Analog Devices Inc./Maxim Integrated MAX3822UCM

Overview

MAX3822UCM from Maxim Integrated is a +3.3V, 2.5Gbps quad limiting amplifier designed for fiber-optic receiver front-ends. It features differential CML outputs, programmable channel-select (CS) for single/dual/quad operation, four independent loss-of-power (LOP) indicators, and supports input sensitivity down to 20mV_p-p. It is used in multichannel optical interconnects where low deterministic jitter (<30ps p-p) and precise threshold detection are critical.

For engineers reviewing the MAX3822UCM datasheet, MAX3822UCM pinout, MAX3822UCM application, or MAX3822UCM equivalent, key selection criteria include its 4-channel LOP monitoring capability, on-chip 50Ω CML back-termination, 120ps output edge speed, 700mW quad-channel power dissipation, and compatibility with transimpedance amplifiers like MAX3825 in high-speed optical modules.

Technical Context

The MAX3822UCM integrates four independent limiting amplifier chains, each with a linear-gain stage followed by high-gain limiting stages and an offset-corrected CML output buffer. Each channel includes a DC-cancellation loop (cutoff ~150kHz) using external CZ_± capacitors to suppress low-frequency PWD and pattern-dependent jitter.

Power detection uses rectified output from the first gain stage compared against a common threshold set by VTH and R_TH, delivering 4dB typical voltage hysteresis (2dB optical). Channel enable/disable is controlled via TTL-compatible CS pin logic: open = channel 1 only, VCC = channels 1–2, GND = all four channels active.

Key Specifications

Pinout & Package

MAX3822UCM is housed in a 48-pin TQFP-EP (7mm × 7mm × 1.0mm) package with an exposed ground pad for thermal and electrical performance. The EP must be soldered to PCB ground.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX3822UCM, MAX3825UCM serves a complementary upstream role rather than substitution, while LMH0384SQ/NOPB integrates additional CDR functionality at higher data rates - neither offers pin-compatible replacement, but both address adjacent positions in optical receiver signal chains.

Availability

MAX3822UCM is available at Aetrix Electronics and suitable for optical interconnect modules, multichannel receiver assemblies, and digital cross-connect systems requiring stable component supply, long-term lifecycle support, and guaranteed commercial-temperature performance.

Supply support for MAX3822UCM 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and RF solutions for communications, computing, and industrial markets.

The MAX3822UCM belongs to Maxim's high-speed optical receiver IC product line, engineered specifically for post-TIA signal conditioning in multi-gigabit fiber-optic links with stringent jitter and power-monitoring requirements.

FAQ

What is the operating supply voltage range for the MAX3822UCM?

The MAX3822UCM operates from a single +3.3V supply, with absolute maximum ratings allowing VCC from +3.0V to +3.6V. Operation outside this range risks damage or functional failure. The device is characterized and guaranteed across the full 0°C to +85°C temperature range at these voltages, and its internal biasing and CML output levels are optimized specifically for +3.3V operation - using other supply voltages is not supported.

How does the channel-select (CS) pin configure operation modes in the MAX3822UCM?

The CS pin on the MAX3822UCM determines active channel count: left open enables channel 1 only; tied to VCC enables channels 1 and 2; tied to GND enables all four channels. This configuration shuts down unused amplifier chains to reduce power consumption - for example, dual-channel mode draws ~137mA versus 265mA in quad mode. The CS logic is TTL-compatible and requires no external pull-up/down resistors beyond the defined connections.

What external components are required for basic operation of the MAX3822UCM?

The MAX3822UCM requires three types of external components: (1) a single resistor (R_TH) from VTH to GND to set the LOP threshold level; (2) four 0.033µF capacitors (one per CZ_± pair) to configure the offset-correction loop bandwidth (~150kHz); and (3) AC-coupling capacitors only if upstream differential logic is not CML - the inputs are internally terminated to VCC and do not require external termination when driven by CML sources like MAX3825.

Does the MAX3822UCM support AC-coupled inputs, and what are the implications?

Yes, the MAX3822UCM supports AC-coupled inputs, but it is not required when driven by CML-output TIAs such as the MAX3825 - its inputs are internally terminated to VCC with 50Ω and DC-biased for direct connection. AC coupling becomes necessary only when interfacing with non-CML differential sources (e.g., LVDS or PECL), to block incompatible common-mode voltages. Improper AC coupling (e.g., incorrect capacitor value or placement) can degrade high-frequency response and increase deterministic jitter.

What is the purpose and implementation of the CZ_± pins on the MAX3822UCM?

The CZ_± pins on the MAX3822UCM provide access to the offset-correction loop for each channel. A capacitor (recommended 0.033µF) connected between each CZ₊/CZ₋ pair sets the low-frequency cutoff (~150kHz) of the DC cancellation loop, which removes baseline drift and suppresses pattern-dependent jitter. This loop actively adjusts input buffer bias to maintain zero CML output offset - critical for minimizing pulse-width distortion in high-speed NRZ data streams processed by the MAX3822UCM.