Texas Instruments LMH6550MAX/NOPB

Overview

LMH6550MAX/NOPB from Texas Instruments is a high-speed, fully differential voltage-feedback operational amplifier optimized for driving high-performance ADCs and balanced transmission lines. It delivers 400 MHz −3-dB bandwidth (V_OUT = 0.5 V_PP), 3000 V/µs slew rate, and −92/−103 dB HD2/HD3 at 5 MHz under ±5 V supply, enabling low-distortion signal conditioning in IF/RF and video-over-twisted-pair systems.

For engineers reviewing the LMH6550MAX/NOPB datasheet, LMH6550MAX/NOPB pinout, LMH6550MAX/NOPB application, or LMH6550MAX/NOPB equivalent, this page provides verified specifications, validated pin functions, confirmed SOIC-8 package mapping, real-world application context for differential AD drivers and SAW filter buffering, and two technically documented alternative parts with explicit functional and application-level differences.

Technical Context

The LMH6550MAX/NOPB implements a three-channel architecture: two high-speed differential signal paths (V+ and V−) operating as inverting-mode amplifiers, plus an independent common-mode feedback loop that senses output average voltage and forces it to match the VCM pin reference-enabling precise single-ended-to-differential conversion. Its voltage-feedback topology uses external gain-setting resistors (e.g., RF = RG = 365 Ω) for flexible gain configuration up to 15 V/V.

This FDA integrates internal averaging resistors for common-mode sensing, a dedicated VCM error amplifier with 210 MHz small-signal bandwidth (±5 V), and an enable-controlled shutdown mode with 10 ns enable/disable timing. The core amplifier achieves >70 dB open-loop gain and 74–90 dB PSRR, supporting stable operation with split (±5 V) or single (5 V) supplies across −40°C to +85°C.

Key Specifications

Pinout & Package

LMH6550MAX/NOPB is housed in an 8-pin SOIC package (4.90 mm × 3.91 mm body size), optimized for thermal performance (R_θJA = 150 °C/W) and PCB layout symmetry in high-frequency differential routing.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar differential amplifier applications.

Compared with THS4561DR and ADA4940-1ARZ, LMH6550MAX/NOPB uniquely balances ultra-wide bandwidth, high output current, and integrated enable functionality-making it the only option among the three capable of driving both high-speed ADCs and 100-m twisted-pair cables without external support circuitry.

Availability

LMH6550MAX/NOPB is available at Aetrix Electronics and suitable for high-speed data acquisition, video transmission, and IF/RF signal conditioning requiring stable component supply across industrial, test & measurement, and communications equipment lifecycles.

Supply support for LMH6550MAX/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 delivering analog and embedded processing solutions, with over 50 years of innovation in high-speed amplifiers and data converter interface ICs.

The LMH6550MAX/NOPB belongs to TI's high-speed differential amplifier product line, engineered specifically for low-distortion, wide-bandwidth signal conditioning in ADC driver, communications infrastructure, and video system applications.

FAQ

What is the maximum differential output voltage swing for LMH6550MAX/NOPB at ±5 V supply?

The LMH6550MAX/NOPB delivers up to 7.8 V_PP differential output voltage swing at ±5 V supply and 25°C, with 7.18 V_PP maintained across the full −40°C to +85°C operating temperature range. This swing is achieved with RL = 500 Ω and RF = RG = 365 Ω, supporting full-scale drive into high-impedance ADC inputs or transformer-coupled loads. The LMH6550MAX/NOPB maintains linear operation up to ±75 mA output current before clipping.

How does the VCM pin function in LMH6550MAX/NOPB, and what happens if left unconnected?

The VCM pin on the LMH6550MAX/NOPB sets the output common-mode voltage via an internal error amplifier that compares the pin voltage to the average of +OUT and −OUT. If left unconnected, internal 50 kΩ resistors bias VCM to mid-supply (0 V with ±5 V supplies), establishing the default output common-mode level. However, TI strongly recommends bypassing VCM to ground with a 0.1 µF ceramic capacitor-even when unused-to prevent noise coupling that degrades dynamic range and balance error. The LMH6550MAX/NOPB will operate with floating VCM, but performance is not guaranteed per datasheet specs.

Can LMH6550MAX/NOPB operate from a single 5 V supply, and what are the key constraints?

Yes, the LMH6550MAX/NOPB supports single 5 V supply operation with V+ = 5 V and V− tied to GND. Key constraints include reduced small-signal bandwidth (350 MHz vs. 400 MHz), lower output swing (2.8 V_PP differential), and shifted input common-mode range (0.4 V to 3.2 V). The VCM pin must be biased to 2.5 V for optimal performance, and the enable threshold shifts to 2.0 V (high) / 1.5 V (low). All LMH6550MAX/NOPB electrical characteristics-including HD2/HD3 and settling time-are specified under both ±5 V and 5 V conditions in the official datasheet.

What external components are mandatory for stable operation of LMH6550MAX/NOPB?

Mandatory external components for stable LMH6550MAX/NOPB operation include: (1) 0.01 µF and 0.1 µF ceramic bypass capacitors placed within 3 mm of V+ and V− pins; (2) 0.1 µF ceramic capacitor from VCM to ground; (3) matched RF and RG gain-setting resistors (e.g., 365 Ω for unity gain); and (4) optional RO series resistors (e.g., 13–40 Ω) between outputs and capacitive loads like ADC inputs to suppress peaking. TI specifies no minimum external components beyond these-no compensation capacitors or feedback networks are required for basic unity-gain stable operation.

Is LMH6550MAX/NOPB pin-compatible with other Texas Instruments differential amplifiers like LMH6552 or THS4521?

No, LMH6550MAX/NOPB is not pin-compatible with LMH6552 or THS4521. LMH6550MAX/NOPB uses an 8-pin SOIC package with EN, VCM, IN−, IN+, +OUT, −OUT, V+, and V− pins arranged in standard D-package order. LMH6552 uses a 16-pin SOIC with different pinout (including separate VOCM, OUTP, OUTN, INP, INN, and power pins), while THS4521 uses an 8-pin SOIC but assigns VCM to pin 1 and lacks an enable pin-making direct PCB replacement impossible without layout revision. The LMH6550MAX/NOPB pinout is unique to its family and verified in TI's SNOSAK0I datasheet Figure 6.