Features
 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

Applications
 High power wireless data systems
 Security cameras
 Access points
 Public information displays
 PoE lighting systems
Description
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.