Texas Instruments Amplifiers: Op Amps, Comparators & INAs

Texas Instruments amplifiers cover six working sub-families: operational amplifiers (op amps), comparators, instrumentation amplifiers, current-sense amplifiers, programmable-gain amplifiers and buffers. If you are choosing a TI op amp, the part number already tells you the lineage — OPA from Burr-Brown, TLV and TLC from TI’s CMOS lines, LM and LMV from National Semiconductor, INA for instrumentation and current sensing.

This guide breaks the families apart, puts real flagship parts side by side with their headline specs, and covers the layout and assembly details that decide whether an amplifier actually hits its datasheet numbers on your board.

• Op amps are the workhorse: precision, low-noise, high-speed and low-power variants for almost any analog stage.
• Current-sense amps (INA) measure current across a shunt, often at high common-mode voltage — INA240 handles -4 V to 80 V, INA241A reaches 110 V.
• Comparators are not op amps. Using an op amp as a comparator causes slow, oscillating outputs.
• Real precision is set by layout, not just the chip: flux residue across a high-impedance node will swamp a 5 microvolt offset.

What TI Amplifiers Are and How the Families Break Down

An operational amplifier is a high-gain differential voltage amplifier you tame with feedback to build gain stages, filters, buffers and converters. TI sells thousands of them, sorted by what they optimise: DC precision (low offset and drift), AC performance (bandwidth and slew rate), noise, or supply current.

Instrumentation amplifiers add a matched, gain-set differential front end for small signals riding on large common-mode voltages. Current-sense amplifiers are a specialised INA tuned to sit across a shunt resistor. Comparators look like op amps but are built to slam their output between rails as fast as possible, with no feedback. Programmable-gain amplifiers (PGAs) let firmware change gain on the fly, and buffers provide unity-gain isolation.

TI Op Amp Selection: Precision vs. Speed vs. Power

There is no single best TI op amp; there is the right one for your error budget. The table compares four flagship parts plus a classic, using typical datasheet figures.

TI op amp	Optimised for	Key specs	Use it when
OPA192	36 V precision	±5 µV offset, 10 MHz GBW, 20 V/µs, ±65 mA out	High-voltage industrial sensing and ADC front ends
OPA827	Low-noise JFET	150 µV max offset, 22 MHz, 28 V/µs, 3 pA bias	Photodiode/transimpedance and 16–18-bit front ends
OPA1656	Audio fidelity	2.9 nV/√Hz noise, −129 dB THD at 20 kHz, 100 mA out	Pro-audio and low-distortion signal paths
TLV9001	Cost and size	Low cost, rail-to-rail, tiny SC70/SOT package	High-volume general-purpose buffering
LM358	Legacy general	Dual, single-supply, very low cost	Non-critical level shifting and comparison

A counterintuitive point on rail-to-rail outputs: “rail-to-rail” is a no-load or light-load spec. Under real load, the output still saturates tens to a few hundred millivolts short of each rail, which quietly clips a signal you assumed had full swing. Size the supply and the load with the headroom curve, not the marketing line.

TI Current-Sense Amplifiers for Power and Motor Control

When you need to measure current across a shunt — for battery monitoring, motor phase current or supply protection — a dedicated current-sense amplifier beats a discrete op amp because it is trimmed for the job and tolerates high common-mode voltage.

Part	Common-mode range	Notable feature
INA240	−4 V to 80 V	Enhanced PWM rejection for in-line motor phase sensing
INA241A	−5 V to 110 V	Ultra-precise, bidirectional, enhanced PWM rejection
INA226	0 V to 36 V	16-bit, I²C digital power/voltage/current monitor with alert
INA181	−4 V to 26 V	350 kHz bandwidth, low-cost single-supply sensing

The PWM-rejection feature on parts like INA240 matters more than it sounds. In a motor drive, the shunt sits in a node that swings the full DC-bus voltage at the PWM frequency. A generic amplifier passes that switching edge straight into your reading; the INA240’s common-mode rejection holds up through the transient so the current sample is usable. This category is closely tied to TI motor drivers and to Texas Instruments sensors for system-level current and temperature monitoring.

