Monolithic Power Systems Inc. MP8005DF-LF

Overview

MP8005DF-LF from Monolithic Power Systems is an IEEE 802.3af-compliant Powered Device (PD) interface and PWM controller for PoE-powered systems. It integrates detection, classification, inrush current limiting, thermal protection, and a synchronous buck controller with 100V/1Ω integrated main switch, 460mA temperature-compensated current limit, and user-programmable output voltage via external resistor divider. Used in VoIP telephones and security camera systems requiring isolated 13W PoE power delivery.

For engineers reviewing the MP8005DF-LF datasheet, MP8005DF-LF pinout, MP8005DF-LF application, or MP8005DF-LF equivalent, this page provides verified technical context, real-world design meanings of key specs, validated pin functions, confirmed alternative parts with functional differences, and supply support for industrial PoE deployments.

Technical Context

The MP8005DF-LF implements full IEEE 802.3af PD functionality: 25kΩ detection resistance, 10.2–13V classification turn-on threshold, and 21–23V turn-off threshold with hysteresis. Its dual-gate driver architecture supports isolated synchronous rectification with programmable delay (40–200ns via RDELAY) to prevent cross-conduction.

It features integrated thermal shutdown at 150°C, foldback current limiting during overload, and UVLO at 38–42V (rising) with 1.4V diode-drop compensation. The error amplifier delivers 0.26–0.46 mA/V transconductance and 0.28–0.36 V/V translator gain, enabling stable regulation across 220–300 kHz switching frequency.

Key Specifications

Pinout & Package

TSSOP-20-EP package with exposed thermal pad; 0.65 mm pitch, 6.5 mm × 4.4 mm body, JEDEC MO-153 compliant. Exposed pad must be soldered to PCB ground plane for thermal performance (θJC = 50°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PoE PD interface applications.

Compared with LT4275AIMSE#PBF and NCP1094DR2G, the MP8005DF-LF uniquely combines integrated 100V switch, programmable gate delay, and thermal foldback in a TSSOP-20 package-enabling compact, robust 13W PoE designs without external high-voltage FETs or complex timing networks.

Availability

MP8005DF-LF is available at Aetrix Electronics and suitable for VoIP telephony, security camera systems, industrial network cards, and remote internet power applications requiring stable component supply, RoHS-compliant packaging, and long-term lifecycle support.

Supply support for MP8005DF-LF 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.

The MP8005 belongs to MPS's PoE PD controller product line, engineered specifically for IEEE 802.3af-compliant powered devices requiring integrated detection, classification, inrush control, and synchronous DC-DC regulation in space-constrained applications.

FAQ

What is the maximum input voltage the MP8005DF-LF can withstand?

The MP8005DF-LF supports absolute maximum VDD of +100V, but its recommended operating range is 0–57V per IEEE 802.3af specifications. Sustained operation above 57V risks exceeding thermal limits and triggering shutdown, though the 100V rating protects against transient surges such as PSE open-circuit testing or lightning-induced spikes on Ethernet lines.

Does the MP8005DF-LF support IEEE 802.3at (PoE+)?

No, the MP8005DF-LF is designed exclusively for IEEE 802.3af (Type 1) with 13W maximum power. It lacks the higher classification current thresholds (e.g., 35–60mA for Class 4) and extended voltage tolerance required for 802.3at. For PoE+, consider MPS's MP8017 or Analog Devices' LT4275 series.

How is output voltage programmed on the MP8005DF-LF?

Output voltage is set using an external resistor divider from VOUT to AGND, connected to the VFB pin. With a 0.818V internal reference, a standard 10kΩ/20kΩ divider yields 2.45V; scaling the upper resistor achieves 3.3V (e.g., 30.1kΩ/10kΩ) or 5V (e.g., 61.9kΩ/10kΩ). Layout must minimize noise pickup on VFB trace.

What is the purpose of the RDELAY pin?

RDELAY sets the delay between SYNCGATE falling and MAINGATE rising to prevent cross-conduction in synchronous rectifier topologies. A resistor from RDELAY to AGND (e.g., 100kΩ) produces ~100ns delay, critical for isolating gate drive timing in flyback or forward converters where transformer leakage inductance causes propagation delays.

Can the MP8005DF-LF operate without the external CSS capacitor?

No - the CSS capacitor is mandatory for controlled inrush current limiting. Omitting it causes unregulated current surge into the input capacitor, leading to immediate thermal shutdown or damage to the internal 1Ω switch. Typical values range from 1nF to 10nF, selected to limit peak RTN current to ≤460mA during startup.

Is the exposed thermal pad electrically connected internally?

Yes - the exposed pad is internally connected to VSS (Pin 9), the Ethernet negative return. It must be soldered to a dedicated PCB copper pour tied to VSS and thermally coupled to internal ground planes. Failure to connect it degrades θJA from 105°C/W to >150°C/W, risking thermal shutdown under 400mA load.

What happens if the CLASS resistor is omitted?

Omitting the CLASS resistor defaults the device to Class 0 (up to 15.4W), but the MP8005DF-LF will still draw classification current (38–41.2mA) when VDD reaches 10.2–13V. Without RCLASS, the PSE may misclassify or limit power; for guaranteed 12.95W (Class 3), use 4.42kΩ per datasheet Table 1.