature range of the device.

The price of 1xx is much more expensive than 3xx.

  • What does the 5 and 6-pin balance strobes of LM311 mean?

The function of balancing the mirror current of the reverse circuit is realized by connecting a potentiometer in the middle. In addition to the balance function, the 6 pin also has a strobe function, and the 6 pin can be grounded through the transistor drive circuit for strobe output.

  • What is the difference between lm311 voltage comparator dual power supply and single power supply?

The comparators are all open-collector outputs, without load resistance, they cannot output voltage signals.

Dual power supplies can detect signals lower than 0, and single power supplies can only detect signals higher than 0.

  • Can the lm311 comparator be powered by a positive and negative five-volt dual power supply?

Of course, LM311 can be powered by ±5V dual power supply. Its requirement for working power supply is that the voltage difference between the positive and negative power supply (or single power supply voltage) is at least 3.5V and the maximum is 30V, as long as it is within this range.

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