INA128PA Instrumentation Amplifier Equivalent & Substitute Parts

Part Overview

The INA128PA is a single-circuit instrumentation amplifier manufactured by Texas Instruments in 8-PDIP through-hole packaging. This device operates across a wide supply voltage range of 4.5V to 36V with a slew rate of 4V/µs and -3dB bandwidth of 1.3 MHz. The INA128PA is currently in Last Time Buy status, indicating discontinued production. Identifying equivalent and substitute parts is necessary to ensure design continuity and maintain supply chain reliability for applications requiring instrumentation amplification with these electrical characteristics.

Key Parameters

Parameter	INA128PA 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 85	°C
Mounting Type	Through Hole	—
Package / Case	8-DIP (0.300", 7.62mm)	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the INA128PA is determined by strict alignment of electrical and mechanical parameters. The primary substitution criteria are:

Mandatory Matching Parameters:

Amplifier Type: Instrumentation (single circuit)
Package Type: 8-DIP through-hole configuration
Supply Voltage Range: Minimum 4.5V, Maximum 36V
Operating Temperature Range: -40°C to 85°C minimum
RoHS3 Compliance

Secondary Electrical Compatibility Parameters:

Slew Rate: 4V/µs or greater
-3dB Bandwidth: 1.3 MHz or greater
Input Bias Current: 2 nA or lower
Input Offset Voltage: 25 µV or lower
Supply Current: 700 µA or lower
Output Current: 15 mA or greater

Substitute parts must maintain compatibility across all mandatory parameters. Secondary parameters define functional equivalence; parts exceeding these specifications remain compatible for direct replacement.

Parameter Comparison

Part Number	Manufacturer	Package	Slew Rate (V/µs)	Bandwidth (MHz)	Input Bias (nA)	Input Offset (µV)	Supply Current (µA)	Output Current (mA)	Supply Min (V)	Supply Max (V)	Temp Range (°C)	Status
INA128PA	Texas Instruments	8-DIP	4	1.3	2	25	700	15	4.5	36	-40 to 85	Last Time Buy
INA128UA/2K5	Texas Instruments	8-SOIC	4	1.3	2	25	700	15	4.5	36	-40 to 125	Active
AD620ANZ	Analog Devices Inc.	8-DIP	1.2	1	0.5	30	900	18	4.6	36	-40 to 85	Active
AD620BNZ	Analog Devices Inc.	8-DIP	1.2	1	0.5	15	900	18	4.6	36	-40 to 85	Active
AD621ANZ	Analog Devices Inc.	8-DIP	1.2	0.8	0.5	75	900	18	4.6	36	-40 to 85	Active
AD621BNZ	Analog Devices Inc.	8-DIP	1.2	0.8	0.5	50	900	18	4.6	36	-40 to 85	Active
AD622ANZ	Analog Devices Inc.	8-DIP	1.2	1	2	60	900	18	5.2	36	-40 to 85	Active
AMP02EPZ	Analog Devices Inc.	8-DIP	6	1.2	2	20	5000	32	9	36	-40 to 85	Active
AMP02FPZ	Analog Devices Inc.	8-DIP	6	1.2	4	40	5000	32	9	36	-40 to 85	Active
LT1167AIN8#PBF	Analog Devices Inc.	8-DIP	1.2	1	0.05	15	900	27	4.6	36	-40 to 85	Active
LT1167CN8#PBF	Analog Devices Inc.	8-DIP	1.2	1	0.08	20	900	—	4.6	36	0 to 70	Active

Engineering Selection Recommendations

Primary Substitute (Electrical Equivalence with Package Variation):

INA128UA/2K5 is the direct electrical equivalent manufactured by Texas Instruments. It maintains identical electrical specifications (4V/µs slew rate, 1.3 MHz bandwidth, 2 nA input bias, 25 µV input offset) and supply voltage range. The device differs only in package format (8-SOIC surface mount versus 8-DIP through hole) and extended operating temperature range (-40°C to 125°C versus -40°C to 85°C). Selection of this part requires PCB redesign for surface-mount implementation.

