OPA228UG4 Equivalent & Substitute Parts

Part Overview

The OPA228UG4 is a general purpose operational amplifier manufactured by Texas Instruments, housed in an 8-SOIC surface mount package. This device is classified as obsolete product status, which necessitates identification of active equivalent and substitute components for ongoing design requirements and procurement needs. The OPA228UG4 delivers a gain bandwidth product of 33 MHz with a slew rate of 11V/µs, suitable for general purpose amplification applications across industrial and commercial temperature ranges.

Key Parameters

Parameter	Value
Manufacturer Part Number	OPA228UG4
Manufacturer	Texas Instruments
Category	Linear, Amplifiers
Amplifier Type	General Purpose
Number of Circuits	1
Package / Case	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Slew Rate	11V/µs
Gain Bandwidth Product	33 MHz
Current - Input Bias	2.5 nA
Voltage - Input Offset	5 µV
Current - Supply	3.7 mA
Current - Output / Channel	45 mA
Voltage - Supply Span (Min)	5 V
Voltage - Supply Span (Max)	36 V
Operating Temperature	-40°C ~ 85°C
Product Status	Obsolete
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	3 (168 Hours)

Substitute Part Grouping Explanation

Substitution of the OPA228UG4 is determined by strict alignment of the following critical parameters:

Package Compatibility: All substitute parts must use the 8-SOIC surface mount package to ensure direct PCB footprint compatibility without layout modifications.

Supply Voltage Range: Substitute parts must support the minimum 5V and maximum 36V supply span to function within the same power distribution architecture.

Operating Temperature Range: Substitute parts must cover the -40°C to 85°C operating window or a superset thereof.

Amplifier Classification: Substitute parts are grouped by amplifier type (General Purpose or Instrumentation). General purpose amplifiers are primary substitutes; instrumentation amplifiers are secondary substitutes with different functional characteristics.

Electrical Performance: Slew rate, gain bandwidth product, input bias current, input offset voltage, and output current capacity determine functional equivalence within application-specific constraints.

Compliance & Certification: All substitute parts maintain ROHS3 compliance and REACH unaffected status, ensuring regulatory alignment with the original component.

Parameter Comparison

Parameter	OPA228UG4	OPA228U	OP37GS8#TRPBF	OP37GSZ	OP37GSZ-REEL7	AD8421ARZ-R7
Manufacturer	Texas Instruments	Texas Instruments	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.
Amplifier Type	General Purpose	General Purpose	General Purpose	General Purpose	General Purpose	Instrumentation
Package / Case	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Slew Rate	11V/µs	11V/µs	17V/µs	17V/µs	17V/µs	35V/µs
Gain Bandwidth Product	33 MHz	33 MHz	63 MHz	63 MHz	63 MHz	10 MHz
Current - Input Bias	2.5 nA	2.5 nA	15 nA	15 nA	15 nA	1 nA
Voltage - Input Offset	5 µV	5 µV	30 µV	30 µV	30 µV	60 µV
Current - Supply	3.7 mA	3.7 mA	—	—	—	2 mA
Current - Output / Channel	45 mA	45 mA	—	—	—	65 mA
Voltage - Supply Span (Min)	5 V	5 V	8 V	8 V	8 V	5 V
Voltage - Supply Span (Max)	36 V	36 V	36 V	36 V	36 V	36 V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-25°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	3 (168 Hours)	2 (1 Year)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Primary Substitute: OPA228U

The OPA228U is the direct active equivalent to the OPA228UG4. Both components share identical electrical specifications including 11V/µs slew rate, 33 MHz gain bandwidth product, 2.5 nA input bias current, and 5 µV input offset voltage. The OPA228U maintains active product status with improved moisture sensitivity rating (MSL 2 versus MSL 3), ensuring superior reliability in storage and handling. Supply voltage range, operating temperature span, and package configuration are identical. This component is the recommended primary substitute for direct replacement applications.

Secondary Substitutes: OP37GS8#TRPBF, OP37GSZ, OP37GSZ-REEL7

The OP37 series (OP37GS8#TRPBF, OP37GSZ, OP37GSZ-REEL7) from Analog Devices Inc. provides enhanced electrical performance with 17V/µs slew rate and 63 MHz gain bandwidth product, representing approximately 50% improvement in both parameters. These components maintain 8-SOIC package compatibility and -40°C to 85°C operating temperature coverage. The OP37GS8#TRPBF variant operates at minimum 8V supply (versus 5V for OPA228UG4), which may require verification in low-voltage applications. OP37GSZ and OP37GSZ-REEL7 variants support the full 5V minimum supply requirement. All three variants carry MSL 1 rating and active product status. These substitutes are suitable for applications requiring higher slew rate and bandwidth performance within the same package footprint.

