INA116PA - 3fA Ultra Low Bias Current In-Amp | TI
MPN: INA116PA β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $35.05 | $35.05 |
| 10 | $33.3 | $333.00 |
| 100 | $31.55 | $3,155.00 |
| 500 | $29.79 | $14,895.00 |
| 1,000 | $28.04 | $28,040.00 |
Drop-in alternatives for INA116PA β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
INA116PAG4
β Drop-Inπ Reference alternative (not in catalog)
INA116PAG4
β Drop-Inπ Reference alternative (not in catalog)
INA116PA Maximum Ratings & Electrical Characteristics
| Amplifier Type | Instrumentation Amplifier |
| Number of Channels | 1 |
| Input Bias Current (typ) | 3 fA at 25C |
| Input Bias Current (at 85C) | 25 fA |
| Input Offset Voltage (max) | 2 mV |
| Gain Range | 1 V/V to 1000 V/V |
| CMRR (min) | 86 dB |
| Input Noise Density at 1 kHz | 28 nV/sqrt(Hz) |
| Quiescent Current | 1 mA |
| Supply Voltage Range (single) | 9 V to 36 V |
| Supply Voltage Range (dual) | +/-4.5 V to +/-18 V |
| Input Technology | Difet FET with buffered guard drive |
| Input Overvoltage Protection | Yes |
| Operating Temperature Range | -40C to +85C |
| Package | 16-PDIP (N) |
| Mounting Type | Through Hole |
INA116PA 16-pdip (n) Pin Configuration Guide
Complete pinout information for INA116PA (16-pdip (n) package). This analog component features input, output, and power supply pins. Refer to the manufacturer datasheet for offset null, compensation, and enable pin configurations. Ideal for signal conditioning and amplifier circuits.
No detailed pinout data available for INA116PA.
Refer to the datasheet for full pin configuration.
Safe Operating Area (SOA) & Thermal Characteristics
No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.
Typical Applications
INA116PA is suitable for 6 applications: Photodiode Current Measurement, pH and Chemical Sensor Interfaces, Ionization Chamber and Radiation Detection, Precision Transducer Signal Conditioning, Medical and Biomedical Instrumentation, Mass Spectrometry and Vacuum Gauge Readout.
Photodiode Current Measurement
The INA116PA is exceptionally well suited to photodiode front ends because its 3 fA typical input bias current at 25C contributes essentially zero error relative to nanoampere or picoampere photocurrents, preserving measurement linearity down to the detection floor. In a typical circuit, the photodiode feeds the inverting input, the amplifier output drives a transimpedance or gain network, and the buffered guard drive pin is routed as a guard ring around the summing node to bootstrap away PCB leakage. The 1 to 1000 V/V gain range lets one design cover optical power meters, chromatography detectors, and fluorescence readers. Unlike discrete FET front ends, the monolithic three-op-amp topology maintains 86 dB minimum CMRR without hand matching, and the 28 nV/sqrt(Hz) input noise at 1 kHz keeps small-signal resolution high across the -40C to +85C industrial range.
Recommended
pH and Chemical Sensor Interfaces
Glass pH electrodes and similar electrochemical sensors present source impedances of hundreds of megaohms or more, a regime where the INA116PA's femtoampere input bias current is decisive: at 3 fA typical, bias-current error through a 1 GOhm electrode is microvolts or less, whereas a conventional in-amp drawing picoamperes would introduce hundreds of microvolts of error and electrode polarization. The differential input rejects ground-path common-mode noise in wet or industrial environments, and the 86 dB minimum CMRR suppresses mains interference. The buffered guard drive output is connected to a driven shield on the electrode cable, eliminating shield leakage and capacitance effects that would otherwise slow response and add noise. With gain set from 1 to 1000 V/V via one resistor and a +/-4.5 V to +/-18 V supply range matching standard analog rails, the part integrates cleanly into laboratory analyzers and environmental monitoring transmitters.
Recommended
Ionization Chamber and Radiation Detection
Ionization chambers used in radiation monitoring, smoke detection, and beam instrumentation produce currents in the picoampere range at extremely high source impedance, exactly matching the INA116PA design envelope. The Difet input stage with special guarding techniques yields 3 fA typical bias current at 25C and still only 25 fA at 85C, so chamber background currents are not corrupted by amplifier leakage even in elevated-temperature installations. The two buffered guard drive pins are used to guard both input nodes and chamber feedthroughs, a technique described in the TI datasheet application section, suppressing surface leakage that dominates fA-level systems. Input overvoltage protection guards against transient events, and the 1 mA quiescent current permits battery-powered portable survey instruments. The PDIP-16 through-hole package also supports hand rework and prototyping common in nuclear instrumentation development.
