INA128UAE4 Equivalent & Substitute Parts

Part Overview

The INA128UAE4 is an instrumentation amplifier manufactured by Texas Instruments, designed for single-circuit applications in 8-SOIC surface mount packaging. This device is classified as obsolete, which necessitates identification of active equivalent and substitute components for ongoing design support and procurement.

The INA128UAE4 operates across a wide supply voltage range of 4.5 V to 36 V with an operating temperature range of -40°C to 125°C. Its primary application domain includes precision signal conditioning and measurement circuits requiring low input bias current and minimal input offset voltage.

Key Parameters

Parameter	Value	Unit
Amplifier Type	Instrumentation	—
Number of Circuits	1	—
Slew Rate	4	V/µs
-3dB Bandwidth	1.3	MHz
Current - Input Bias	2	nA
Voltage - Input Offset	25	µV
Current - Supply	700	µA
Current - Output / Channel	15	mA
Voltage - Supply Span (Min)	4.5	V
Voltage - Supply Span (Max)	36	V
Operating Temperature	-40 to 125	°C
Package / Case	8-SOIC (0.154", 3.90mm Width)	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level	3 (168 Hours)	—

Substitute Part Grouping Explanation

Substitution of the INA128UAE4 is determined by strict equivalence across the following critical parameters:

Primary Substitution Criteria:

Amplifier Type: Instrumentation
Number of Circuits: 1
Package / Case: 8-SOIC (0.154", 3.90mm Width)
Mounting Type: Surface Mount
Supply Voltage Range: Minimum 4.5 V, Maximum 36 V
RoHS Compliance: ROHS3 Compliant

Secondary Compatibility Parameters:

Slew Rate: 4 V/µs (INA128UAE4 baseline)
-3dB Bandwidth: 1.3 MHz (INA128UAE4 baseline)
Current - Input Bias: 2 nA (INA128UAE4 baseline)
Voltage - Input Offset: 25 µV (INA128UAE4 baseline)

Substitute parts are grouped into two categories:

Category 1: Direct Manufacturer Equivalents (Texas Instruments INA128 Series) The INA128UA represents the active production equivalent from Texas Instruments. This part maintains identical electrical specifications to the INA128UAE4 across all critical parameters while offering active product status and improved availability.

Category 2: Functional Alternatives (Analog Devices AD620 and AD621 Series) The AD620 and AD621 series from Analog Devices provide instrumentation amplifier functionality within the same 8-SOIC package. These parts operate within the required supply voltage range and maintain surface mount compatibility. However, electrical performance characteristics differ in specific parameters including slew rate, bandwidth, input bias current, and input offset voltage specifications.

Parameter Comparison

Parameter	INA128UAE4	INA128UA	AD620ARZ	AD620BRZ	AD621ARZ
Manufacturer	Texas Instruments	Texas Instruments	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.
Product Status	Obsolete	Active	Active	Active	Active
Slew Rate (V/µs)	4	4	1.2	1.2	1.2
-3dB Bandwidth (MHz)	1.3	1.3	1	1	0.8
Current - Input Bias (nA)	2	2	0.5	0.5	0.5
Voltage - Input Offset (µV)	25	25	30	15	75
Current - Supply (µA)	700	700	900	900	900
Current - Output / Channel (mA)	15	15	18	18	18
Voltage - Supply Span (Min) (V)	4.5	4.5	4.6	4.6	4.6
Voltage - Supply Span (Max) (V)	36	36	36	36	36
Operating Temperature (°C)	-40 to 125	-40 to 125	-40 to 85	-40 to 85	-40 to 85
Package / Case	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level	3 (168 Hours)	3 (168 Hours)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Primary Selection: INA128UA

The INA128UA from Texas Instruments is the recommended direct substitute for the obsolete INA128UAE4. This part maintains complete electrical and mechanical equivalence across all specified parameters. The INA128UA is in active production status with established supply chain availability (1,837 pcs in stock). Both parts share identical slew rate (4 V/µs), bandwidth (1.3 MHz), input bias current (2 nA), and input offset voltage (25 µV) specifications. The INA128UA is supplied in tube packaging and maintains ROHS3 compliance with identical moisture sensitivity classification.

