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IEEE 802.3bt PoE-PD interface with embedded dual active bridge

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Product overview


The PM8805 is a system-in-package for smart power supply of Power over Ethernet (PoE) Powered Devices (PD) and it is applicable for power level up to 99.9 W.

It embeds: two active bridges and their driving circuitry, a charge pump to drive the high-side MOSFETs, the hot swap MOSFET and the interface compliant with IEEE 802.3bt.

The device performs the physical layer classification, providing the indication of successful PSE type identification. A 4-pair PSE is identified and the information is available by a dedicated matrix of Tx signals.

The device works with power either from the Ethernet cable or from an external power source such as a wall adapter, with possible prevalence of the auxiliary source with respect to the PoE.

The PM8805 is suitable to build the interface section of PoE switch mode power supplies targeting the highest conversion efficiency. It provides a PGD signal that can be used to enable a PWM controller, a DC-DC converter or an LED driver.

  • All features

    • Dual active bridge, hot swap MOSFET and PoE-PD interface in a system-in-package
    • 100 V N-ch MOSFETs with 0.2 Ω total path resistance for each active bridge
    • 100 V, 0.1 Ω high-side N-ch hot swap MOSFET
    • PoE-PD single-signature interface compliant with IEEE 802.3bt / at / af
    • Supports 4-pair PoE applications
    • Supports 12 V auxiliary sources
    • Identifies which kind of PSE (standard or legacy) is connected with and provides successful IEEE802.3bt / at / af classification indication as a combination of the T0, T1 and T2 signals (open drain)
    • Smart operational modes
    • Programmable classification current with 3.3 ms delay
    • Optional Autoclass feature
    • Advanced energy-saving MPS timings
    • Two-step hot swap current protection: DC with 1 ms delay and short-circuit with 10 μs delay
    • Controlled pre-charge of the output capacitor
    • PGD signal (open drain) to enable an external PWM controller
    • Thermal shutdown protection

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STMicroelectronics - PM8805

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Quality and Reliability

Part Number Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
QFN 8x8x1 43L P 0.5 6 Dice pad Industrial Ecopack2



QFN 8x8x1 43L P 0.5 6 Dice pad

Material Declaration**:


Marketing Status



QFN 8x8x1 43L P 0.5 6 Dice pad



RoHS Compliance Grade


(**) The Material Declaration forms available on may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.

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