LM324WDT Equivalent & Substitute Parts

Part Overview

The LM324WDT is a general-purpose operational amplifier integrated circuit manufactured by Rohm Semiconductor, configured as a 4-circuit device in a 14-SOIC surface-mount package. This component is classified as obsolete, indicating discontinued production and limited availability through standard distribution channels. The identification of equivalent and substitute parts is necessary to maintain design continuity, ensure project completion, and provide alternative sourcing options for applications currently utilizing the LM324WDT.

Key Parameters

Parameter	Value
Amplifier Type	General Purpose
Number of Circuits	4
Package / Case	14-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Slew Rate	0.3 V/µs
Gain Bandwidth Product	800 kHz
Current - Input Bias	20 nA
Voltage - Input Offset	1 mV
Current - Supply	1 mA
Current - Output / Channel	30 mA
Voltage - Supply Span (Min)	3 V
Voltage - Supply Span (Max)	32 V
Operating Temperature	-40°C ~ 85°C
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the LM324WDT is determined by strict alignment of the following critical parameters:

Primary Substitution Criteria:

Amplifier Type: General Purpose
Number of Circuits: 4
Package / Case: 14-SOIC (0.154", 3.90mm Width)
Mounting Type: Surface Mount
Current - Input Bias: 20 nA
Voltage - Supply Span (Min): 3 V
Voltage - Supply Span (Max): ≥ 32 V

Secondary Compatibility Parameters:

Operating Temperature Range: Must encompass or exceed -40°C ~ 85°C
Current - Output / Channel: ≥ 30 mA
Voltage - Input Offset: ≤ 3 mV
RoHS3 Compliance: Required

Substitute parts are grouped into two categories based on product status and availability: Active production parts and Last Time Buy / Discontinued parts. All listed substitutes maintain electrical and mechanical compatibility within the specified parameter ranges.

Parameter Comparison

Part Number	Manufacturer	Product Status	Slew Rate (V/µs)	Gain BW (kHz)	Input Bias (nA)	Input Offset (mV)	Supply Current (mA)	Output Current (mA)	Supply Span Min (V)	Supply Span Max (V)	Temp Range (°C)	MSL
LM324WDT	Rohm Semiconductor	Obsolete	0.3	800	20	1	1	30	3	32	-40 ~ 85	1
AS324AMTR-E1	Diodes Incorporated	Active	—	—	20	2	1	40	3	36	-40 ~ 85	1
AS324AMTR-G1	Diodes Incorporated	Active	—	—	20	2	1	40	3	36	-40 ~ 85	3
AS324MTR-E1	Diodes Incorporated	Active	—	—	20	2	1	40	3	36	-40 ~ 85	3
AS324MTR-G1	Diodes Incorporated	Active	—	—	20	2	1	40	3	36	-40 ~ 85	1
LM124D	STMicroelectronics	Obsolete	0.4	1200	20	2	1.5	30	3	30	-55 ~ 125	1
LM124DG4	Texas Instruments	Last Time Buy	0.5	1200	20	3	1.4	30	3	30	-55 ~ 125	1
LM124DR	Texas Instruments	Active	0.5	1200	20	3	1.4	30	3	30	-55 ~ 125	1
LM124DRG4	Texas Instruments	Discontinued at DiGi Electronics	0.5	1200	20	3	1.4	30	3	30	-55 ~ 125	1
LM124DT	STMicroelectronics	Active	0.4	1300	20	2	1.5	40	3	30	-55 ~ 125	1
LM224D	STMicroelectronics	Active	0.4	1200	20	2	1.5	40	3	30	-40 ~ 105	1

Engineering Selection Recommendations

Active Production Substitutes (Recommended for New Designs):

The Diodes Incorporated AS324 series (AS324AMTR-E1, AS324AMTR-G1, AS324MTR-E1, AS324MTR-G1) and Texas Instruments LM124DR represent the primary substitution path. These parts maintain active production status, ensuring long-term availability and supply chain stability. The AS324 variants provide enhanced output current capability (40 mA versus 30 mA) and extended maximum supply voltage (36 V versus 32 V), offering improved performance margins. All active substitutes maintain ROHS3 compliance and MSL ratings suitable for standard manufacturing processes.

