LMX324ASD Equivalent & Substitute Parts

Part Overview

The LMX324ASD is a general-purpose operational amplifier featuring four independent circuits in a 14-SOIC surface-mount package. Manufactured by Analog Devices Inc./Maxim Integrated, this device provides rail-to-rail output capability with a 1.3 MHz gain-bandwidth product and operates across a 2.3 V to 7 V supply range. The LMX324ASD is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. Substitute parts must maintain functional compatibility while meeting current availability and compliance requirements.

Key Parameters

Parameter	LMX324ASD Value
Amplifier Type	General Purpose
Number of Circuits	4
Output Type	Rail-to-Rail
Package / Case	14-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Slew Rate	1 V/µs
Gain Bandwidth Product	1.3 MHz
Current - Input Bias	18 nA
Voltage - Input Offset	1 mV
Current - Supply	480 µA (x4 Channels)
Current - Output / Channel	70 mA
Voltage - Supply Span (Min)	2.3 V
Voltage - Supply Span (Max)	7 V
Operating Temperature	-40°C ~ 125°C
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the LMX324ASD is determined by the following critical parameters:

Mechanical Compatibility: All substitute parts must use the 14-SOIC (0.154", 3.90mm Width) surface-mount package to ensure PCB footprint compatibility without redesign.

Functional Requirements: Substitute parts must provide four independent operational amplifier circuits with rail-to-rail output capability. The amplifier type (general purpose or voltage feedback) and number of circuits are non-negotiable specifications.

Electrical Operating Range: The supply voltage span must encompass or exceed the original 2.3 V to 7 V range. Substitute parts with narrower supply ranges may not function in all original applications.

Performance Characteristics: Slew rate, gain-bandwidth product, input bias current, input offset voltage, and output current per channel define the signal-processing capability. Substitutes with lower performance may not meet application requirements; higher performance substitutes are generally acceptable.

Environmental and Compliance: Operating temperature range, RoHS compliance status, and moisture sensitivity level determine suitability for specific manufacturing and deployment environments.

Substitute parts are grouped into two categories: Direct Replacements (matching or exceeding all key parameters with active product status) and Functional Alternatives (meeting core requirements with acceptable trade-offs in performance or supply range).

Parameter Comparison

Parameter	LMX324ASD	MAX4294ESD+	AD8544ARZ	ISL28413FBZ	LMV324BG-13	LMV324DR2G	LMV324ID
Manufacturer	Analog Devices Inc./Maxim Integrated	Analog Devices Inc./Maxim Integrated	Analog Devices Inc.	Renesas Electronics Corporation	Diodes Incorporated	onsemi	Texas Instruments
Product Status	Obsolete	Active	Active	Active	Active	Active	Last Time Buy
Number of Circuits	4	4	4	4	4	4	4
Output Type	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail
Package / Case	14-SOIC	14-SOIC	14-SOIC	14-SOIC	14-SOIC	14-SOIC	14-SOIC
Slew Rate (V/µs)	1	0.2	0.92	1	1	1	1
Gain Bandwidth Product (MHz)	1.3	0.5	1	2	1	1	1
Current - Input Bias (nA)	18	15	0.004	0.003	15	1	15
Voltage - Input Offset (mV)	1	0.2	1	0.5	1.7	1.7	1.7
Current - Supply (µA x4)	480	100	45	90	340	100	410
Current - Output / Channel (mA)	70	20	30	22	90	160	40
Voltage - Supply Span (Min)	2.3 V	1.8 V	2.7 V	1.8 V	2.7 V	2.7 V	2.7 V
Voltage - Supply Span (Max)	7 V	5.5 V	5.5 V	5.5 V	5.5 V	5.5 V	5.5 V
Operating Temperature	-40°C ~ 125°C	-40°C ~ 85°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 85°C	-40°C ~ 125°C
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	2 (1 Year)	3 (168 Hours)	3 (168 Hours)	1 (Unlimited)

Engineering Selection Recommendations

For Active Production with RoHS Compliance Requirements:

The AD8544ARZ, AD8544ARZ-REEL, AD8544ARZ-REEL7, and AD8544WARZ-R7 are preferred substitutes. These Analog Devices parts maintain the original operating temperature range (-40°C to 125°C), provide ROHS3 compliance, and offer MSL 1 (unlimited) moisture sensitivity. The AD8544 base product delivers 0.92 V/µs slew rate and 1 MHz gain-bandwidth product, closely matching the LMX324ASD performance envelope. Multiple packaging options (Tube, Cut Tape & Digi-Reel, Tape & Reel) support various procurement workflows. Inventory availability ranges from 1,414 to 26,342 units across variants.

For Low-Power Applications with Extended Supply Range:

The ISL28413FBZ and ISL28413FBZ-T7 (Renesas Electronics) offer superior performance with 2 MHz gain-bandwidth product and exceptionally low input bias current (3 pA). These parts support the extended 1.8 V to 5.5 V supply range, enabling operation in battery-powered and low-voltage systems. ROHS3 compliance and -40°C to 125°C operating temperature ensure compatibility with industrial applications. MSL 2 (1 Year) requires standard moisture control during storage and assembly.