Secondary Selection: AD620 Series (Analog Devices)

The AD620ARZ, AD620BRZ, and their packaging variants (AD620ARZ-REEL, AD620ARZ-REEL7, AD620BRZ-R7, AD620BRZ-RL) represent functional alternatives when INA128UA availability is constrained. These parts operate within the required 4.6 V to 36 V supply range and maintain 8-SOIC surface mount compatibility. The AD620 series exhibits superior input bias current performance (0.5 nA versus 2 nA) and improved moisture sensitivity (MSL 1 versus MSL 3). However, the AD620 series operates at reduced slew rate (1.2 V/µs versus 4 V/µs) and lower bandwidth (1 MHz versus 1.3 MHz). The AD620BRZ variant offers the lowest input offset voltage (15 µV) among the AD620 options. Operating temperature range is limited to -40°C to 85°C, which excludes applications requiring operation above 85°C.

Tertiary Selection: AD621 Series (Analog Devices)

The AD621ARZ, AD621ARZ-R7, and AD621ARZ-RL represent additional functional alternatives with further bandwidth reduction (800 kHz) and elevated input offset voltage (75 µV). These parts are suitable only for applications where reduced bandwidth and higher offset voltage are acceptable trade-offs for improved input bias current performance and moisture sensitivity characteristics.

Compliance and Certification:

All recommended substitutes maintain ROHS3 compliance and REACH unaffected status, consistent with the original INA128UAE4 specification. All parts are classified under ECCN EAR99 and HTSUS 8542.33.0001.

Frequently Asked Questions (FAQ)

Q1: Can the INA128UA directly replace the INA128UAE4 without circuit modification?

A: Yes. The INA128UA is electrically and mechanically equivalent to the INA128UAE4 across all specified parameters. No circuit modifications are required. Both parts operate identically within the 4.5 V to 36 V supply range, maintain the same slew rate and bandwidth characteristics, and are packaged in identical 8-SOIC surface mount configuration.

Q2: What are the key differences between the INA128UA and AD620 series substitutes?

A: The primary differences are slew rate, bandwidth, and operating temperature range. The INA128UA maintains 4 V/µs slew rate and 1.3 MHz bandwidth identical to the original INA128UAE4. The AD620 series operates at 1.2 V/µs slew rate and 1 MHz bandwidth. The INA128UA supports operation to 125°C, while AD620 series is limited to 85°C. The AD620 series offers superior input bias current (0.5 nA) and improved moisture sensitivity (MSL 1).

Q3: Which substitute should be selected for high-temperature applications above 85°C?

A: The INA128UA is the only recommended substitute that maintains operation to 125°C, matching the original INA128UAE4 specification. The AD620 and AD621 series are limited to 85°C maximum operating temperature and are unsuitable for applications requiring higher temperature operation.

Q4: Are there packaging format options available for the substitute parts?

A: Yes. The INA128UA is supplied in tube packaging. The AD620 series offers multiple packaging options: tube (AD620ARZ), cut tape with Digi-Reel (AD620ARZ-REEL, AD620ARZ-REEL7, AD620BRZ-R7), and tape & reel (AD620BRZ-RL). The AD621 series offers tube (AD621ARZ), cut tape with Digi-Reel (AD621ARZ-R7), and tape & reel (AD621ARZ-RL) formats. Selection should be based on assembly process requirements and procurement volume.

Q5: What is the significance of the MSL (Moisture Sensitivity Level) difference between INA128UA and AD620 series?

A: The INA128UA maintains MSL 3 (168 hours) identical to the original INA128UAE4. The AD620 and AD621 series feature MSL 1 (unlimited), indicating superior moisture resistance and reduced baking requirements during storage and handling. MSL 1 classification is advantageous for extended shelf life and reduced manufacturing process constraints.

Q6: Can the AD621 series be used as a substitute for applications requiring the lowest input offset voltage?

A: No. The AD621 series exhibits the highest input offset voltage (75 µV) among all available substitutes, making it unsuitable for applications requiring precision offset performance. The AD620BRZ offers the lowest input offset voltage (15 µV) among the Analog Devices alternatives, though this remains higher than the INA128UA specification (25 µV).

Q7: What inventory considerations should guide substitute part selection?

A: The INA128UA maintains 1,837 pcs in stock. The AD620 series offers significantly higher availability: AD620ARZ-REEL (110,558 pcs), AD620BRZ-R7 (36,091 pcs), and AD620BRZ (15,146 pcs). The AD621 series maintains lower inventory: AD621ARZ-R7 (3,542 pcs) and AD621ARZ-RL (2,531 pcs). Procurement decisions should balance electrical performance requirements against supply chain availability.

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