INA128PA - 130dB CMRR Low-Power INA | Texas Instruments
MPN: INA128PA ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
INA128PA Overview
An instrumentation amplifier is a specialized analog amplifier optimized for measuring low-level differential signals in the presence of large common-mode voltages. Its internal three-op-amp arrangement provides high input impedance, accurate differential gain, and strong common-mode rejection without requiring matched external resistors. INA128PA belongs to the instrumentation-amplifier hierarchy, which sits within signal-conditioning and amplifier ICs used in instrumentation, industrial control, biomedical measurement, and test equipment.
Verified features include a maximum input offset voltage of 50 µV, maximum input voltage drift of 0.5 µV/°C, maximum input bias current of 5 nA, minimum CMR of 120 dB, input protection to ±40 V, and a supply range up to ±18 V. The low quiescent current is 700 µA, making the device suitable for power-conscious precision analog systems. According to the verified TI product data, the INA128 family provides 200 kHz bandwidth at a gain of 100.
The three-op-amp internal design uses current-feedback input circuitry to preserve bandwidth as gain increases. This architecture is important when the measured signal is small and the source impedance is not negligible: the low 5 nA maximum bias current reduces loading of high-resistance sensors. The 130 dB CMRR specification helps reject common-mode voltage produced by motor systems, mains-coupled noise, or long sensor cables.
Typical uses include precision current sensing, bridge-transducer amplification, biomedical instrumentation, portable measurement, laboratory equipment, and industrial process monitoring. The part can operate from dual or single supplies as supported by the family documentation, but the exact operating modes and output-swing limits should be checked against the manufacturer datasheet before final design release.
For PCB implementation, keep the gain resistor close to the gain-setting pins and use a quiet ground return for the signal path. Input filtering, common-mode voltage limits, output settling, and supply decoupling must be evaluated for the target gain and bandwidth. Do not assume that the protected input rating removes the need for external transient protection in every system.
This page combines verified manufacturer and distributor information, package-specific identification, application guidance, and cautious replacement analysis. Values not explicitly verified in the supplied data remain marked for engineering review rather than estimated.
Drop-in alternatives for INA128PA — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with INA128PA (same form factor and footprint) — differing in Package, Gain Range, Mounting Type, Number of Circuits, Gain Setting.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
INA128P
✅ Drop-In📋 Reference alternative (not in catalog)
INA129PA
✅ Drop-In📋 Reference alternative (not in catalog)
AD620ARZ
✅ Drop-In✓ In Stock
$7.2 / Unit
View Datasheet →INA128PA Maximum Ratings & Electrical Characteristics
| Product Type | Precision instrumentation amplifier |
| Architecture | Three-op-amp instrumentation amplifier |
| Number of Circuits | 1 circuit |
| Package | 8-pin PDIP |
| Common-Mode Rejection Ratio | 130 dB |
| Minimum Common-Mode Rejection | 120 dB |
| Quiescent Current | 700 µA |
| Maximum Input Offset Voltage | 50 µV |
| Maximum Input Voltage Drift | 0.5 µV/°C |
| Maximum Input Bias Current | 5 nA |
| Input Protection | ±40 V |
| Supply Range | Up to ±18 V |
| Gain Range | 1 to 10,000 |
| Gain Setting | Single external resistor |
| Bandwidth at Gain 100 | 200 kHz |
| Green Product | Yes |
| Restricted Substances | No Sb/Br |
| Operating Temperature | -40°C to +85°C |
| Mounting Type | Through-hole |
INA128PA Pin Configuration
| Pin 1 | NC — Not connected; exact pin function must be confirmed from the manufacturer datasheet |
| Pin 2 | IN- — Inverting input |
| Pin 3 | IN+ — Non-inverting input |
| Pin 4 | V- — Negative supply |
| Pin 5 | RG — Gain-setting resistor connection |
| Pin 6 | OUT — Output |
| Pin 7 | V+ — Positive supply |
| Pin 8 | REF — Reference input |
Typical Applications
INA128PA is suitable for 6 applications: Precision Bridge Measurement, Industrial Current Sensing, Biomedical Sensor Signal Conditioning, Portable Test and Measurement, Load Cell and Pressure Transducer Interface, Laboratory Instrumentation.
Precision Bridge Measurement
INA128PA fits Wheatstone-bridge signal conditioning when small millivolt-level differential signals must be measured beside a much larger common-mode voltage. Its verified 50 µV maximum offset voltage, 0.5 µV/°C maximum drift, and 130 dB CMRR help preserve measurement accuracy as temperature and common-mode conditions change. The 5 nA maximum input bias current also limits error when bridge arms have high effective resistance. Configure the gain with one external resistor and use the verified 200 kHz bandwidth at gain 100 as an initial design reference. Check the bridge excitation, input common-mode range, output swing, and settling time in the TI datasheet before production.