Secondary Substitutes (Existing Design Compatibility):

The STMicroelectronics LM124DT and LM224D provide functional equivalence with extended operating temperature ranges (-55°C ~ 125°C and -40°C ~ 105°C respectively), beneficial for applications requiring broader thermal performance. These parts are currently in active production status. The LM124DT offers increased output current (40 mA) and higher gain bandwidth product (1.3 MHz), while the LM224D provides a balanced performance profile with 1.2 MHz gain bandwidth product.

Discontinued / Last Time Buy Substitutes:

The Texas Instruments LM124DG4 and LM124DRG4 are designated as Last Time Buy or Discontinued at DiGi Electronics. These parts remain electrically compatible but should be considered only for existing production runs or applications where supply continuity is not critical. The LM124D from STMicroelectronics is classified as obsolete and carries similar supply risk as the primary LM324WDT.

Compliance and Certification:

All listed substitute parts maintain ROHS3 compliance and REACH Unaffected status, consistent with the original LM324WDT. Moisture Sensitivity Level (MSL) ratings range from 1 (Unlimited) to 3 (168 Hours), with MSL-1 parts preferred for applications with extended storage or high-humidity environments.

Frequently Asked Questions (FAQ)

Q: Can the AS324AMTR-E1 directly replace the LM324WDT in existing designs?

A: Yes. The AS324AMTR-E1 maintains electrical and mechanical compatibility across all critical parameters: 4-circuit general-purpose amplifier configuration, 14-SOIC package, identical input bias current (20 nA), and overlapping supply voltage range (3 V to 36 V). The AS324AMTR-E1 provides superior output current capability (40 mA versus 30 mA) and extended maximum supply voltage, making it a direct functional replacement.

Q: What is the difference between AS324AMTR-E1 and AS324MTR-E1?

A: Both parts are manufactured by Diodes Incorporated with identical electrical specifications. The primary difference is the Moisture Sensitivity Level (MSL): AS324AMTR-E1 is MSL-1 (Unlimited), while AS324MTR-E1 is MSL-3 (168 Hours). For applications with extended storage periods or high-humidity manufacturing environments, the AS324AMTR-E1 is preferred.

Q: Why do some substitute parts have higher gain bandwidth products than the LM324WDT?

A: The LM124 series (LM124DR, LM124DT, LM124DG4) and LM224D feature gain bandwidth products of 1.2 to 1.3 MHz compared to the LM324WDT's 800 kHz. This represents enhanced frequency response capability. These parts remain functionally compatible for applications designed around the LM324WDT, as higher bandwidth does not create incompatibility with existing circuit designs.

Q: Are there supply voltage limitations when substituting with LM124 series parts?

A: Yes. The LM124 series (all variants) has a maximum supply voltage of 30 V, compared to the LM324WDT's 32 V maximum. Applications operating at supply voltages between 30 V and 32 V require the AS324 series or LM224D, which support 36 V and 30 V maximum respectively. Verify your application's supply voltage specification before part selection.

Q: Which substitute part offers the best long-term availability?

A: The Diodes Incorporated AS324MTR-G1 and AS324AMTR-E1 are recommended for long-term availability, with inventory levels exceeding 196,000 and 20,600 units respectively. The Texas Instruments LM124DR also maintains active production status with 171,766 units in stock. These three parts represent the most stable sourcing options.

Q: Can I use LM124DG4 or LM124DRG4 for new production designs?

A: The LM124DG4 is designated Last Time Buy, and LM124DRG4 is Discontinued at DiGi Electronics. While electrically compatible, these parts are not recommended for new production designs due to limited availability and supply discontinuation. Use active production alternatives such as LM124DR, AS324MTR-G1, or AS324AMTR-E1 instead.

Q: What is the significance of the 14-SOIC versus 14-SO package designation?

A: Both designations refer to the same 14-pin small-outline integrated circuit package with 0.154" (3.90mm) width. The terminology difference reflects manufacturer nomenclature conventions. All listed parts are mechanically compatible and can be used interchangeably in PCB designs specifying 14-SOIC or 14-SO footprints.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance and REACH Unaffected status, consistent with the original LM324WDT. This ensures compatibility with modern manufacturing processes and regulatory requirements.

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