LM311MX Equivalent & Substitute Parts

Part Overview

The LM311MX is a general-purpose voltage comparator manufactured by onsemi in 8-SOIC surface-mount packaging. This device features open-collector and open-emitter outputs suitable for interfacing with various logic families. The LM311MX is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain functional compatibility across supply voltage ranges, input offset specifications, and output characteristics while accommodating modern packaging and compliance standards.

Key Parameters

Parameter	LM311MX Specification
Manufacturer	onsemi
Package / Case	8-SOIC (0.154", 3.90mm Width)
Type	General Purpose Comparator
Number of Elements	1
Output Type	Open-Collector, Open-Emitter
Voltage - Supply, Single/Dual (±)	5V ~ 30V, ±2.5V ~ 15V
Voltage - Input Offset (Max)	7.5mV @ 15V
Current - Input Bias (Max)	0.25µA @ 15V
Current - Quiescent (Max)	7.5mA
Operating Temperature	0°C ~ 70°C
Mounting Type	Surface Mount
Product Status	Obsolete
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the LM311MX are grouped based on the following critical parameters that determine functional compatibility:

Primary Compatibility Criteria:

Package type: 8-SOIC surface-mount form factor
Output configuration: Open-collector or open-emitter capability
Supply voltage range: Minimum 5V ~ 30V single supply or ±2.5V ~ 15V dual supply
Input offset voltage: Maximum 7.5mV specification
Input bias current: Maximum 0.25µA specification
Quiescent current: Maximum 7.5mA specification

Grouping Logic:

Group 1 - Direct 8-SOIC Package Substitutes (Highest Compatibility): Parts maintaining identical 8-SOIC packaging with matching or superior electrical specifications. These include LM311DR2G (onsemi), LM311DR (Texas Instruments), LM311DT (STMicroelectronics), and LM211DT (STMicroelectronics). All support the required supply voltage range and output types.

Group 2 - Alternative Package Substitutes (Package Conversion Required): Parts with equivalent electrical performance but different packaging. AZV331KTR-E1 and AZV331KTR-G1 (Diodes Incorporated) use SOT-23-5 packaging with reduced supply voltage range (2.5V ~ 5.5V), suitable only for applications operating within this narrower range.

Group 3 - Enhanced Performance Substitutes (8-SO Package): LT1011IS8#PBF (Analog Devices Inc.) in 8-SO packaging offers superior input offset voltage (2mV), lower input bias current (0.065µA), and extended supply voltage range (3V ~ 36V, ±1.5V ~ 18V), with active product status and RoHS3 compliance.

Parameter Comparison

Part Number	Manufacturer	Package	Product Status	Supply Voltage (±)	Input Offset (Max)	Input Bias (Max)	Quiescent Current (Max)	Output Type	Operating Temp	RoHS Status
LM311MX	onsemi	8-SOIC	Obsolete	5V~30V, ±2.5V~15V	7.5mV @ 15V	0.25µA @ 15V	7.5mA	Open-Collector, Open-Emitter	0°C ~ 70°C	Not Specified
LM311DR2G	onsemi	8-SOIC	Active	5V~30V, ±2.5V~15V	7.5mV @ ±15V	0.25µA @ ±15V	7.5mA	DTL, MOS, Open-Collector, Open-Emitter, RTL, TTL	0°C ~ 70°C	ROHS3 Compliant
LM311DR	Texas Instruments	8-SOIC	Active	4.6V~30V, ±1.75V~15V	7.5mV @ ±15V	0.25µA @ ±15V	7.5mA	MOS, Open-Collector, Open-Emitter, TTL	0°C ~ 70°C	ROHS3 Compliant
LM311DT	STMicroelectronics	8-SOIC	Active	5V~30V, ±2.5V~15V	7.5mV @ ±15V	0.25µA @ ±15V	7.5mA	DTL, MOS, Open-Collector, Open-Emitter, RTL, TTL	0°C ~ 70°C	ROHS3 Compliant
LM211DT	STMicroelectronics	8-SOIC	Active	5V~30V, ±2.5V~15V	3mV @ ±15V	0.1µA @ ±15V	6mA	DTL, MOS, Open-Collector, Open-Emitter, RTL, TTL	-40°C ~ 105°C	ROHS3 Compliant
LT1011IS8#PBF	Analog Devices Inc.	8-SO	Active	3V~36V, ±1.5V~18V	2mV @ ±15V	0.065µA @ ±15V	4mA	Open-Collector	-40°C ~ 85°C	ROHS3 Compliant
AZV331KTR-E1	Diodes Incorporated	SOT-23-5	Active	2.5V~5.5V	7mV @ 5V	0.25µA @ 5V	120µA	Open-Collector	-40°C ~ 85°C	ROHS3 Compliant
AZV331KTR-G1	Diodes Incorporated	SOT-23-5	Active	2.5V~5.5V	7mV @ 5V	0.25µA @ 5V	120µA	Open-Collector	-40°C ~ 85°C	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (8-SOIC Package):

LM311DR2G (onsemi) provides the most direct substitution path. It maintains identical packaging, supply voltage specifications, and electrical characteristics while offering active product status and RoHS3 compliance. This part is recommended for designs requiring minimal qualification effort.

