OPA124UA Equivalent & Substitute Parts

Part Overview

The OPA124UA is a general-purpose operational amplifier manufactured by Texas Instruments in 8-SOIC surface mount packaging. This device is classified as obsolete, which necessitates identification of functionally equivalent substitute components for ongoing design support and production continuity. The OPA124UA operates across a wide supply voltage range of 10V to 36V with low input bias current characteristics typical of JFET-input amplifier architectures.

Key Parameters

Parameter	Value	Unit
Amplifier Type	General Purpose	—
Number of Circuits	1	—
Slew Rate	1.6	V/µs
Gain Bandwidth Product	1.5	MHz
Current - Input Bias	0.5	pA
Voltage - Input Offset	150	µV
Current - Supply	2.5	mA
Current - Output / Channel	10	mA
Voltage - Supply Span (Min)	10	V
Voltage - Supply Span (Max)	36	V
Operating Temperature	-25°C to 85°C	—
Package / Case	8-SOIC (0.154", 3.90mm Width)	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the OPA124UA is determined by strict compatibility across the following electrical and mechanical parameters:

Mechanical Compatibility: All substitute parts must use the 8-SOIC (0.154", 3.90mm Width) surface mount package to ensure direct PCB footprint compatibility without layout redesign.

Electrical Compatibility: Substitute parts must operate within the OPA124UA supply voltage range of 10V to 36V minimum and maximum specifications. The input bias current, input offset voltage, slew rate, and gain bandwidth product define the functional performance envelope. Output current capability and supply current consumption must be evaluated against circuit requirements.

Regulatory Compliance: All substitute parts must maintain ROHS3 compliance and REACH unaffected status to satisfy environmental and regulatory requirements equivalent to the original component.

The substitute parts identified—OPA145ID, AD825ARZ, AD825ARZ-REEL, and AD825ARZ-REEL7—share the 8-SOIC package footprint and operate within compatible supply voltage ranges. These parts are active products with current manufacturing status, ensuring long-term availability compared to the obsolete OPA124UA.

Parameter Comparison

Parameter	OPA124UA	OPA145ID	AD825ARZ	AD825ARZ-REEL	AD825ARZ-REEL7	Unit
Manufacturer	Texas Instruments	Texas Instruments	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.	—
Amplifier Type	General Purpose	J-FET	J-FET	J-FET	J-FET	—
Number of Circuits	1	1	1	1	1	—
Slew Rate	1.6	20	140	140	140	V/µs
Gain Bandwidth Product	1.5	5.5	26	26	26	MHz
Current - Input Bias	0.5	2	15	15	15	pA
Voltage - Input Offset	150	40	1000	1000	1000	µV
Current - Supply	2.5	0.445	6.5	6.5	6.5	mA
Current - Output / Channel	10	20	50	50	50	mA
Voltage - Supply Span (Min)	10	4.5	10	10	10	V
Voltage - Supply Span (Max)	36	36	36	36	36	V
Operating Temperature	-25°C to 85°C	-40°C to 125°C	-40°C to 85°C	-40°C to 85°C	-40°C to 85°C	—
Package / Case	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	—
Product Status	Obsolete	Active	Active	Active	Active	—
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	—

Engineering Selection Recommendations

OPA145ID Selection Criteria: The OPA145ID is an active Texas Instruments product offering improved performance over the obsolete OPA124UA while maintaining manufacturer continuity. This device features rail-to-rail output capability, reduced supply current consumption (445µA versus 2.5mA), and enhanced slew rate (20V/µs versus 1.6V/µs). The OPA145ID operates at reduced minimum supply voltage (4.5V) and extended maximum operating temperature (125°C). ROHS3 compliance and REACH unaffected status are maintained. Selection of OPA145ID is appropriate for applications requiring lower power consumption and improved dynamic performance within the same package footprint.

AD825ARZ / AD825ARZ-REEL / AD825ARZ-REEL7 Selection Criteria: The AD825 series from Analog Devices Inc. represents high-performance J-FET amplifier alternatives with significantly enhanced specifications. These devices deliver 140V/µs slew rate and 26MHz gain bandwidth product, supporting higher-frequency applications. Output current capability reaches 50mA per channel. All three variants (AD825ARZ, AD825ARZ-REEL, AD825ARZ-REEL7) share identical electrical specifications and differ only in packaging format: tube, cut tape with Digi-Reel, and cut tape with Digi-Reel variant 7 respectively. ROHS3 compliance and REACH unaffected status are maintained across all variants. Selection among AD825 variants depends on procurement and assembly requirements rather than electrical performance.

Compliance and Regulatory Status: All substitute parts maintain ROHS3 compliance and REACH unaffected status, satisfying environmental and regulatory requirements. Moisture sensitivity levels vary: OPA124UA (MSL 3), OPA145ID (MSL 2), and AD825 series (MSL 1), indicating improved moisture handling characteristics in substitute options.

Frequently Asked Questions (FAQ)

Q: Can the OPA145ID directly replace the OPA124UA without circuit modification?

A: The OPA145ID shares the 8-SOIC package footprint and operates within the OPA124UA supply voltage range (10V to 36V maximum). Direct PCB footprint compatibility is established. However, the OPA145ID features rail-to-rail output capability and significantly different performance characteristics (20V/µs slew rate, 5.5MHz gain bandwidth product, 40µV input offset voltage). Circuit validation is required to confirm functional equivalence for specific application requirements.

Q: What is the difference between AD825ARZ, AD825ARZ-REEL, and AD825ARZ-REEL7?

A: These three part numbers represent identical electrical specifications for the AD825 J-FET amplifier. The differences are packaging format only: AD825ARZ is supplied in tube packaging, AD825ARZ-REEL is supplied in cut tape with Digi-Reel format, and AD825ARZ-REEL7 is supplied in cut tape with Digi-Reel variant 7 format. Electrical performance, pin configuration, and 8-SOIC package dimensions are identical across all three variants.

Q: Does the OPA145ID operate at lower supply voltages than the OPA124UA?

A: Yes. The OPA145ID minimum supply voltage is 4.5V compared to the OPA124UA minimum of 10V. Both devices support the same maximum supply voltage of 36V. Applications operating at supply voltages below 10V require the OPA145ID or AD825 series for compatibility.

Q: Which substitute part offers the lowest power consumption?

A: The OPA145ID consumes 445µA supply current, significantly lower than the OPA124UA (2.5mA) and AD825 series (6.5mA). Selection of OPA145ID is appropriate for battery-powered or low-power applications where supply current minimization is critical.

Q: Are all substitute parts suitable for high-frequency applications?

A: The AD825 series supports the highest frequency performance with 26MHz gain bandwidth product and 140V/µs slew rate. The OPA145ID provides intermediate performance (5.5MHz gain bandwidth product, 20V/µs slew rate). The obsolete OPA124UA operates at 1.5MHz gain bandwidth product. Application frequency requirements determine appropriate substitute selection.

Q: What is the moisture sensitivity level difference between substitute parts?

A: The OPA124UA has MSL 3 (168 hours), OPA145ID has MSL 2 (1 year), and AD825 series has MSL 1 (unlimited). Lower MSL ratings indicate improved moisture tolerance and reduced risk of moisture-induced failures during storage and assembly processes.

Q: Can the AD825ARZ be used in applications requiring extended temperature operation?

A: The AD825ARZ operates across -40°C to 85°C temperature range, matching the OPA124UA upper limit of 85°C. The OPA145ID extends to 125°C maximum operating temperature. Applications requiring operation above 85°C require the OPA145ID; applications requiring operation below -25°C require the AD825ARZ or OPA145ID.

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