MCZ34670EG/R2

Document Number: MC34670 Freescale Semiconductor Rev. 3.0, 12/2006 Advance Information IEEE 802.3af PD With Current 34670 Mode Switching Regulator The 34670 combines a Power Interface Port for IEEE 802.3af Powered Devices (PD) and a high performance current mode POWER OVER ETHERNET 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 EG SUFFIX (PB-FREE) resistor. 98ASB42343B 20-PIN SOICW Features Integrated IEEE 802.3af Compliant Interface ORDERING INFORMATION Signature Detection and Classification Functionality Integrated Isolation Switch Temperature Device Package Programmable Inrush Current Limiting Control Range (T ) A Adjustable Undervoltage Lockout MCZ34670EG/R2 -40C to 85C 20 SOICW 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 RJ-45 PSE HUB OR SWITCH ETHERNET APPLIANCE (PD) TX RX PHY PHY RX TX HOST PSE POWER HOST CONTROLLER CONTROLLER PROCESSOR CAT 5 SWITCH -48V CABLE 48 V POWER GND 34670 SUPPLY PD POWER CONTROLLER ISOLATION SWITCH -48V 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.INTERNAL BLOCK DIAGRAM INTERNAL BLOCK DIAGRAM FREQ HIGH VOLTAGE VPWR VDD REGULATOR 2.5V 8V INTERNAL 5.7V 0.8R SUPPLY R S R POR OSC Q GATE RCLA EN R 3.5V UV or UVLO UNDERVOLTAGE UV or UVLO 5A LOCKOUT + OVERVOLTAGE DETECTION SS 0.3V S CONTROL LOGIC Q 4.5V R 5k PWM COMPARATOR 0.6 - 2.6V CS BLANK 0.4V 1.4V 0.6V + 3 CURRENT ILIM SLOPE GATE LIMITATION COMP COMP DRIVE FB UVLO TEMP 1.2V SENSOR REG R SENSE + DETECT 250mV VIN VOUT RESET Figure 2. 34670 Simplified Internal Block Diagram 34670 Analog Integrated Circuit Device Data 2 Freescale Semiconductor