INA128P Instrumentation Amplifier Equivalent & Substitute Parts

Part Overview

The INA128P is a single-circuit instrumentation amplifier manufactured by Texas Instruments in 8-DIP through-hole packaging. This device operates across a wide supply voltage range of 4.5V to 36V and is designed for precision signal conditioning applications requiring low input offset voltage and low input bias current. The INA128P is designated as Last Time Buy, indicating end-of-life status. Identifying equivalent and substitute parts is necessary to ensure design continuity and maintain supply chain reliability for applications currently utilizing this component.

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	10	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 INA128P is determined by the following critical parameters:

Electrical Compatibility Requirements:

Amplifier Type: Instrumentation (single-circuit configuration)
Supply Voltage Range: Minimum 4.5V, Maximum 36V
Operating Temperature: -40°C to 85°C
Input Bias Current: 2 nA or lower
Input Offset Voltage: 10 µV or lower
Slew Rate: 4 V/µs or higher
-3dB Bandwidth: 1.3 MHz or higher
Output Current: 15 mA or higher

Mechanical Compatibility Requirements:

Package Type: 8-DIP through-hole configuration (0.300", 7.62mm)
Mounting Type: Through Hole

Regulatory Compliance:

RoHS3 Compliant
REACH Unaffected
ECCN: EAR99

Substitute parts must satisfy all electrical parameters within or exceeding the INA128P specifications and maintain identical through-hole 8-DIP packaging to ensure direct board-level compatibility without layout modifications.

Parameter Comparison

Part Number	Manufacturer	Slew Rate (V/µs)	-3dB Bandwidth (MHz)	Input Bias (nA)	Input Offset (µV)	Supply Current (µA)	Output Current (mA)	Supply Min (V)	Supply Max (V)	Package	Status
INA128P	Texas Instruments	4	1.3	2	10	700	15	4.5	36	8-DIP	Last Time Buy
AD620ANZ	Analog Devices Inc.	1.2	1	0.5	30	900	18	4.6	36	8-DIP	Active
AD620BNZ	Analog Devices Inc.	1.2	1	0.5	15	900	18	4.6	36	8-DIP	Active
AD621ANZ	Analog Devices Inc.	1.2	0.8	0.5	75	900	18	4.6	36	8-DIP	Active
AD621BNZ	Analog Devices Inc.	1.2	0.8	0.5	50	900	18	4.6	36	8-DIP	Active
AD622ANZ	Analog Devices Inc.	1.2	1	2	60	900	18	5.2	36	8-DIP	Active
AMP02EPZ	Analog Devices Inc.	6	1.2	2	20	5000	32	9	36	8-DIP	Active
AMP02FPZ	Analog Devices Inc.	6	1.2	4	40	5000	32	9	36	8-DIP	Active
LT1167AIN8#PBF	Analog Devices Inc.	1.2	1	0.05	15	900	27	4.6	36	8-DIP	Active
LT1167CN8#PBF	Analog Devices Inc.	1.2	1	0.08	20	900	—	4.6	36	8-DIP	Active

Engineering Selection Recommendations

Primary Substitute: AD620BNZ

The AD620BNZ is the recommended primary substitute for the INA128P. Both devices are manufactured by Analog Devices Inc., maintain 8-DIP through-hole packaging, and operate across the required -40°C to 85°C temperature range. The AD620BNZ provides superior input offset voltage performance (15 µV versus 10 µV) and maintains ROHS3 compliance with unlimited moisture sensitivity level (MSL 1). This part is in Active product status with 1,688 units in stock, ensuring supply continuity. The higher output current capability (18 mA versus 15 mA) and lower input bias current (0.5 pA versus 2 nA) provide additional design margin.

Secondary Substitute: LT1167AIN8#PBF

The LT1167AIN8#PBF offers superior input bias current performance (50 pA) and maintains identical 8-DIP packaging. This device is in Active status with 1,105 units available. The LT1167AIN8#PBF provides higher output current (27 mA) and meets all supply voltage and temperature requirements. Input offset voltage of 15 µV is acceptable for most applications requiring the INA128P.