Secondary Substitutes (Functional Compatibility with Parameter Trade-offs):

AD620ANZ and AD620BNZ are active instrumentation amplifiers in 8-DIP through-hole packaging with identical supply voltage range and operating temperature. These parts exhibit lower slew rate (1.2V/µs versus 4V/µs) and reduced bandwidth (1 MHz versus 1.3 MHz). Input bias current is superior (0.5 nA versus 2 nA). Supply current is higher (900 µA versus 700 µA). These devices are suitable for applications where reduced slew rate and bandwidth are acceptable.

AD621ANZ and AD621BNZ operate within the same supply and temperature specifications but feature 800 kHz bandwidth and higher input offset voltage (50-75 µV versus 25 µV). These parts are applicable to lower-bandwidth instrumentation requirements.

AD622ANZ maintains 1 MHz bandwidth and 2 nA input bias current matching the INA128PA. Minimum supply voltage is 5.2V (versus 4.5V), restricting use in lower-voltage applications. Supply current is 900 µA.

AMP02EPZ and AMP02FPZ provide superior slew rate (6V/µs) and output current (32 mA) in 8-DIP packaging. Minimum supply voltage requirement is 9V, incompatible with 4.5V supply applications. Supply current is significantly higher (5 mA). These parts are suitable only for applications with 9V minimum supply availability.

LT1167AIN8#PBF offers exceptional input bias current (50 pA) and input offset voltage (15 µV) with 1 MHz bandwidth in 8-DIP packaging. Slew rate is reduced to 1.2V/µs. This part is suitable for precision measurement applications where input bias and offset specifications are critical.

LT1167CN8#PBF operates within commercial temperature range (0°C to 70°C), restricting use in extended industrial temperature applications. This part is not recommended for -40°C to 85°C operating requirements.

Compliance Status:

All substitute parts listed maintain ROHS3 compliance and REACH unaffected status, matching the INA128PA regulatory requirements.

Frequently Asked Questions (FAQ)

Q: Can INA128UA/2K5 replace INA128PA in existing through-hole PCB designs?

A: No. INA128UA/2K5 uses 8-SOIC surface-mount packaging (0.154" width) versus INA128PA 8-DIP through-hole (0.300" width). PCB redesign is required. Electrical specifications are identical.

Q: What is the primary limitation of AD620ANZ and AD620BNZ as substitutes?

A: Slew rate is reduced from 4V/µs to 1.2V/µs, and bandwidth decreases from 1.3 MHz to 1 MHz. These devices are suitable only for applications where lower slew rate and bandwidth are acceptable. Supply current increases from 700 µA to 900 µA.

Q: Can AMP02EPZ be used in 4.5V supply applications?

A: No. AMP02EPZ requires minimum 9V supply voltage. It is incompatible with 4.5V to 36V supply range applications. Additionally, supply current is 5 mA versus 700 µA for INA128PA.

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

A: LT1167AIN8#PBF provides 50 pA input bias current, significantly superior to INA128PA (2 nA). Input offset voltage is also improved (15 µV versus 25 µV). Slew rate is reduced to 1.2V/µs.

Q: Is LT1167CN8#PBF suitable for industrial temperature range applications?

A: No. LT1167CN8#PBF operates within 0°C to 70°C commercial temperature range. INA128PA operates -40°C to 85°C. LT1167CN8#PBF does not meet extended industrial temperature requirements.

Q: What is the key difference between AD621ANZ and AD621BNZ?

A: Both operate at 800 kHz bandwidth with 1.2V/µs slew rate in 8-DIP packaging. AD621ANZ specifies 75 µV input offset voltage; AD621BNZ specifies 50 µV. Both exceed INA128PA input offset specification (25 µV).

Q: Can multiple substitute parts be used interchangeably in the same application?

A: No. Each substitute exhibits different electrical characteristics. Selection must be based on specific application requirements for slew rate, bandwidth, input bias current, input offset voltage, and supply voltage range. Verify all parameters against design specifications before implementation.

Q: What is the inventory status of substitute parts?

A: INA128UA/2K5 has highest availability (35,400 pcs). AD620ANZ (29,249 pcs) and AMP02FPZ (2,958 pcs) maintain substantial inventory. LT1167AIN8#PBF (1,105 pcs) and AMP02EPZ (1,295 pcs) have limited availability. Verify current stock before design commitment.

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