PM8805 PoE-PD interface Datasheet

PM8805 Datasheet, PDF, Equivalent


Part Number

PM8805

Description

IEEE 802.3bt PoE-PD interface

Manufacture

STMicroelectronics

Total Page 30 Pages
Datasheet
Download PM8805 Datasheet


PM8805
PM8805
IEEE 802.3bt PoE-PD interface with embedded dual active bridge
VFQFPN43 8x8mm exposed pad
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
Datasheet - Production data
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.
Table 1. Device summary
Part number
Package
Packing
PM8805TR
VFQFPN
8X8X1.0 43L
PITCH 0.5
Tape and reel
April 2019
This is information on a product in full production.
DS12813 Rev 2
1/48
www.st.com

PM8805
Contents
Contents
PM8805
1 Typical application circuit and block diagram . . . . . . . . . . . . . . . . . . . . 6
1.1 Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 Pin description and connection diagram . . . . . . . . . . . . . . . . . . . . . . . . 8
3 Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.2 Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.3 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4 PM8805 overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.1 Detection and DET pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 Boot and reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3 PoE classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.4 Autoclass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.5 Charge pump and VCP pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.6 Input Bridges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.7 Hot swap, CTRL and PGD pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.8 Hot swap protections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.9 Interface with a DC/DC converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.10 Auxiliary sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.11 Operation modes and STBY, FAUX, RAUX command signals . . . . . . . . 32
4.12 Type T0, T1, T2 output signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.13 Standby and MPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.14 Special operation modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5 Thermal aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.1 Power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.2 Overtemperature protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2/48 DS12813 Rev 2


Features PM8805 IEEE 802.3bt PoE-PD interface wi th embedded dual active bridge VFQFPN4 3 8x8mm exposed pad Features  Dual a ctive bridge, hot swap MOSFETand PoE-PD interface in a system-in-package  1 00 V N-ch MOSFETs with 0.2 Ω total pat h resistance for each active bridge. 100 V, 0.1 Ω high-side N-ch hot swap MOSFET  PoE-PD single-signature int erface compliant with IEEE 802.3bt / at / af  Supports 4-pair PoE applicati ons  Supports 12 V auxiliary sources  Identifies which kind of PSE (stan dard or legacy) is connected with and p rovides successful IEEE802.3bt / at / a f classification indication as a combin ation of the T0, T1 and T2 signals (ope n drain)  Smart operational modes Programmable classification current w ith 3.3 ms delay.  Optional Autoclas s feature  Advanced energy-saving MP S timings  Two-step hot swap current protection: DC with 1 ms delay and sho rt-circuit with 10 us delay.  Contro lled pre-charge of the output capacitor  PGD signal (open drain) to enable an external PWM.
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