LM311DT (STMicroelectronics) and LM311DR (Texas Instruments) are functionally equivalent alternatives in 8-SOIC packaging. LM311DT matches the original supply voltage range exactly. LM311DR operates at slightly lower minimum supply voltage (4.6V vs. 5V single supply) but maintains compatibility with the ±2.5V ~ 15V dual supply range.

For Enhanced Performance:

LM211DT (STMicroelectronics) offers superior specifications with lower input offset voltage (3mV), reduced input bias current (0.1µA), and extended operating temperature range (-40°C ~ 105°C). It maintains 8-SOIC packaging and RoHS3 compliance, making it suitable for applications requiring tighter tolerances and wider temperature operation.

LT1011IS8#PBF (Analog Devices Inc.) provides the highest performance with 2mV input offset voltage, 0.065µA input bias current, and extended supply voltage range (3V ~ 36V, ±1.5V ~ 18V). The 8-SO package is mechanically compatible with 8-SOIC footprints. This part is recommended for precision applications and designs requiring extended supply voltage flexibility.

For Space-Constrained Applications:

AZV331KTR-E1 and AZV331KTR-G1 (Diodes Incorporated) in SOT-23-5 packaging reduce board area by approximately 60% compared to 8-SOIC. These parts are suitable only for applications operating within the 2.5V ~ 5.5V supply range. Higher quiescent current (120µA) should be evaluated for battery-powered designs.

Compliance Considerations:

All recommended active substitutes carry RoHS3 compliance certification. The LM311MX (obsolete) compliance status is not specified. Designs transitioning from LM311MX should prioritize RoHS3-compliant alternatives to ensure regulatory alignment and supply chain continuity.

Frequently Asked Questions (FAQ)

Q: Can LM311DR2G directly replace LM311MX without PCB modifications?

A: Yes. LM311DR2G maintains identical 8-SOIC packaging, pin configuration, and electrical specifications. No PCB layout changes are required. The part is pin-for-pin compatible.

Q: What is the key difference between LM311DT and LM311DR?

A: Both are functionally equivalent in 8-SOIC packaging. LM311DT (STMicroelectronics) matches the original 5V ~ 30V single supply range exactly. LM311DR (Texas Instruments) operates at 4.6V minimum single supply, providing slightly broader low-voltage compatibility while maintaining ±2.5V ~ 15V dual supply operation.

Q: Why do AZV331KTR-E1 and AZV331KTR-G1 have different MSL ratings despite identical electrical specifications?

A: Both parts are functionally identical. AZV331KTR-E1 carries MSL 1 (Unlimited moisture sensitivity), while AZV331KTR-G1 carries MSL 3 (168 Hours). MSL rating affects storage and handling requirements. Select based on your supply chain and storage conditions.

Q: Can I use LT1011IS8#PBF in place of LM311MX?

A: Yes, with package consideration. LT1011IS8#PBF uses 8-SO packaging instead of 8-SOIC, but both are mechanically compatible with standard 8-pin SOIC footprints. The part offers superior performance (2mV input offset vs. 7.5mV) and extended supply voltage range (3V ~ 36V vs. 5V ~ 30V). Verify footprint compatibility with your PCB design tools.

Q: Are AZV331KTR-E1 and AZV331KTR-G1 suitable for my 12V supply application?

A: No. Both AZV331 variants operate only within 2.5V ~ 5.5V supply range. They are not compatible with 12V supplies. Use LM311DR2G, LM311DT, LM311DR, or LM211DT for applications requiring higher supply voltages.

Q: What is the advantage of LM211DT over LM311DT?

A: LM211DT provides tighter input offset voltage specification (3mV vs. 7.5mV), lower input bias current (0.1µA vs. 0.25µA), lower quiescent current (6mA vs. 7.5mA), and extended operating temperature range (-40°C ~ 105°C vs. 0°C ~ 70°C). Select LM211DT for precision applications or designs requiring wider temperature operation.

Q: Is the LM311MX still available for purchase?

A: LM311MX is classified as obsolete. While 12,400 pieces are reported in inventory, new production is not available. Transition to active alternatives such as LM311DR2G, LM311DT, or LM311DR to ensure long-term supply chain security.

Q: Do all substitute parts carry RoHS3 compliance?

A: All active substitute parts listed carry RoHS3 compliance certification. The original LM311MX (obsolete) compliance status is not specified. Verify RoHS compliance requirements for your application and select accordingly.

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