LMX321AXK-T Equivalent & Substitute Parts

Part Overview

The LMX321AXK-T is a general purpose operational amplifier manufactured by Analog Devices Inc./Maxim Integrated, featuring rail-to-rail output capability in a 5-pin SC-70 surface mount package. This device is classified as obsolete, indicating discontinuation from active production. Identification of equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this amplifier topology.

Key Parameters

Parameter	Value	Unit
Amplifier Type	General Purpose	—
Number of Circuits	1	—
Output Type	Rail-to-Rail	—
Slew Rate	1	V/µs
Gain Bandwidth Product	1.3	MHz
Current - Input Bias	18	nA
Voltage - Input Offset	1	mV
Current - Supply	120	µA
Current - Output / Channel	28	mA
Voltage - Supply Span (Min)	2.3	V
Voltage - Supply Span (Max)	7	V
Operating Temperature	-40 to 125	°C
Mounting Type	Surface Mount	—
Package / Case	5-TSSOP, SC-70-5, SOT-353	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the LMX321AXK-T is determined by the following critical parameters:

Primary Substitution Criteria:

Amplifier Type: General Purpose
Number of Circuits: 1
Output Type: Rail-to-Rail
Package / Case: 5-TSSOP, SC-70-5, SOT-353 (compatible pinout and form factor)
Mounting Type: Surface Mount
Operating Temperature Range: Minimum -40°C to 125°C coverage
RoHS Status: ROHS3 Compliant

Secondary Compatibility Parameters:

Gain Bandwidth Product: 1 MHz to 1.5 MHz range
Slew Rate: 0.48 V/µs to 1 V/µs range
Current - Supply: 36 µA to 200 µA range
Voltage - Supply Span: Minimum 1.8 V to 2.7 V; Maximum 5 V to 7 V
Current - Input Bias: 1 pA to 27 nA range
Voltage - Input Offset: 300 µV to 4.5 mV range

Substitute parts must maintain functional equivalence within these parameter boundaries while supporting the same package footprint and surface mount assembly process.

Parameter Comparison

Parameter	LMX321AXK-T (Main)	MAX9636AXT+T	APX321SEG-7	LMV301SQ3T2G	LMV321IDCKR	LMV321M7X/NOPB	LMV321SEG-7	LMV321SQ3T2G	LMV931SQ3T2G	LMX321ICT	MCP6001T-E/LT
Amplifier Type	General Purpose	General Purpose	General Purpose	General Purpose	Voltage Feedback	General Purpose	General Purpose	General Purpose	General Purpose	General Purpose	General Purpose
Number of Circuits	1	1	1	1	1	1	1	1	1	1	1
Output Type	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail	Rail-to-Rail
Slew Rate (V/µs)	1	0.9	1	1	—	1	1	1	0.48	0.7	0.6
Gain Bandwidth Product (MHz)	1.3	1.5	1	1	1	1	1	1	1.5	1.3	1
Current - Input Bias (nA)	18	0.0001	15	0.001	0.01	15	15	0.001	0.001	27	0.001
Voltage - Input Offset (mV)	1	0.3	1.7	1.7	0.8	1.7	1.7	1.7	1	4	4.5
Current - Supply (µA)	120	36	110	200	45	130	110	130	116	130	100
Current - Output / Channel (mA)	28	55	90	160	25	—	90	160	100	70	23
Voltage - Supply Span Min (V)	2.3	2.1	2.5	1.8	2.1	2.7	2.7	2.7	1.8	2.3	1.8
Voltage - Supply Span Max (V)	7	5.5	5.5	5	5.5	5.5	5.5	5.5	5.5	5.5	6
Operating Temperature (°C)	-40 to 125	-40 to 125	-40 to 85	-40 to 85	-25 to 85	-40 to 85	-40 to 85	-40 to 85	-40 to 125	-40 to 125	-40 to 125
Package / Case	5-TSSOP, SC-70-5, SOT-353	6-TSSOP, SC-88, SOT-363	5-TSSOP, SC-70-5, SOT-353	5-TSSOP, SC-70-5, SOT-353	5-TSSOP, SC-70-5, SOT-353	5-TSSOP, SC-70-5, SOT-353	5-TSSOP, SC-70-5, SOT-353	5-TSSOP, SC-70-5, SOT-353	5-TSSOP, SC-70-5, SOT-353	5-TSSOP, SC-70-5, SOT-353	5-TSSOP, SC-70-5, SOT-353
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active	Active	Active	Active

Engineering Selection Recommendations

Primary Substitutes (Highest Compatibility):

The following parts provide direct substitution with full parameter compatibility and active product status:

LMV321SQ3T2G (onsemi) and LMV321SEG-7 (Diodes Incorporated) are the preferred substitutes. Both devices maintain the 5-TSSOP SC-70-5 SOT-353 package footprint, support the full -40°C to 125°C operating temperature range of the original part, and deliver equivalent electrical performance across all critical parameters. Both are ROHS3 compliant with MSL 1 (LMV321SQ3T2G) or MSL 3 (LMV321SEG-7) ratings. LMV321SQ3T2G offers superior input bias current performance (1 nA) and higher output current capability (160 mA).

