Monolithic Power Systems Inc. MP5018GD-Z

Overview

MP5018GD-Z from Monolithic Power Systems is a 5V, 1A–5A adjustable current-limit power switch with reverse current blocking, 5.8V fast over-voltage clamp, integrated 45mΩ N-channel MOSFET pair, and bi-directional EN/FAULT pin for fault signaling. It operates in hot-swap and PCIe power rail protection applications where inrush control, transient suppression, and bidirectional fault isolation are required.

For engineers reviewing the MP5018GD-Z datasheet, MP5018GD-Z pinout, MP5018GD-Z application, or MP5018GD-Z equivalent, this device delivers precise current limiting (adjustable via ILIMIT resistor), sub-10μs OVP response, thermal latch-off protection, and soft-start timing control - all in a QFN-12 (2mm×3mm) package suitable for space-constrained 5V system rails.

Technical Context

The MP5018GD-Z integrates dual back-to-back N-channel MOSFETs to block reverse current up to –1.2A with 7μs deglitch filtering and automatic recovery when VCC > VOUT – 2mV. Its charge-pump-based gate drive enables full enhancement of the internal FETs across 4.5V–5.5V input range while maintaining 45mΩ R_DS(on) at 25°C.

It implements three independent protection loops: UVLO (4.0V threshold with 300mV hysteresis), OVP (5.8V clamp with 10μs typical response), and current limiting (programmable 0.5A–5A or fixed 3A). Fault states - thermal shutdown (>175°C), reverse current, or UVLO - are signaled via tri-state EN/FAULT pin voltage levels (low/mid/high).

Key Specifications

Pinout & Package

MP5018GD-Z is housed in a thermally enhanced QFN-12 package (2mm × 3mm, 0.5mm pitch) with exposed thermal pad (Pin 12 + Pad) for PCB heat sinking. Pin 6 is NC; all other pins have defined functions per Monolithic Power Systems Rev. 1.02 datasheet.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar current-limit switch applications.

Compared with TCK127BG and TPS25940A, MP5018GD-Z uniquely combines SAS-driven DEVSLP compatibility, integrated 5.8V OVP, and true reverse-current blocking in a 2mm×3mm footprint - making it optimal for space-constrained, firmware-coordinated storage and peripheral expansion systems.

Availability

MP5018GD-Z is available at Aetrix Electronics and suitable for HDD/SSD power rail protection, PCIe hot-swap card insertion, and gaming console storage expansion requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for MP5018GD-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-performance analog and power ICs, with design centers in the US, China, and Taiwan, and global manufacturing partnerships.

The MP5018 belongs to MPS's eFuse and current-limit switch product line, engineered specifically for hot-swap, PCIe, and storage interface power integrity - emphasizing fast fault response, minimal board area, and firmware-coordinated power management.

FAQ

What is the maximum continuous current MP5018GD-Z can deliver without thermal shutdown?

At 25°C ambient with proper PCB copper pour (≥200mm² thermal pad area), MP5018GD-Z sustains 3A continuously due to its 45mΩ R_DS(on) and 1.8W power dissipation rating. At 85°C ambient, derating reduces usable current to ~2.1A before thermal shutdown triggers at 175°C junction temperature.

Can MP5018GD-Z be used with a 3.3V input supply?

No - MP5018GD-Z requires minimum 4.5V input for guaranteed operation per its UVLO threshold (4.0V nominal). Below 4.5V, the device disables output and pulls EN/FAULT low; it is not rated or characterized for 3.3V operation.

How does the EN/FAULT pin indicate reverse current fault versus thermal fault?

Both faults drive EN/FAULT to mid-level (~1.3V), but reverse current fault recovers automatically when VCC exceeds VOUT by >2mV, while thermal fault remains latched until EN or SAS is toggled or input power is cycled - enabling firmware to distinguish root cause via timing behavior.

Is the SS pin compatible with ceramic capacitors only, or can electrolytic types be used?

Ceramic capacitors are strongly recommended for the SS pin due to their low ESR and stable capacitance over temperature/voltage. Electrolytic capacitors introduce leakage and tolerance drift that distort soft-start timing accuracy and may cause inconsistent ramp rates across temperature.

What is the purpose of the NC pin (Pin 6), and can it be left unconnected?

Pin 6 is designated No Connection per MPS datasheet Rev. 1.02 and must remain unconnected - no internal circuitry links to it. Leaving it floating is safe; routing or soldering to any net risks unintended coupling or mechanical stress on the QFN package.

Does MP5018GD-Z support simultaneous shutdown across multiple devices?

Yes - the EN/FAULT pin supports wired-OR configuration: connecting multiple EN/FAULT pins together allows one device's fault condition (e.g., thermal event) to pull all shared pins to mid-level, triggering coordinated shutdown in multi-rail systems like PCIe risers or modular servers.

What is the minimum recommended ILIMIT resistor value, and why?

The minimum recommended ILIMIT resistor is 215Ω (for 5A limit), per Table 2 in the datasheet. Lower values risk exceeding internal current-sense amplifier compliance range and may cause inaccurate limiting or instability - 215Ω is the validated lower bound for reliable 5A operation.