Texas Instruments LMP7731MAX/NOPB

Overview

LMP7731MAX/NOPB from Texas Instruments is a single-channel, rail-to-rail input/output precision operational amplifier optimized for low-noise, high-accuracy signal conditioning in low-voltage systems. It delivers 2.9 nV/√Hz input voltage noise at 1 kHz, 22 MHz gain bandwidth, 130 dB open-loop gain, ±1.5 nA input bias current, and operates from 1.8 V to 5.5 V - enabling high-fidelity sensor front-ends in photometric instrumentation and portable medical devices.

For engineers reviewing the LMP7731MAX/NOPB datasheet, LMP7731MAX/NOPB pinout, LMP7731MAX/NOPB application, or LMP7731MAX/NOPB equivalent, key selection considerations include its ultra-low 1/f noise corner (3 Hz), rail-to-rail output swing within 13 mV of rails (RL = 2 kΩ), CMRR of 130 dB, THD+N of 0.001% at 10 kHz, and guaranteed operation across −40°C to +125°C.

Technical Context

The LMP7731MAX/NOPB employs a proprietary bipolar input stage with integrated input bias current cancellation, achieving ±1.5 nA bias while retaining low voltage noise - a combination rare among precision amplifiers. Its 22 MHz GBW and 2.4 V/µs slew rate support stable closed-loop gains up to 100× without bandwidth collapse.

It features rail-to-rail input via dual parallel input stages and rail-to-rail output using complementary output transistors. Common-mode rejection remains ≥105 dB over 0–5 V input range, and PSRR exceeds 117 dB across 1.8–5.5 V supply, ensuring robust performance in noisy, battery-powered environments.

Key Specifications

Pinout & Package

The LMP7731MAX/NOPB is packaged in an 8-pin SOIC (SOIC-8) with standard pinout and thermal resistance of 190°C/W. This surface-mount package supports automated assembly and provides adequate power dissipation for 2.2 mA quiescent operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar precision op-amp applications.

Compared with OPA333AIDR and ADA4522-1ARZ, the LMP7731MAX/NOPB uniquely balances ultra-low 1/f noise (3 Hz corner), 22 MHz bandwidth, and bipolar-input precision - making it optimal for high-speed, low-noise sensor interfaces where chopper artifacts or bandwidth limitations are unacceptable.

Availability

LMP7731MAX/NOPB is available at Aetrix Electronics and suitable for gas analysis instruments, photometric instrumentation, and portable medical devices requiring stable component supply, extended temperature qualification, and long-term production continuity.

Supply support for LMP7731MAX/NOPB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of investment in precision amplifier design and manufacturing.

The LMP7731MAX/NOPB belongs to TI's LMP™ precision amplifier family, engineered specifically for low-noise, rail-to-rail, low-voltage signal conditioning in sensor interfaces, medical diagnostics, and portable instrumentation.

FAQ

What is the maximum supply voltage for the LMP7731MAX/NOPB?

The absolute maximum supply voltage for the LMP7731MAX/NOPB is 6.0 V, but the recommended operating range is 1.8 V to 5.5 V. Operation above 5.5 V risks permanent damage, while operation below 1.8 V may cause loss of rail-to-rail output swing and degraded AC performance. The LMP7731MAX/NOPB is fully specified and characterized across its 1.8–5.5 V range, including parameters like GBW, noise, and CMRR.

Does the LMP7731MAX/NOPB support true rail-to-rail input and output?

Yes, the LMP7731MAX/NOPB supports true rail-to-rail input (common-mode range from V− to V+) and rail-to-rail output (swing within 13 mV of either rail under 2 kΩ load). This is achieved via dual parallel input stages and complementary output transistors. The LMP7731MAX/NOPB maintains ≥105 dB CMRR across the full 0–5 V input range, confirming functional rail-to-rail behavior beyond mere specification claims.

What is the 1/f noise corner frequency of the LMP7731MAX/NOPB?

The LMP7731MAX/NOPB has a confirmed 1/f noise corner frequency of 3 Hz, measured per the datasheet (SNOSAT6E, Figure 1). This low corner enables stable DC-coupled operation in applications such as photodiode transimpedance amplifiers and precision bridge sensors, where low-frequency drift and flicker noise directly impact measurement accuracy over time.

Can the LMP7731MAX/NOPB drive capacitive loads like ADC inputs?

The LMP7731MAX/NOPB can drive moderate capacitive loads (≤100 pF) stably, but for ADC sampling capacitors (typically 10–30 pF switched), a series resistor (10–50 Ω) is recommended between LMP7731MAX/NOPB output and ADC input to isolate capacitance and prevent peaking or oscillation. The datasheet confirms stable operation with CL = 20 pF and RL = 10 kΩ, supporting typical SAR ADC interface requirements.

Is the LMP7731MAX/NOPB pin-compatible with other SOIC-8 op-amps?

No, the LMP7731MAX/NOPB uses a non-standard SOIC-8 pinout: Pins 1, 6, and 7 are NC (no connect), unlike industry-standard dual or quad op-amp layouts. Its pin assignment (1: NC, 2: −IN, 3: +IN, 4: V−, 5: OUT, 6: NC, 7: NC, 8: V+) is unique to the LMP773x family. PCB layout must follow the LMP7731MAX/NOPB-specific footprint; substitution with generic SOIC-8 op-amps requires redesign.