The EVAL-LTC9105-AZ is an IEEE 802.3bt-compliant Type 3, Class
6 Power over Ethernet (PoE) powered device (PD) with port telemetry
via I2C. The evaluation board features the LTC9105 PD
interface controller, MAX5974C switching regulator controller, the
LT4321 PoE ideal diode bridge controller, and the ADuM1252 I2C
isolator.
The LTC9105 provides IEEE 802.3af-, IEEE 802.3at-, and IEEE
802.3bt-compliant interfacing with port voltage and current telemetry
via I2C. It utilizes an external, low channel resistance, RDS(ON)
(34mΩ typical), N-channel, hot-swap metal-oxide semiconductor,
field-effect transistor (MOSFET), and 50mΩ sense resistor. Automatic
maintain power signature (MPS) keeps the port connected
when the current drops to a low level.
The MAX5974C controls a DC/DC converter utilizing a highly efficient
active-clamp forward converter topology with synchronous
rectification and provides an isolated 5V/9.2A output. The LT4321
controls eight low RDS(ON) (57mΩ typical), N-channel MOSFETs
to further improve end-to-end power delivery efficiency and ease
thermal design. The ADuM1252 isolates I2C data between the
LTC9105 and a host controller on a nonisolated ground domain.
The EVAL-LTC9105-AZ is configured as a Class 6 PD and accepts
up to 51W of delivered power from a power sourcing equipment
(PSE) via its RJ45 connector (J1). The EVAL-LTC9105-AZ can be
powered by a local 55V DC power supply using the auxiliary supply
input terminals. With the DC590B I2C interface board connected
to the EVAL-LTC9105-AZ, the EVAL-LTC9105-AZ graphical user
interface (GUI) displays port telemetry and configuration options.