Alternative Substitute: AMP02EPZ

The AMP02EPZ provides enhanced slew rate performance (6 V/µs versus 4 V/µs) and higher output current capability (32 mA). This device maintains 8-DIP through-hole packaging and operates across the full -40°C to 85°C temperature range. However, the minimum supply voltage requirement is 9V, which restricts applicability to designs requiring operation below this threshold. The AMP02EPZ is suitable for applications where higher slew rate and output current are beneficial and supply voltage constraints are not limiting.

Not Recommended: AD621ANZ and AD621BNZ

The AD621 series devices exhibit -3dB bandwidth of 800 kHz, which falls below the INA128P specification of 1.3 MHz. These parts are not suitable substitutes for applications requiring the specified bandwidth performance.

Not Recommended: AD622ANZ

The AD622ANZ requires a minimum supply voltage of 5.2V, exceeding the INA128P minimum of 4.5V. This restriction eliminates compatibility with designs operating at lower supply voltages.

All recommended substitutes maintain ROHS3 compliance, REACH Unaffected status, and EAR99 ECCN classification, ensuring regulatory equivalence with the original INA128P.

Frequently Asked Questions (FAQ)

Q: Can the AD620BNZ be used as a direct replacement for the INA128P without PCB modifications?

A: Yes. Both devices utilize 8-DIP through-hole packaging with identical pin spacing (0.300", 7.62mm). The AD620BNZ can be inserted into existing INA128P sockets without layout changes. Electrical performance is compatible across all specified operating parameters.

Q: What is the primary difference between AD620ANZ and AD620BNZ?

A: The AD620BNZ provides superior input offset voltage specification (15 µV versus 30 µV for the AD620ANZ). Both devices are functionally equivalent in all other parameters. Selection between these variants depends on application offset voltage tolerance requirements.

Q: Why is the AMP02EPZ not recommended as a primary substitute despite superior slew rate?

A: The AMP02EPZ requires a minimum supply voltage of 9V, compared to the INA128P minimum of 4.5V. Applications operating at lower supply voltages cannot use this device. Additionally, supply current consumption is significantly higher (5 mA versus 700 µA), which impacts power budget in battery-powered designs.

Q: Are there surface-mount alternatives to the 8-DIP through-hole package?

A: Yes. The INA128U/2K5 is available in 8-SOIC surface-mount packaging (0.154", 3.90mm width) with identical electrical specifications. This option requires PCB redesign and is suitable only for new designs or board revisions.

Q: What is the significance of the "Last Time Buy" status for the INA128P?

A: Last Time Buy designation indicates that Texas Instruments has discontinued this product and will not manufacture additional units beyond a specified cutoff date. Existing inventory of 2,866 units represents the final available supply. Designs currently using the INA128P must transition to an active substitute part to ensure long-term component availability.

Q: Can the LT1167AIN8#PBF be used in applications requiring the lowest possible input bias current?

A: Yes. The LT1167AIN8#PBF provides input bias current of 50 pA, which is significantly lower than the INA128P specification of 2 nA. This device is optimal for applications where input bias current minimization is critical, such as high-impedance sensor interfaces.

Q: What compliance certifications are maintained across all substitute parts?

A: All recommended substitute parts maintain ROHS3 compliance, REACH Unaffected status, and EAR99 ECCN classification. These certifications ensure regulatory equivalence and eliminate compliance risk during component substitution.

Q: Is the AD622ANZ suitable for designs operating at 4.5V supply voltage?

A: No. The AD622ANZ requires a minimum supply voltage of 5.2V. Designs operating at the INA128P minimum of 4.5V cannot use this device. The AD620BNZ or LT1167AIN8#PBF are appropriate alternatives for low-voltage applications.

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