Analog Devices Inc./Maxim Integrated MAX9628ATC+

Overview

MAX9628ATC+ from Maxim Integrated is a 4V/V fixed-gain, fully differential amplifier optimized for driving high-speed pipeline ADCs up to 16-bit resolution. It delivers 3.6nV/√Hz input-referred voltage noise, -91dBc/-97dBc HD2/HD3 at 10MHz (5V supply), and 1.15GHz large-signal bandwidth with 25µA shutdown current. Its VOCM-controlled output common-mode voltage enables transformerless DC-coupled interfacing to ADCs like the MAX19588 in medical imaging front-ends.

For engineers reviewing the MAX9628ATC+ datasheet, MAX9628ATC+ pinout, MAX9628ATC+ application, or MAX9628ATC+ equivalent, this page provides verified specifications, validated pin functions, real-world use cases in ATE and instrumentation, and two confirmed alternative amplifiers with documented gain and distortion trade-offs.

Technical Context

The MAX9628ATC+ employs voltage-feedback architecture with on-chip precision gain resistors (RG = 125Ω, RF = 500Ω) to achieve factory-set 4V/V differential gain and minimize parasitic capacitance at virtual ground nodes. Its dual-loop design separates differential signal amplification from common-mode control via the VOCM pin, ensuring output balance (–77dB error at 10MHz) without degrading AC performance.

It supports both single-ended-to-differential (with external 50Ω termination) and differential-to-differential operation, with input common-mode range extending to –0.4V (at VCC = 3.3V) and output swing of ±(VCC – 1.0V) into 500Ω. Shutdown mode reduces supply current to ≤50µA while maintaining fast 0.6µs turn-on time.

Key Specifications

Pinout & Package

MAX9628ATC+ uses a 12-pin, 3mm × 3mm TQFN-EP package with exposed pad (EP) connected to VEE. The pinout is optimized for high-frequency layout: symmetric IN+/IN– and OUT+/OUT– placement minimizes skew, while dual VCC (pins 5,6) and dual VEE (pins 10,11) reduce supply impedance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX9626ATC+ and LMH5401IRGT, the MAX9628ATC+ uniquely balances 4V/V gain, integrated 64Ω termination, and –91dBc HD2 at 10MHz in a 3mm × 3mm package-making it optimal for space-constrained, high-linearity ADC driver designs where external component count must be minimized.

Availability

MAX9628ATC+ is available at Aetrix Electronics and suitable for medical imaging systems, automated test equipment, high-performance instrumentation, and communications infrastructure requiring stable component supply across extended temperature ranges.

Supply support for MAX9628ATC+ 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

Maxim Integrated (now part of Analog Devices) designs precision analog and mixed-signal ICs for demanding industrial, automotive, and communications applications.

The MAX9626/MAX9627/MAX9628 family was engineered specifically as high-fidelity, low-noise differential ADC drivers for 12–16-bit pipeline converters operating from DC to 1.35GHz, emphasizing integration, thermal robustness, and production-tested performance over –40°C to +125°C.

FAQ

What is the guaranteed gain accuracy of the MAX9628ATC+ over temperature?

The MAX9628ATC+ guarantees ±0.2% gain error over the full –40°C to +125°C operating range, as confirmed in the Electrical Characteristics table under "Gain Error" with conditions VOUT+, VOUT– = –1V to +1V. This tight tolerance is achieved through laser-trimmed on-chip resistors and is independent of supply voltage variation between 2.85V and 5.25V. The MAX9628ATC+ maintains this specification without external calibration.

Can the MAX9628ATC+ operate with a single 3.3V supply and ground-referenced input?

Yes, the MAX9628ATC+ supports single-supply operation with VEE = GND and VCC = +3.3V. Its input common-mode voltage range extends down to –0.4V (relative to VEE) at this supply, allowing ground-referenced single-ended inputs without negative rail. This capability is explicitly specified in the Electrical Characteristics table under "Common-Mode Input Voltage Range" for MAX9628. The MAX9628ATC+ achieves this using internal level-shifting circuitry that preserves DC coupling to the ADC.

How does the VOCM pin affect output balance and distortion performance?

The VOCM pin sets the DC common-mode level of both OUT+ and OUT– outputs without disturbing differential signal integrity. As shown in Figures 41–43, CMRR remains ≥54dB up to 10MHz, ensuring VOCM variations do not inject common-mode error into the differential output. However, driving VOCM with high source impedance (>1kΩ) degrades CMRR above 10MHz and increases HD2/HD3 by up to 6dB. The MAX9628ATC+ requires a low-impedance VOCM source (e.g., op-amp buffer) for optimal distortion performance.

What is the maximum load capacitance the MAX9628ATC+ can drive without oscillation?

The MAX9628ATC+ is characterized to drive up to 10pF capacitive load without sustained oscillation, as stated in the Electrical Characteristics table under "Capacitive Load". This limit applies to direct connection to ADC input capacitors or PCB trace capacitance. For loads exceeding 10pF (e.g., long traces or multiple ADC inputs), a series 5Ω–10Ω isolation resistor should be placed near the MAX9628ATC+ output pins to maintain stability. This requirement is consistent across all three variants (MAX9626/27/28) and verified in production testing.

Does the MAX9628ATC+ require external termination resistors when used with a 50Ω single-ended source?

Yes - when interfacing a 50Ω single-ended source, the MAX9628ATC+ requires an external 50Ω resistor from the unused input (e.g., IN–) to ground to maintain symmetry and minimize gain error. Although the device integrates 64Ω termination resistors (RT+ and RT–), their value is optimized for 50Ω source matching only when both inputs are actively driven differentially. The MAX9628ATC+ datasheet explicitly recommends this external resistor in the "Typical Operating Circuit" and "Applications Information" sections to ensure <0.1% gain error.