Chip simplifies Ethernet powered device design

Edited by the Electronicstalk editorial team Feb 18, 2005

The LTC4267 is an IEEE802.3af power over Ethernet controller that features an integrated switching regulator to greatly simplify powered device design.

Linear Technology has introduced the LTC4267, an IEEE802.3af power over Ethernet (PoE) controller that features an integrated switching regulator to greatly simplify powered device (PD) design.

Offered in a space saving 3 x 5mm DFN package, this IC ensures compliance with the IEEE 802.3af PoE standard and includes an onboard 25kOhm signature resistor and classification current source.

The internal 100V power MOSFET provides protection against inductive voltage spikes from long cables, while the guaranteed low leakage prevents corruption of the 25kohm signature resistance.

The LTC4267's dual-level inrush current limit allows for seamless interface with legacy PoE systems.

The LTC4267 fits in PDs, like digital voice-over-IP phones, network wireless access points, security cameras, or any small Ethernet-connected device that requires less than 13W.

The LTC4267 includes an onboard constant-frequency current mode DC/DC controller, easily tailored to a wide variety of power supply voltage and load current requirements.

Constant frequency operation is maintained down to very light loads, minimising low frequency noise generation.

Slope compensation can be programmed with external resistors to allow for fast transient response with minimum output capacitance.

By integrating the switching regulator, the LTC4267 significantly simplifies PD design.

With only the switching regulator's pass FET, a transformer and a few small components required externally, the LTC4267 provides the smallest Power over Ethernet solution available.

Specified over the commercial and industrial temperature grades, pricing for the LTC4267 begins at $2.10 each for 1000-piece quantities.