Comparators vs. Op Amps: When to Use a TLV3xxx

Reaching for a spare op amp as a comparator is one of the most common analog mistakes. An op amp is internally compensated for stable closed-loop operation; driven open-loop to the rails it responds slowly, may oscillate near the threshold, and can latch. A dedicated comparator such as the TLV3201 or the nanopower TLV3691 is built to switch cleanly with defined propagation delay and, in many parts, built-in hysteresis.

Use an op amp when you have feedback and want a linear output. Use a comparator when you want a clean digital decision from an analog threshold. They are not interchangeable, even though the symbol looks the same.

Amplifier Layout and Assembly: What Decides Real-World Performance

A 5 microvolt offset op amp is meaningless if the board adds 50 microvolts of error. Three manufacturing factors dominate:

1. Cleanliness on high-impedance nodes. Ionic flux residue creates leakage paths that inject error and drift. For transimpedance and electrometer stages, specify a no-clean process verified to J-STD-001 cleanliness requirements, and add a guard ring around the summing node.
2. Footprint accuracy. Small SOT-23, SC70 and X2SON amplifier packages release paste poorly if the land pattern is not built to IPC-7351, which shows up as tombstoning or weak heel fillets graded against IPC-A-610.
3. Decoupling and layout. Place the bypass capacitor at the supply pin and keep the feedback loop tight; a long feedback trace turns a stable amplifier into an oscillator regardless of the silicon.

A medical front-end client once chased a slow millivolt-level drift for weeks. The op amp was fine; the cause was flux residue bridging a gigaohm photodiode node. Switching to a verified no-clean process and adding a guard ring removed the drift entirely. The lesson: at high impedance, the assembly process is part of the circuit. Precision amplifiers most often pair with Texas Instruments data converters as ADC drivers, and the op amp’s settling time, not the ADC, frequently sets the achievable sample rate.

Common TI Amplifier Selection Mistakes

1. Picking by GBW alone and ignoring slew rate, which limits large-signal bandwidth.
2. Assuming rail-to-rail output swing under load.
3. Using an op amp where a comparator belongs.
4. Choosing a zero-drift (chopper) amp for an audio path, where its switching artifacts add noise.
5. Treating layout and cleanliness as someone else’s problem on a precision node.

Frequently Asked Questions About TI Amplifiers

What is the difference between OPA, TLV and LM op amps?

OPA parts trace to the Burr-Brown precision line and target the highest DC and AC performance. TLV parts are TI’s low-voltage CMOS amplifiers optimised for cost, size and low power. LM parts originated at National Semiconductor and include many legacy industry-standard amplifiers.

Which TI op amp has the lowest noise?

It depends on the band. For audio and wideband work, the OPA1656 reaches about 2.9 nV/√Hz. For DC precision with low 0.1–10 Hz noise, JFET parts like the OPA827 lead. Match the noise spec to your signal bandwidth rather than chasing one headline number.

Can I use a TI op amp as a comparator?

You can, but you usually should not. Op amps respond slowly and may oscillate when driven open-loop. A dedicated comparator such as the TLV3201 switches faster and more reliably and often includes hysteresis.

What is a current-sense amplifier used for?

It measures the small voltage across a shunt resistor to report current, often at high common-mode voltage. TI INA parts like the INA240 add PWM rejection so they work in motor drives where the shunt node swings with the switching waveform.

Why does my precision amplifier drift on the assembled board?

The most common cause is contamination on a high-impedance node. Flux residue forms leakage paths that add offset and drift. A verified clean or no-clean process and a guard ring around sensitive nodes usually resolve it.

Spec Your TI Amplifier, Then Build It Right

Choose the amplifier family from your error budget, confirm the package against your assembly process, and when the design is set, send your Gerber and BOM for a DFM review so the cleanliness and footprint details that protect precision are handled before the first build. Return to the Texas Instruments component hub to map the rest of your signal chain.