National Semi Introduces High Power PoE PD Controller with Auxiliary Power Support
National Semiconductor Corp. introduced a Power-over-Ethernet (PoE) powered device (PD) controller with adjustable output current level and the ability to interface with any dc-dc converter topology.
National’s new LM5073, which the company claims is the industry’s highest power PoE controller, integrates a programmable interface port including a hot-swap controller that exceeds the standard IEEE 802.af specifications, allowing designers to operate PoE appliances at power levels of 30W or more. For greater flexibility, the LM5073 separates the PD interface from the dc-dc converter to support a wide variety of isolated and non-isolated dc-dc converter topologies. Applications include IP telephony, remote security cameras, card readers, wireless access points, PoE-enabled industrial automation systems and point-of-sale terminals.
The LM5073 PoE controller supports PD designs that are fully compliant with the IEEE 802.3af standard. If more power is required, the low RDS(ON) hot-swap MOSFET and programmable dc current limit extend the range of LM5073 applications to more than twice the power level of IEEE 802.3af compliant devices. The LM5073 also provides the flexibility for the PD to accept power from unregulated auxiliary sources such as ac adapters and solar cells in a variety of configurations. The 100V maximum voltage rating simplifies selection of the voltage suppressor that protects the PD from network transients.
The LM5073 joins National’s family of PoE devices, including the LM5072, which integrates a dc-dc controller with the higher PoE power capability of the LM5073, the LM5070, which integrates a 375 mA PoE interface circuit with a dc-dc controller, and the LM5071, a single chip solution specifically designed for PoE devices that operate from alternative power sources.
National’s LM5073 can be used with the DP83848 single port or DP83849 dual port 10/100 Mbps Ethernet physical layer device to provide a space and cost effective system solution for PoE Ethernet compliant designs. The power for the node (following the PoE standard) is supplied by standard CAT5 cable and connectors via the National devices, which eliminates the need for expensive external power supplies while delivering full Ethernet connectivity.
Offered in a 14-pin TSSOP with exposed pad for improved thermal performance, the LM5073 integrates a 100V, 700mΩ, N-channel MOSFET as well as the PD signature and under-voltage lockout resistors. It provides configurable front and rear auxiliary inputs that accept power from ac adapters to reduce the power draw on the PoE power sourcing equipment. Complementary control outputs provide a flexible interface to the best dc-dc converter topology for the particular application. For non-isolated applications, the LM5073 can be paired with National’s LM5007 and LM5010 buck regulators or popular LM5574, LM5575 and LM5576 high-voltage SIMPLE SWITCHER® product family. For higher-power isolated systems, the LM5073 can be paired with National’s LM5020 or LM5026 pulse-width modification (PWM) controllers.
National’s new LM5073 is available now and priced at $1.30 in 1,000-unit quantities.
