STEVAL-POE005V1 Data brief 12V/8A, active clamp forward converter, Power Over Ethernet (PoE) IEEE 802.3bt compliant reference design Features Features of the PM8805 PoE-PD interface: System in package integrating a double active bridge, a hot-swap MOSFET and a PoE-PD Supports legacy high power, 4-pair applications 100 V N-ch MOSFETs with 0.2 total path resistance for each active bridge Identifies which kind of PSE (standard or legacy) is connected to, and provides successful IEEE802.3 af /at /bt classification indication as combination of the T0, T1 and T2 signals (open drain) Smart operational mode selection through the STBY, FAUX and RAUX control signals QFN 56 8x8mm package with 43 pins and 6 exposed pads Features of the PM8804 PWM controller: PWM peak current mode controller Input operating voltage up to 75 V Internal high voltage start up regulator with 20 mA capability Programmable fixed frequency up to 1 Mhz Soft start up with adjustable time Soft turn off (optionally disabled) Dual 1 A , low side complementary gate drivers PK GATE2 optionally turned off for reduced consumption Product summary 80% maximum duty cycle with internal slope compensation High power PoE PD, 12 V QFN 16 3x3mm package with exposed pad STEVAL- up to 8 A active clamp POE005V1 forward evaluation board Description PWM peak current mode controller for PoE and PM8804 This reference design represents a 12 V, 8 A converter solution ideal for various telecom systems applications including building safety and security or surveillance, with a PoE-PD IEEE802.3bt PoE-PD interface and a DC-DC active clamp forward converter. interface with integrated PM8805 The PoE-PD interface is based on the PM8805 system in package device with two dual-active bridge active bridges and an IEEE 802.3bt compliant Powered Device (PD) interface. It can be used in all medium-to-high power 2P and 4P high efficiency PoE and PoE+ applications. The DC-DC active clamp forward converter is designed around the PM8804 PWM controller, which is an integrated solution for smart and efficient 48 V converters, featuring a programmable oscillator for the switching frequency, adjustable slope compensation, dual complementary low-side drivers with programmable dead time, programmable soft start, soft turn off and a programmable current sense blanking time. DB3699 - Rev 3 - June 2019 www.st.com For further information contact your local STMicroelectronics sales office.STEVAL-POE005V1 Efficiency 1 Efficiency The STEVAL-POE005V1 reference design consists of a PoE interface compliant with the IEEE 802.3bt standard and a forward active clamp DC-DC converter that receives DC voltage from the PoE interface. The figure below shows the efficiency of a single forward converter and the overall efficiency including the PoE interface power losses. Figure 1. STEVAL-POE005V1 overall and DC-DC forward efficiency The dotted lines indicate the STEVAL-POE005V1 efficiency at different DC input voltages applied to RJ45 connector J1. The continuous line indicates the DC-DC forward efficiency, which does not include the following losses associated with the PoE interface section: RJ45 connector J1 PoE data transformer T1 common chokes T7 and T8 placed on the two power supply pairs PM8805 interface that integrates the dual power MOS bridges and a hot swap MOSFET Forward converter input filter This efficiency is measured between output test points TP8/TP9 and input test points TP5/TP6 of the forward converter. DB3699 - Rev 3 page 2/7