LMX321ICT (STMicroelectronics) provides direct functional equivalence with identical package designation and full temperature range support (-40°C to 125°C). This part maintains the LMX321 base product number lineage and delivers 1.3 MHz gain bandwidth product matching the original specification.

MCP6001T-E/LT (Microchip Technology) operates across an extended supply voltage range (1.8 V to 6 V) and maintains full temperature coverage (-40°C to 125°C). This device provides superior input bias current performance (1 pA) and is available in high inventory quantities.

LMV931SQ3T2G (onsemi) extends the gain bandwidth product to 1.5 MHz while maintaining full temperature range support (-40°C to 125°C) and the required package footprint. This part is suitable for applications requiring enhanced frequency response.

Secondary Substitutes (Conditional Compatibility):

APX321SEG-7 (Diodes Incorporated) and LMV301SQ3T2G (onsemi) are compatible substitutes with the following operational constraints: both devices support only -40°C to 85°C operating temperature range, which restricts use in applications requiring the full -40°C to 125°C specification of the original part. Both maintain the required package footprint and rail-to-rail output configuration.

LMV321IDCKR (UMW) operates within -25°C to 85°C temperature range, further limiting applicability to designs requiring extended low-temperature operation below -25°C.

MAX9636AXT+T (Analog Devices Inc./Maxim Integrated) utilizes a 6-pin SC-88 SOT-363 package, which differs from the 5-pin SC-70-5 footprint of the original part. This package incompatibility requires PCB redesign and is not recommended for direct substitution in existing designs.

Compliance and Certification:

All substitute parts listed maintain ROHS3 compliance and are manufactured to current environmental standards. Moisture sensitivity levels range from MSL 1 (unlimited) to MSL 3 (168 hours), requiring appropriate handling protocols during assembly and storage.

Frequently Asked Questions (FAQ)

Q: Can MAX9636AXT+T be used as a direct replacement for LMX321AXK-T?

A: MAX9636AXT+T is not a direct replacement due to package incompatibility. The MAX9636AXT+T uses a 6-pin SC-88 SOT-363 package, while the LMX321AXK-T requires a 5-pin SC-70-5 SOT-353 package. Pinout differences prevent direct PCB substitution without circuit board redesign.

Q: Which substitute part offers the best input bias current performance?

A: LMV301SQ3T2G, LMV321SQ3T2G, LMV931SQ3T2G, and MCP6001T-E/LT all deliver input bias current of 1 pA or 0.001 nA, representing superior performance compared to the original LMX321AXK-T specification of 18 nA. These parts are suitable for high-impedance input applications.

Q: Are there temperature range limitations with substitute parts?

A: Yes. LMV321M7X/NOPB, LMV321SEG-7, APX321SEG-7, and LMV301SQ3T2G support only -40°C to 85°C operation, which does not cover the full -40°C to 125°C range of the original part. LMV321IDCKR is limited to -25°C to 85°C. For applications requiring full temperature coverage, select LMV321SQ3T2G, LMX321ICT, LMV931SQ3T2G, or MCP6001T-E/LT.

Q: What is the difference between LMV321SQ3T2G and LMV321SEG-7?

A: Both parts maintain identical electrical specifications and package footprint. The primary difference is moisture sensitivity level: LMV321SQ3T2G is MSL 1 (unlimited), while LMV321SEG-7 is MSL 3 (168 hours). LMV321SQ3T2G is preferred for applications with extended storage or high-humidity environments.

Q: Can MCP6001T-E/LT operate at the maximum supply voltage of the original part?

A: MCP6001T-E/LT supports supply voltages up to 6 V, which is below the 7 V maximum of the LMX321AXK-T. For applications requiring operation at 7 V supply voltage, use LMX321ICT or LMV321SQ3T2G, both of which support 5.5 V maximum supply voltage. Verify actual circuit requirements before selection.

Q: What is the inventory status of substitute parts?

A: All listed substitute parts are in active production with substantial inventory availability. LMV321SQ3T2G (21,050 units), LMV321SEG-7 (25,200 units), LMX321ICT (38,280 units), and MCP6001T-E/LT (100,773 units) are available in high quantities, ensuring supply chain continuity.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed in this reference maintain ROHS3 compliance and are suitable for applications subject to environmental regulations requiring lead-free and restricted substance compliance.

Q: Which substitute offers the highest output current capability?

A: LMV301SQ3T2G and LMV321SQ3T2G both deliver 160 mA output current per channel, compared to 28 mA for the original LMX321AXK-T. These parts are suitable for applications requiring higher load driving capability.

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