Monolithic Power Systems Inc. MP8001DS-LF-P

Overview

MP8001DS-LF-P from Monolithic Power Systems is an IEEE 802.3af-compliant Powered Device (PD) controller for Power over Ethernet systems, integrating a 100V, 1.2Ω DMOS pass device, 420mA current limit, open-drain Power Good output, and thermal shutdown at 135°C. It performs detection (26.1kΩ signature), classification (4.42kΩ resistor), and inrush-limited startup for VoIP phones and security cameras.

For engineers reviewing the MP8001DS-LF-P datasheet, MP8001DS-LF-P pinout, MP8001DS-LF-P application, or MP8001DS-LF-P equivalent, key selection criteria include its 420mA current limit (vs. 810mA for MP8001A), SOIC-8 package with verified pin functions, UVLO thresholds (38–42V rising / 30.2–32.8V falling), and guaranteed 10.2–13V classification turn-on voltage.

Technical Context

The MP8001DS-LF-P implements IEEE 802.3af PD detection via 26.1kΩ resistance sensing and classification using externally set resistor values (e.g., 4.42kΩ for Class 3). Its internal 100V DMOS switch enables direct connection to PoE midspan or endspan PSEs without external high-voltage MOSFETs.

Operation includes controlled inrush limiting (120–200mA typical), thermal foldback protection triggered at 135°C with 40°C hysteresis, and latch-off Power Good signaling with 75–225μs deglitching. The device remains inactive below 30.2V and enables regulation only above 38V, ensuring safe power-up sequencing.

Key Specifications

Pinout & Package

MP8001DS-LF-P uses an industry-standard SOIC-8 package (5.0mm × 6.2mm, 1.27mm pitch) with exposed pad not connected internally. Pin 7 is NC (no connect); all other pins have defined electrical roles per IEEE 802.3af PD interface requirements.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Powered Device controller applications.

Compared with MP8001ADS-LF-P, the MP8001DS-LF-P provides lower current capability optimized for cost-sensitive Class 3 applications, while LT4275AIMSE#PBF adds programmability and PoE+ compatibility at the expense of increased bill-of-materials and firmware integration effort.

Availability

MP8001DS-LF-P is available at Aetrix Electronics and suitable for VoIP telephony, security camera systems, and network interface cards requiring stable component supply, RoHS-compliant packaging, and long-term industrial lifecycle support.

Supply support for MP8001DS-LF-P 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, headquartered in California and serving global industrial, automotive, and communications markets since 1997.

The MP8001 product line delivers fully integrated, IEEE 802.3af-compliant Powered Device controllers targeting cost-effective, space-constrained PoE endpoints where simplicity, reliability, and qualification-ready performance are critical.

FAQ

What is the function of Pin 1 (ILIM) on MP8001DS-LF-P?

Pin 1 sets the current limit threshold via an external resistor to ground. With 178kΩ, it configures the device for 420mA limiting. An open circuit disables current foldback entirely, while incorrect values cause inaccurate trip points or disable thermal protection-always verify resistor tolerance and placement per MPS AN-107.

Can MP8001DS-LF-P operate with 802.3at (PoE+) PSEs?

Yes, but only in legacy 802.3af mode. The MP8001DS-LF-P lacks the two-event classification required for 802.3at and will negotiate as a Class 3 (12.95W) device even when connected to a PoE+ PSE, drawing no more than 420mA regardless of PSE capability.

How does the Power Good (PG) output behave during thermal shutdown?

PG goes high-impedance (open-drain off) during thermal shutdown, removing the active-low assertion. It remains deasserted until VDD drops below the classification lower threshold (~10.2V), then re-enables only after full restart sequence-including detection, classification, and inrush charging-is completed.

What is the minimum input capacitance required for stable startup?

The datasheet specifies a minimum 5μF input capacitor on the RTN–VDD rail. Smaller values risk insufficient energy storage during inrush, causing repeated thermal cycling; larger values extend charge time linearly but require verification against thermal limits using the 120–200mA inrush current spec.

Is Pin 7 (NC) safe to tie to ground or leave floating?

Pin 7 is unconnected internally and must remain unconnected on the PCB. Tying it to ground or any voltage introduces parasitic paths that may disrupt internal biasing or compromise ESD robustness-MPS explicitly states this pin has no bond wire and zero electrical function.

Does MP8001DS-LF-P support automatic retry after overcurrent fault?

No. After overcurrent or thermal shutdown, the device latches off and requires full removal and reapplication of VDD (i.e., PSE cycle) to reset. There is no internal auto-retry timer; system-level supervision must manage recovery if continuous operation is required.

What is the role of the 26.1kΩ detection resistor between DET and RTN?

This resistor forms the IEEE-mandated detection signature: the PSE applies ≤10.1V and measures current draw to identify the 26.1kΩ ±3% value. Deviation outside tolerance causes detection failure-use 1% metal-film resistor with tight thermal coefficient to maintain accuracy across -40°C to +85°C.