Texas Instruments LMH6550MM/NOPB

Overview

LMH6550MM/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 LMH6550MM/NOPB datasheet, LMH6550MM/NOPB pinout, LMH6550MM/NOPB application, or LMH6550MM/NOPB equivalent, this page provides verified functional identity, validated VSSOP-8 pin mapping, confirmed differential line driver and single-ended-to-differential converter use cases, and two technically documented alternative parts with explicit gain-setting and common-mode control differences.

Technical Context

The LMH6550MM/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 RF/RG resistors for gain setting (e.g., AV = RF/RG), with no internal gain fixed.

Operation requires split ±5 V or single 5 V supply, with VCM pin biasing the output common-mode voltage (0 V typical with ±5 V, 2.5 V with 5 V). The ENABLE pin (Pin 7) controls power state, reducing supply current from 20 mA to 1.2 mA in shutdown while placing outputs in high-impedance mode-critical for system-level power sequencing and isolation.

Key Specifications

Pinout & Package

VSSOP-8 package (3.00 mm × 3.00 mm), thermally enhanced for high-speed operation with exposed thermal pad (not electrically connected).

Key Features

Applications

Equivalent & Alternatives

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

Compared with THS4561IRGT and ADA4940-1ACPZ-R7, the LMH6550MM/NOPB uniquely balances 400 MHz bandwidth, −103 dBc HD3, and user-configurable VCM-making it optimal for mixed-signal systems requiring both wideband fidelity and flexible common-mode interface matching.

Availability

LMH6550MM/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 OEM programs.

Supply support for LMH6550MM/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 innovation in high-speed amplifiers and data converter interfaces.

The LMH6550MM/NOPB belongs to TI's high-speed differential amplifier product line, engineered specifically for low-distortion, wideband signal conditioning in ADC driver, video, and communications infrastructure applications.

FAQ

What is the recommended supply configuration for LMH6550MM/NOPB in ADC driver applications?

For optimal distortion performance in ADC driver applications, LMH6550MM/NOPB should be operated with ±5 V supplies. This configuration delivers 400 MHz −3-dB bandwidth, −103 dBc HD3 at 5 MHz, and 0 V output common-mode voltage-matching the input requirements of most high-speed differential-input ADCs. Single 5 V operation is supported but reduces bandwidth to 350 MHz and shifts VCM to 2.5 V.

How does the VCM pin function in LMH6550MM/NOPB, and what happens if left unconnected?

The VCM pin on LMH6550MM/NOPB sets the output common-mode voltage via an internal error amplifier. If left unconnected, internal 50 kΩ resistors bias VCM to mid-supply (0 V with ±5 V, 2.5 V with 5 V). 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.

Can LMH6550MM/NOPB drive 50 Ω differential loads directly, and what external components are required?

Yes, LMH6550MM/NOPB can drive 50 Ω differential loads directly, delivering up to ±75 mA linear output current. Required external components include matched RF/RG gain-setting resistors (e.g., 365 Ω each for unity gain), 0.01 µF + 0.1 µF ceramic bypass capacitors within 3 mm of V+ and V− pins, and a 0.1 µF capacitor from VCM to ground. RO series resistors (e.g., 10–22 Ω) may be added for stability with capacitive loads.

What is the role of the ENABLE pin (Pin 7) in LMH6550MM/NOPB, and how does it affect output behavior?

The ENABLE pin (Pin 7) controls power state: >2.0 V enables normal operation (20 mA supply current); <1.5 V disables the amplifier, reducing supply current to 1.2 mA and placing +OUT/−OUT in high-impedance state. In disabled mode, the signal path remains conductive through external resistors, so input-to-output isolation is poor-intended only for power gating, not signal blocking.

How does LMH6550MM/NOPB achieve single-ended-to-differential conversion without external components?

LMH6550MM/NOPB achieves single-ended-to-differential conversion using its integrated three-channel architecture: the primary differential amplifier paths (IN+/IN− → +OUT/−OUT) operate in inverting mode, while the dedicated VCM feedback loop actively forces output common-mode voltage to the VCM pin reference. When only IN+ is driven and IN− is grounded, the VCM loop maintains output balance and common-mode level-eliminating need for external summing amplifiers or transformers.