PM8801
High-efficiency, IEEE 802.3at compliant, integrated PoE-PD
interface and PWM controller
Datasheet
-
production data
Description
The PM8801 integrates a standard compliant
Power over Ethernet (PoE) interface and a
current mode PWM controller to simplify the
design of the power supply sections of all
powered devices.
The PoE/PoE+ interface incorporates all the
functions required by the IEEE 802.3at including
detection, classification, undervoltage lockout
(UVLO) and inrush current limitation.
The PM8801 specifically performs IEEE802.3at
Layer1 hardware classification, providing an
indication of type 2 PSE successful detection to
the rest of the system.
The PM8801 has been designed to work with
power either from the Ethernet cable connection
or from an external power source such as a wall
adapter, ensuring prevalence of the auxiliary
source with respect to the PoE interface.
The DC/DC section of the PM8801 features a
programmable oscillator frequency, an adjustable
slope compensation, dual complementary low-
side drivers with programmable delay time and
internal temperature sensor.
The PM8801 targets high-efficiency conversion at
all load conditions supporting flyback, forward,
forward active clamp and synchronous
rectification.
Table 1. Device summary
Part number
PM8801
HTSSOP24
PM8801TR
Tape and reel
Package
Packing
Tube
HTSSOP24
Features
•
IEEE 802.3at compliant PD interface
•
Works with power supplied from Ethernet LAN
cables or from local auxiliary sources
•
Successful IEEE802.3at Layer1 classification
indicator
•
Integrated 100 V, 0.45
Ω,
1 A hot-swap
MOSFET
•
Accurate 140 mA typ. inrush current level
•
Programmable classification current
•
Sleep mode with LED indicator and Maintain
Power Signature (MPS)
•
Precise DC current limit set at 640 mA typ.
•
Integrated high-voltage startup bias regulator
•
Thermal shutdown protection
•
Current mode pulse width modulator
•
Programmable oscillator frequency
•
80% maximum duty cycle with internal slope
compensation
•
Support for flyback, forward, forward active
clamp, flyback with synchronous rectification
Applications
•
VoIP phones, WLAN AP
•
WiMAX CPEs
•
Security cameras
•
PoE/PoE+ Powered device appliances
July 2013
This is information on a product in full production.
DocID018560 Rev 2
1/37
www.st.com
37
Contents
PM8801
Contents
1
Typical application circuit and block diagram . . . . . . . . . . . . . . . . . . . . 6
1.1
1.2
Application circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Block diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2
3
Pin descriptions and connection diagram . . . . . . . . . . . . . . . . . . . . . . 10
Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1
3.2
3.3
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4
PD interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Indication of successful 2-event classification . . . . . . . . . . . . . . . . . . . . . 20
Undervoltage lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Inrush and DC current limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Sleep mode / MPS mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
LED driving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Wakeup from sleep mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
High-voltage startup regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5 V bias regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5
PWM controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5.1
5.2
5.3
5.4
5.5
5.6
Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Delay time control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Soft-start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
PWM comparator / slope compensation . . . . . . . . . . . . . . . . . . . . . . . . . 30
Current limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Thermal protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2/37
DocID018560 Rev 2
PM8801
Contents
6
7
8
Auxiliary sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
HTSSOP24 mechanical data & package dimensions . . . . . . . . . . . . . . 34
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
DocID018560 Rev 2
3/37
List of tables
PM8801
List of tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Pin descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Electrical characteristics - interface section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Electrical characteristics - SMPS section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Value of the external classification resistor for the different PD classes of power . . . . . . . 20
LED duty cycle selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
TSSOP24 mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4/37
DocID018560 Rev 2
PM8801
List of figures
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Simplified application schematic for powered devices using PM8801
in forward active clamp configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Simplified application schematic for powered devices using PM8801
in synchronous flyback configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
PM8801 internal block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Block diagram of the DC/DC section of the PM8801 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Pin connections (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
PM8801: reference schematic of the PoE classification logic. . . . . . . . . . . . . . . . . . . . . . . 20
T2P signal when connected to PSE supporting 1-event classification . . . . . . . . . . . . . . . . 21
T2P signal when connected to PSE supporting 2-event classification . . . . . . . . . . . . . . . . 21
Line transient response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Sleep mode with pulsed MPS current. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
LED enabled at startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Wakeup sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
PWM frequency vs. R
T
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Delay time vs. RDT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Timing relationship between output drivers as a function of DT . . . . . . . . . . . . . . . . . . . . . 29
Overload (left) and short-circuit (right) behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Smooth transition from POE to auxiliary source and vice-versa. . . . . . . . . . . . . . . . . . . . . 32
HTSSOP24 package dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
DocID018560 Rev 2
5/37
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