For Cost-Optimized Designs with Reduced Supply Voltage:

The MAX4294ESD+ provides the lowest supply current (100 µA total) and operates from 1.8 V, making it suitable for power-constrained applications. However, the reduced maximum supply voltage (5.5 V versus 7 V) and narrower operating temperature range (-40°C to 85°C) limit applicability to designs not requiring the full original voltage span or extended high-temperature operation.

For Designs Tolerating Reduced Output Current:

The LMV324BG-13 (Diodes Incorporated) and LMV324DR2G (onsemi) provide rail-to-rail operation in the 14-SOIC package with ROHS3 compliance. The LMV324BG-13 supports the full -40°C to 125°C temperature range but requires MSL 3 moisture control. The LMV324DR2G offers superior output current capability (160 mA per channel) but operates only to 85°C and requires MSL 3 handling.

For Legacy System Maintenance:

The LMV324ID (Texas Instruments) maintains Last Time Buy status with active inventory (3,200 units). This part bridges obsolete LMX324ASD designs to modern supply chains while preserving the original -40°C to 125°C operating range and MSL 1 moisture sensitivity. Selection of this part should account for its limited future availability.

Frequently Asked Questions (FAQ)

Q: Can I directly replace LMX324ASD with any of these substitute parts without PCB modification?

A: Yes, all listed substitute parts use the identical 14-SOIC (0.154", 3.90mm Width) surface-mount package. PCB footprints and pin assignments are compatible. However, verify that your application's supply voltage range and operating temperature requirements align with the substitute part's specifications before implementation.

Q: What is the primary limitation of the MAX4294ESD+ as a substitute?

A: The MAX4294ESD+ operates only to 85°C maximum, compared to the LMX324ASD's 125°C upper limit. Applications requiring extended high-temperature operation must select alternatives such as AD8544ARZ, ISL28413FBZ, or LMV324ID. Additionally, the maximum supply voltage is limited to 5.5 V, restricting use in systems requiring the original 7 V maximum.

Q: Why do some substitute parts have different moisture sensitivity levels (MSL)?

A: Moisture sensitivity level reflects the component's susceptibility to moisture absorption during storage and assembly. MSL 1 (unlimited) parts require no special moisture control. MSL 2 and MSL 3 parts require controlled storage environments and may require baking before reflow soldering. Select MSL 1 parts (AD8544ARZ variants, LMV324ID) for manufacturing environments without advanced moisture management capabilities.

Q: Which substitute offers the best performance improvement over the LMX324ASD?

A: The ISL28413FBZ provides the highest gain-bandwidth product (2 MHz versus 1.3 MHz) and the lowest input bias current (3 pA versus 18 nA). This part is suitable for precision signal-conditioning applications requiring low offset drift and high-frequency response. Trade-offs include MSL 2 moisture sensitivity and reduced maximum supply voltage (5.5 V).

Q: Are all substitute parts RoHS compliant?

A: All listed substitute parts are ROHS3 compliant. The original LMX324ASD is RoHS non-compliant. If your application or customer requirements mandate RoHS compliance, any of the substitute parts satisfy this requirement.

Q: What is the difference between AD8544ARZ, AD8544ARZ-REEL, AD8544ARZ-REEL7, and AD8544WARZ-R7?

A: These are packaging variants of the same AD8544 base product. AD8544ARZ is supplied in Tube packaging. AD8544ARZ-REEL and AD8544ARZ-REEL7 are supplied on Cut Tape & Digi-Reel. AD8544WARZ-R7 is supplied on Tape & Reel (TR). All variants share identical electrical specifications and performance. Selection depends on your procurement and assembly equipment compatibility.

Q: Can I use LMV324DR2G in applications requiring operation above 85°C?

A: No. The LMV324DR2G is rated only to 85°C maximum operating temperature. For applications requiring -40°C to 125°C operation, select AD8544ARZ, ISL28413FBZ, or LMV324ID instead.

Q: What is the significance of "Last Time Buy" status for LMV324ID?

A: Last Time Buy indicates that Texas Instruments will discontinue this part after current inventory is exhausted. While 3,200 units are currently available, this part should not be selected for new long-term production designs. Use LMV324ID only for legacy system maintenance or short-term production runs. For new designs, select active-status alternatives such as AD8544ARZ or ISL28413FBZ.

Q: How do I determine which substitute is best for my specific application?

A: Evaluate your design requirements against these criteria in order of priority: (1) Supply voltage range—ensure the substitute's minimum and maximum ratings encompass your system voltage; (2) Operating temperature range—select parts rated for your full temperature specification; (3) Output current per channel—verify the substitute can deliver required load current; (4) Compliance requirements—confirm RoHS and moisture sensitivity compatibility with your manufacturing process; (5) Performance margin—higher slew rate and gain-bandwidth product provide design margin for signal fidelity.

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