MC34670 Datasheet, PDF (1/24 Pages) Freescale Semiconductor, Inc – IEEE 802.3af PD With Current Mode Switching Regulator

Freescale Semiconductor
Advance Information
Document Number: MC34670
Rev. 3.0, 12/2006
IEEE 802.3af PD With Current
Mode Switching Regulator
34670
The 34670 combines a Power Interface Port for IEEE 802.3af
Powered Devices (PD) and a high performance current mode
switching regulator. It allows a designer to build PDs with a minimum
of external components by means of integrating the required IEEE
802.3af functions and all functions necessary to build a high
efficiency DC/DC converter.
On the PD side the 34670 fully supports the IEEE802.3af standard
and provides complete signature and power classification functions.
It controls inrush current limiting and incorporates adjustable
undervoltage lockout. The switching regulator provides excellent line
and load regulation. It drives an external Power MOSFET with sense
resistor.
Features
• Integrated IEEE 802.3af Compliant Interface
• Signature Detection and Classification Functionality
• Integrated Isolation Switch
• Programmable Inrush Current Limiting Control
• Adjustable Undervoltage Lockout
• Input Voltage Range up to 80 V
• Current Mode Control
• Adjustable Oscillator
• Leading Edge Blanking
• Internal Slope Compensation Circuitry
• Input Overvoltage Protection
• 50% Duty Cycle Limitation
• Pb-Free Packaging Designated by Suffix Code EG
POWER OVER ETHERNET
EG SUFFIX (PB-FREE)
98ASB42343B
20-PIN SOICW
ORDERING INFORMATION
Device
Temperature
Range (T_A)
Package
MCZ34670EG/R2 -40°C to 85°C
20 SOICW
PSE HUB OR SWITCH
TX
PHY
RX
HOST
PROCESSOR
48 V POWER
SUPPLY
PSE POWER
CONTROLLER
SWITCH _-48V
GND
RJ-45
CAT 5
CABLE
ETHERNET APPLIANCE (PD)
RX
PHY
TX
HOST
CONTROLLER
-48V
PD POWER
CONTROLLER
ISOLATION SWITCH
34670
DC/DC
Figure 1. 34670 Simplified Application Diagram
* This document contains certain information on a new product.
Specifications and information herein are subject to change without notice.
© Freescale Semiconductor, Inc., 2006. All rights reserved.