Tertiary Substitute: AD8421ARZ-R7

The AD8421ARZ-R7 is an instrumentation amplifier from Analog Devices Inc. with fundamentally different functional characteristics compared to the general purpose OPA228UG4. This component features 35V/µs slew rate, 1 nA input bias current, and 65 mA output current capability. The 10 MHz gain bandwidth product is lower than the OPA228UG4. The AD8421ARZ-R7 is classified as an instrumentation amplifier rather than general purpose, indicating specialized input stage design for differential signal acquisition. This substitute is applicable only in instrumentation-specific applications where the functional architecture aligns with design requirements. MSL 1 rating and active product status ensure superior availability and handling characteristics.

Compliance & Availability Considerations

All substitute parts maintain ROHS3 compliance and REACH unaffected status, ensuring regulatory alignment. The OPA228U offers the highest inventory availability (1520 pcs) among direct equivalents. The OP37GSZ-REEL7 variant provides the largest inventory position (55300 pcs) among enhanced-performance alternatives. Selection should prioritize product status (active versus obsolete) and moisture sensitivity level for long-term supply chain stability.

Frequently Asked Questions (FAQ)

Q: Can OPA228U directly replace OPA228UG4 without circuit modifications?

A: Yes. The OPA228U is a direct functional equivalent with identical electrical specifications and 8-SOIC package configuration. No circuit modifications are required. The primary difference is improved moisture sensitivity rating (MSL 2 versus MSL 3) and active product status, both favorable for new designs and procurement.

Q: What is the difference between OPA228U and OP37GSZ substitutes?

A: The OPA228U maintains identical electrical performance to the OPA228UG4 (11V/µs slew rate, 33 MHz bandwidth). The OP37GSZ provides enhanced performance with 17V/µs slew rate and 63 MHz bandwidth, representing approximately 50% improvement in both parameters. Selection depends on application requirements for signal speed and frequency response. Both maintain 8-SOIC package compatibility and -40°C to 85°C operating temperature range.

Q: Why does OP37GS8#TRPBF specify 8V minimum supply voltage while others specify 5V?

A: The OP37GS8#TRPBF variant has a minimum supply voltage specification of 8V, compared to 5V for OPA228UG4, OPA228U, OP37GSZ, and OP37GSZ-REEL7. Applications operating at 5V to 7.99V supply voltage must use OPA228U, OP37GSZ, or OP37GSZ-REEL7 variants. The OP37GS8#TRPBF is suitable only for applications with 8V or higher supply voltage.

Q: Is AD8421ARZ-R7 a suitable substitute for general purpose amplification?

A: The AD8421ARZ-R7 is an instrumentation amplifier with different functional architecture than the general purpose OPA228UG4. While both are 8-SOIC packaged operational amplifiers, the instrumentation amplifier design includes integrated input stage optimization for differential signal acquisition. This component is suitable only for applications specifically requiring instrumentation amplifier functionality. For general purpose amplification, OPA228U or OP37 series variants are appropriate substitutes.

Q: What does MSL rating mean and why does it differ among substitutes?

A: Moisture Sensitivity Level (MSL) indicates the maximum time a component can be exposed to ambient conditions (30°C, 60% relative humidity) before requiring baking prior to soldering. OPA228UG4 carries MSL 3 (168 hours maximum exposure). OPA228U carries MSL 2 (1 year maximum exposure). OP37 series and AD8421ARZ-R7 carry MSL 1 (unlimited exposure). Higher MSL ratings (lower numbers) indicate superior moisture resistance and reduced risk of solder joint defects. Substitutes with MSL 1 or 2 ratings provide improved reliability compared to the original MSL 3 component.

Q: Can OP37GSZ-REEL7 be used interchangeably with OP37GSZ?

A: OP37GSZ and OP37GSZ-REEL7 are electrically identical with identical specifications. The difference is packaging format: OP37GSZ is supplied in tube packaging, while OP37GSZ-REEL7 is supplied in cut tape and digi-reel format. Both are suitable for identical applications. Selection depends on procurement and assembly process requirements. OP37GSZ-REEL7 offers significantly higher inventory availability (55300 pcs versus 22805 pcs).

Q: What is the operating temperature range limitation for OP37GS8#TRPBF?

A: The OP37GS8#TRPBF variant specifies -25°C to 85°C operating temperature range, compared to -40°C to 85°C for OPA228UG4 and other substitutes. Applications requiring operation below -25°C must use OPA228U, OP37GSZ, OP37GSZ-REEL7, or AD8421ARZ-R7 variants. The OP37GS8#TRPBF is suitable only for applications with minimum operating temperature of -25°C or higher.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed (OPA228U, OP37GS8#TRPBF, OP37GSZ, OP37GSZ-REEL7, AD8421ARZ-R7) are ROHS3 compliant and REACH unaffected. Regulatory compliance is maintained across all substitutes, ensuring compatibility with environmental and hazardous substance restrictions.

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