Recommended
Precision Transducer Signal Conditioning
Bridge and differential transducers - load cells, pressure sensors, thermistor bridges - benefit from the INA116PA's differential topology, 2 mV maximum input offset, and gain programmability from 1 V/V to 1000 V/V with a single resistor. While bias-current headroom exceeds most bridge requirements, the femtoampere inputs allow very large bridge resistances (10 MOhm and above) without loading error, enabling low-power sensor designs where bridge current must be minimized. The 86 dB minimum CMRR rejects ground differentials in industrial wiring, and the 28 nV/sqrt(Hz) noise at 1 kHz supports resolution of small bridge outputs over 10 kHz measurement bandwidths. Supply operation from 9 V to 36 V total covers +/-12 V and +/-15 V industrial analog rails directly. Setting gain close to the sensor full-scale requirement with a precision resistor yields best offset-drift performance per the TI datasheet guidance.
Recommended
Medical and Biomedical Instrumentation
Biopotential and biosensor acquisition - impedance plethysmography, high-impedance microelectrode buffers, ion-selective electrode arrays - requires amplifiers that do not load the biological source. The INA116PA's 3 fA input bias current ensures negligible electrode polarization and DC offset artifacts even through glass microelectrodes of 100 MOhm impedance, and its differential three-op-amp architecture with 86 dB minimum CMRR rejects mains common-mode interference inherent in clinical environments. Guard drive pins are connected to driven shields on electrode cables, reducing cable leakage and preserving signal bandwidth, a critical technique at fA input levels per the TI datasheet. Operation from +/-4.5 V supplies suits battery-powered portable medical devices, while the -40C to +85C rating covers sterilization-adjacent environments. Gain from 1 to 1000 V/V lets one amplifier design serve multiple electrode types across a product family.
Recommended
Mass Spectrometry and Vacuum Gauge Readout
Faraday cup collectors, residual gas analyzer detectors, and hot/cold cathode vacuum gauge electrometers output femtoampere-to-picoampere currents at very high impedance, making the INA116PA a natural front-end choice. Its 3 fA typical input bias current approaches the detector floor itself, and the buffered guard pins allow complete guarding of the collector feedthrough and cabling, which the TI datasheet identifies as essential to realizing rated bias performance in system. The 28 nV/sqrt(Hz) input noise at 1 kHz and 86 dB minimum CMRR preserve dynamic range across decade-spanning pressure or ion-current measurements, with the 1 to 1000 V/V gain resistor allowing ranged autoranging designs. Input overvoltage protection withstands collector transients during filament events, and the 1 mA quiescent draw from 9 V to 36 V total supply integrates into rack-mounted instrument power schemes without thermal concerns.
Recommended
Recommended Products Summary
Engineering reference data for INA116PA β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | INA116PAG4 | INA116UA |
|---|---|---|---|
| Package | 16-PDIP (N) | 16-PDIP (N) - same | 16-SOIC (not drop-in) |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments |
| Input Bias Current (typ) | 3 fA at 25C | 3 fA at 25C | 3 fA at 25C |
| Input Offset Voltage (max) | 2 mV | 2 mV | 2 mV |
| Gain Range | 1 V/V to 1000 V/V | 1 V/V to 1000 V/V | 1 V/V to 1000 V/V |
| CMRR (min) | 86 dB | 86 dB | 86 dB |
| Quiescent Current | 1 mA | 1 mA | 1 mA |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C |
| Unit Price (qty 1) | $35.05 (as of 2026-09-13) | [DATA_NEEDED] | [DATA_NEEDED] |
Key Differentiators
- Femtoampere input bias current (vs INA118)
- Buffered guard drive pins (vs PGA204AP)
- Same-die drop-in continuity (vs INA116PAG4)
Design Notes
PCB leakage is the dominant error source in fA-level designs. Surround both input traces with guard rings driven from the INA116PA's buffered guard drive pins so the guards track input common-mode potential and bootstrap away surface leakage. Keep input traces as short as possible, avoid vias on input nets, and mount the amplifier on PTFE or glass-epoxy standoffs for bench electrometers. Clean flux residues thoroughly (no-clean flux can be conductive at high impedance) and consider conformal coating after cleaning to stabilize surface resistance against humidity.
Set gain with a single resistor between the gain-set pins; the resistor's temperature coefficient directly becomes gain drift, so use a 25 ppm/C or better precision part for demanding applications. Note that at high gain the first stage dominates noise while at low gain the output stage noise and the 28 nV/sqrt(Hz) input density both matter; keep source resistance balanced at the two inputs so bias-current offsets convert to common-mode rather than differential error, preserving the 86 dB minimum CMRR.
Do not route digital or switching-regulator traces near the input guard area; capacitively coupled dV/dt injects charge into fA-level nodes. Observe input overvoltage limits even though protection is provided - sustained faults beyond the specified protection range damage the Difet input stage. Finally, remember bias current roughly doubles approximately every 10C: at 85C the typical bias is 25 fA versus 3 fA at 25C, so thermal management of nearby heat sources matters in ultra-precise designs.
Compliance Information
Compliance details were not present in the provided verified web data; consult the TI.com product page for the INA116 current RoHS/REACH status. TI part numbering 'PA' (plastic DIP) historically indicates non-RoHS leaded construction for legacy devices - verify before export-controlled or EU-market designs.
