Analog Devices Inc./Maxim Integrated MAX9381EUA+

Overview

MAX9381EUA+ from Maxim Integrated is a differential data and clock D flip-flop operating at up to 3.0GHz with PECL/ECL compatibility, 328ps typical propagation delay, 0.2ps_RMS added random jitter, and dual-supply operation (V_CC = 2.25V–5.5V / V_EE = –2.25V––5.5V). It serves as a high-speed edge-triggered register in precision clock distribution systems for DSLAMs and base stations.

For engineers reviewing the MAX9381EUA+ datasheet, MAX9381EUA+ pinout, MAX9381EUA+ application, or MAX9381EUA+ equivalent, key selection criteria include guaranteed 3.0GHz clock frequency, low-power ECL/PECL operation, input clamping for open-input stability, ±2kV HBM ESD rating, and µMAX package thermal performance (155°C/W with airflow).

Technical Context

The MAX9381EUA+ implements a master-slave D flip-flop architecture with differential inputs (D/D̅, CLK/CLK̅) and outputs (Q/Q̅), supporting both positive- and negative-edge triggering via clock input swapping. Its bipolar process enables high-speed switching while maintaining tight timing control across –40°C to +85°C.

Input clamping uses internal 75kΩ pull-down resistors to V_EE, ensuring stable outputs when inputs are open or held at V_EE. Output termination requires 50Ω to V_CC – 2V (PECL mode) or equivalent Thevenin network to preserve signal integrity at 3.0GHz.

Key Specifications

Pinout & Package

The MAX9381EUA+ is housed in an 8-pin µMAX package (3.05mm × 3.05mm × 0.8mm), optimized for high-frequency layout with low thermal resistance (155°C/W at 500LFPM airflow) and integrated bypass capacitor placement support.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed differential D flip-flop applications.

Compared with MC100EP52DG and ADCLK944BCPZ-R7, the MAX9381EUA+ uniquely balances 3.0GHz performance, ultra-low power, dual-supply flexibility, and intrinsic open-input robustness-making it optimal for space-constrained, thermally sensitive telecom and test equipment where reliability under partial connectivity is critical.

Availability

MAX9381EUA+ is available at Aetrix Electronics and suitable for DSLAM line cards, wireless base station clock trees, central office synchronization systems, automated test equipment, and precision timing modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX9381EUA+ 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 high-performance analog and mixed-signal ICs for precision timing, power management, and data conversion applications.

The MAX9381EUA+ belongs to Maxim's high-speed timing portfolio, engineered specifically for low-jitter, low-power differential clock and data registration in telecom infrastructure and automated test systems.

FAQ

What supply configurations does the MAX9381EUA+ support?

The MAX9381EUA+ supports two distinct supply modes: PECL operation with V_CC = 2.25V–5.5V and V_EE = 0V, or ECL operation with V_CC = 0V and V_EE = –2.25V––5.5V. This dual-mode capability allows the same MAX9381EUA+ footprint to serve both positive- and negative-rail systems without redesign. Bypassing each supply with 0.1µF and 0.01µF ceramic capacitors is mandatory for stable 3.0GHz operation.

How does the MAX9381EUA+ handle unconnected inputs?

The MAX9381EUA+ incorporates internal 75kΩ pull-down resistors on all four differential inputs (D, D̅, CLK, CLK̅) tied to V_EE, ensuring defined logic states and stable Q/Q̅ outputs even when inputs are left floating or driven to V_EE. This prevents metastability in backplane or modular systems where connectors may be partially populated. The MAX9381EUA+ truth table explicitly guarantees differential-low output behavior under these conditions.

What is the recommended termination for MAX9381EUA+ outputs?

The MAX9381EUA+ outputs (Q and Q̅) must be terminated with matched 50Ω resistors to V_CC – 2V in PECL mode (or equivalent Thevenin network), as specified in the datasheet. Mismatched termination causes signal distortion, increased jitter, and degraded common-mode rejection. For single-ended extraction, both Q and Q̅ require identical termination; using only one output degrades timing accuracy and increases crosstalk sensitivity in the MAX9381EUA+.

Can the MAX9381EUA+ be used as a T flip-flop?

Yes-the MAX9381EUA+ can be configured as a T flip-flop by connecting Q to D and Q̅ to D̅, producing a divided-by-two output relative to the input clock. This configuration maintains the MAX9381EUA+'s full 3.0GHz maximum clock frequency, provided board trace delays and setup/hold margins are preserved. The internal input clamps ensure reliable startup even if initial states are undefined.

What thermal considerations apply to the MAX9381EUA+ in µMAX package?

The MAX9381EUA+ in 8-pin µMAX has a junction-to-ambient thermal resistance of 155°C/W with 500LFPM airflow and 221°C/W in still air. At 35mA supply current and 3.3V supply, power dissipation reaches ~115mW; thus, ambient temperature must stay below +75°C in sealed enclosures without forced cooling. The MAX9381EUA+ datasheet specifies derating above +70°C (4.5mW/°C), making thermal vias and copper pour essential for sustained 3.0GHz operation.