Recommended
Industrial Current Sensing
INA128PA is appropriate for low-level current-shunt monitoring where the measured differential voltage is small and the surrounding environment contains switching or motor noise. The verified 130 dB CMRR specification helps reject common-mode voltage on shunt wiring, while the three-op-amp architecture provides accurate differential gain without matched external resistor networks. Its 5 nA maximum input bias current supports higher shunt and sensing impedances. Use short, symmetric shunt connections and verify the input protection, common-mode range, bandwidth, and output swing for the actual shunt and power-supply conditions.
Recommended
Biomedical Sensor Signal Conditioning
INA128PA can be used for low-amplitude biomedical sensor front ends when low offset, low drift, and high input impedance are important. The verified 50 µV offset and 0.5 µV/°C drift help reduce measurement error in temperature-sensitive systems, while 5 nA maximum bias current limits loading of high-source-impedance electrodes or resistive sensors. Its 700 µA quiescent current supports power-constrained instrumentation. A medical design still requires isolation, patient-protection, leakage-current, noise, and regulatory analysis that are not established by the supplied component data.
Recommended
Portable Test and Measurement
INA128PA suits portable measurement equipment that combines sensor excitation, signal conditioning, and data conversion. The low 700 µA quiescent current can help preserve battery life, while high CMRR reduces the impact of common-mode voltage in handheld probes and long cables. The gain range of 1 to 10,000 lets one device support several input scales, but bandwidth decreases as gain increases. Validate input protection, settling behavior, output range, and grounding because a portable enclosure may introduce ESD, cable transients, and ground-offset concerns.
Recommended
Load Cell and Pressure Transducer Interface
INA128PA is well suited to load-cell and pressure-transducer interfaces because these sensors commonly produce small differential outputs while sharing a substantial excitation common mode. Its verified 130 dB CMRR helps suppress common-mode variation, and the low offset and drift specifications support stable zero and scale-factor behavior. The single-resistor gain configuration simplifies analog front-end construction. Designers should still account for sensor excitation noise, input filtering, cable capacitance, output settling, and the available bandwidth at the selected gain before release.
Recommended
Laboratory Instrumentation
INA128PA can serve as the analog input stage of laboratory instrumentation, including programmable sources, measurement modules, and sensor interfaces. The combination of 700 µA quiescent current, 200 kHz bandwidth at gain 100, and low offset supports a useful compromise between power consumption and response speed. High CMRR is particularly useful when the input is connected to external fixtures or floating sources. For bench equipment, provide clean grounding, stable reference connections, adequate supply bypassing, and input filtering; verify the exact output and input limits from the TI datasheet.
Recommended
Recommended Products Summary
Engineering reference data for INA128PA — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | INA128P | INA129PA | AD620 |
|---|---|---|---|---|
| Package | 8-pin PDIP | 8-pin PDIP | 8-pin PDIP | 8-pin PDIP |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Analog Devices |
Key Differentiators
- High verified common-mode rejection (vs INA128P)
- Low-power signal conditioning (vs INA129PA)
- Precision offset and drift (vs AD620)
- Through-hole package fit (vs INA128UA)
Design Notes
Place the external gain resistor close to the INA128PA gain-setting pin and keep the differential input traces short and symmetric where practical. Long traces around high-impedance inputs can add noise and parasitic capacitance. Keep the reference connection quiet and route it away from switching nodes, motor traces, and high-current return paths. The through-hole package does not eliminate PCB-layout sensitivity; the analog signal path still requires controlled grounding.
Provide local supply bypassing close to the positive and negative supply pins, using the capacitor values and stability requirements specified in the TI datasheet. The verified 700 µA quiescent current is low, but external divider, reference, and load currents still determine total power. Verify the supply voltage, input common-mode range, and output swing before fixing the operating point. Do not use the ±40 V input-protection statement as a substitute for an application-specific transient analysis.
The gain resistor tolerance directly affects gain accuracy, so use the resistor value and tolerance recommended by the manufacturer and include gain error in the system budget. Also check offset voltage, drift, input bias current, source resistance, and temperature gradients. At high gain, bandwidth and settling behavior can become limiting even though the device is specified at 200 kHz for gain 100. Confirm the actual operating gain and signal bandwidth before release.
For sensor or shunt measurements, minimize input-loop area and avoid routing sensitive input traces parallel to power-switching or motor-control paths. A grounded guard or shielding approach may be useful for high-impedance sources, but it must be validated against leakage and capacitance requirements. Check the reference pin treatment and output-filter stability against the latest manufacturer application guidance rather than copying a generic instrumentation-amplifier layout.
Compliance Information
Verified results identify a green product and no Sb/Br, but do not provide a complete RoHS, REACH, lead-free, halogen-free, or conflict-minerals declaration.
