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.
- Dual active bridge, hot swap MOSFETand 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 us 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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