TI公司的TPS23754/6 是组合了以太网供电(PoE)30W大功率PoE用电装置接口和电流模式DC/DC控制器,非常适合用于隔离的转换器.PoE接口支持IEEE 802.3at (draft)标准,支持高效率的拓扑,具有完整的PoE接口和增强分类特性, 集成了100 V, 0.5欧姆热插拔 MOSFET,可用在IEEE 802.3at (draft)标准兼容设备,视频和VoIP电话,RFID阅读器以及多频带接入点.本文介绍了TPS23754/6的主要特性,方框图, 采用TPS23754的高效转换器电路图,同步的反激电路图,以及TPS23754EVM-383评估板电路图和材料清单(BOM).
The TPS23754/6 is a combined Power over Ethernet (PoE) powered device (PD) interface and current-mode dc/dc controller optimized specifically for isolated converters. The PoE interface supports the IEEE 802.3at (draft) standard.
The TPS23754/6 supports a number of input voltage ORing options including highest voltage, external adapter preference, and PoE preference. These features allow the designer to determine which power source will carry the load under all conditions.
The PoE interface features the new extended hardware classification necessary for compatibility with high-power midspan power sourcing equipment (PSE) per IEEE 802.3at (draft). The detection signature pin can also be used to force power from the PoE source off. Classification can be programmed to any of the defined types with a single resistor.
The dc/dc controller features two complementary gate drivers with programmable dead time. This simplifies design of active-clamp forward converters or optimized gate drive for highly-efficient flyback topologies. The second gate driver may be disabled if desired for single MOSFET topologies. The controller also features internal softstart, bootstrap startup source, current-mode compensation, 78% maximum duty cycle. A programmable and synchronizable oscillator allows design optimization for efficiency and eases use of the controller to upgrade existing power supply designs. Accurate programmable blanking, with a default period, simplifies the usual current-sense filter design trade-offs.
The TPS23754 has a 15 V converter startup while the TPS23756 has a 9 V converter startup. The TPS23754-1 replaces the PPD pin with a no-connect for increased pin spacing.
TPS23754/6主要特性:
Powers up to 30 W (input) PDs
DC/DC Control Optimized for Isolated Converters
Supports High-efficiency Topologies
Complete PoE Interface
Enhanced Classification per IEEE 802.3at(Draft) with Status Flag
Adapter ORing Support
Programmable Frequency with Synchronization
Robust 100 V, 0.5 Ω Hotswap MOSFET
–40℃ to 125℃ Junction Temperature Range
Industry Standard PowerPAD TSSOP-20
主要应用:
IEEE 802.3at (Draft) Compliant Devices
Video and VoIP Telephones
RFID Readers
Multiband Access Points
Security Cameras
图1.TPS23754/6功能方框图
图2.采用TPS23754的高效转换器
图3.TPS23754 的ORing配置
图4.驱动同步的反激电路
TPS23754EVM-383评估板
This User’s Guide describes the TPS23754 EVM (TPS23754EVM-383). TPS23754EVM-383 contains evaluation and reference circuitry for the TPS23754. The TPS23754 is an IEEE 802.3at compliant powered device (PD) controller and power supply controller optimized for isolated converter topologies.
TPS23754EVM-383 is targeted at 25W, active clamp, forward converter applications.
TPS23754EVM-383评估板主要特性:
Efficient, general market design
Self driven, synchronous rectified secondary
25w output power from power over ethernet (POE), 30W output power from a 48V adapter
Operates from either POE or external adaptors (48V)
12V output voltage
评估板应用:
Voice over Internet Protocol–IP telephones
Wireless LAN–Wireless Access Points
Security–Wired IP cameras
图5.TPS23754EVM-383评估板电路图
TPS23754EVM-383评估板材料清单(BOM):
