Monolithic Power Systems Inc. MP5981GLU-Z

Overview

MP5981GLU-Z from Monolithic Power Systems is a monolithic hot-swap Intelli-Fuse IC integrating a 1.1mΩ R_DS(ON) high-side MOSFET, current mirror, on-die temperature sensor, and fault reporting logic. It delivers up to 50A continuous current at room temperature (60A with airflow), operates from 4V–16V input, and functions in standalone or controller-coordinated hot-swap systems for live backplane insertion. Used in server power distribution units to limit inrush and prevent backplane voltage droop during PC card insertion.

For engineers reviewing the MP5981GLU-Z datasheet, MP5981GLU-Z pinout, MP5981GLU-Z application, or MP5981GLU-Z equivalent, key selection criteria include its integrated current/temperature sensing, programmable over-current threshold via CLREF, latch/hiccup mode selection, GOK fault signaling, and parallel operation capability for >50A load management.

Technical Context

The MP5981 implements a closed-loop gate control architecture that regulates the integrated MOSFET's V_GS to enforce current limiting during start-up and steady-state operation. Its current-limit reference (CLREF) is dynamically clamped-low (≈635mV) when V_OUT < 80% of V_IN, rising to 1.6V once V_OUT ≥ 80% of V_IN-enabling controlled soft-start and full-power transition.

It features dual protection paths: a 14µs response for normal over-current events using CS/CLREF comparison, and a 200ns fast-turn-off circuit triggered at 100A short-circuit current. Fault reporting occurs via open-drain GOK (latched or hiccup-mode) and D_OC outputs, while IMON and VTEMP provide real-time analog monitoring signals for system-level supervision.

Key Specifications

Pinout & Package

LGA-32 (5mm × 5mm) package with exposed thermal pad; optimized for high-current PCB routing and thermal dissipation in dense server power modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar hot-swap eFuse applications.

Compared with TPS2491RGER and LTC4215IMS#PBF, MP5981GLU-Z delivers higher current density (50A), eliminates external sensing components, and integrates temperature-aware protection - reducing bill-of-materials cost and improving reliability in space-constrained server and telecom power modules.

Availability

MP5981GLU-Z is available at Aetrix Electronics and suitable for server blade power distribution, disk drive hot-swap modules, PC card power management, and networking line card protection requiring stable component supply and long-term lifecycle support.

Supply support for MP5981GLU-Z 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

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-efficiency power management ICs for computing, cloud infrastructure, and industrial applications.

The MP5981 belongs to MPS's Intelli-Fuse product line, designed specifically for intelligent, self-contained hot-swap protection in high-density, high-reliability power systems where minimal external components and robust fault handling are critical.

FAQ

What is the maximum continuous current rating for MP5981GLU-Z under natural convection?

The MP5981GLU-Z delivers 50A continuous current at ambient temperature (T_A = 25°C) with no forced airflow. This rating assumes proper PCB copper area (≥4 oz, 2-layer thermal pad), and operation within the recommended junction temperature range (–40°C to +125°C). Derating applies above 60°C ambient.

How does the MP5981GLU-Z implement short-circuit protection without external components?

It uses an internal fast-turn-off circuit triggered when sensed current reaches 100A, independent of the CLREF-based current limit loop. This path responds in 200ns by directly disabling the gate driver, bypassing the slower analog control loop - ensuring protection even during sub-microsecond fault transients.

Can MP5981GLU-Z operate without an external hot-swap controller?

Yes. The MP5981GLU-Z supports standalone operation: connect ON/PD to VDD3 for automatic turn-on, set CLREF and RCS for desired current limit, and use SS capacitor for soft-start timing. No external controller is required for basic hot-swap functionality.

What is the function of the VTEMP pin, and how is it calibrated?

VTEMP provides a linear 8.7mV/°C analog output referenced to GND, covering 0°C to 140°C. At 25°C, it outputs ~370mV. Calibration is factory-trimmed; no user adjustment is needed. It connects directly to an ADC input for real-time die temperature monitoring and thermal throttling decisions.

How does parallel operation ensure balanced current sharing between multiple MP5981GLU-Z devices?

During soft-start, all paralleled MP5981s actively regulate their gate voltages to maintain identical V_CS levels across matched RCS resistors. This forces equal current division from turn-on through steady state, verified to ±5% imbalance at 50A per device - no external current-balancing circuitry required.

What fault conditions cause the GOK pin to assert, and is it recoverable?

GOK asserts low on over-current (exceeding CLREF-defined limit for >180µs), short-circuit (100A detection), over-temperature (143°C junction), or FET drain-source short. Recovery depends on MODE pin: latch mode requires power cycle; hiccup mode automatically retries after ~560ms if fault clears.

Is the 3.0V LDO (VDD3) output capable of powering external circuitry?

Yes. VDD3 supplies up to 14mA at 3.05V (±145mV) and can power external logic, level shifters, or small sensors. A 1µF ceramic capacitor must be placed adjacent to VDD3 and GND. For lower dropout, an external 3.3V supply may be applied to VDD3 to bypass the internal regulator.