Features and Benefits
- IEEE 802.3af/at-Compliant PD Interface Circuit
- -36V to -57V Startup Input Voltage Range
- 92% (typ) Efficiency
- Demonstrates Isolated 12W Flyback DC-DC Converter
- Isolated +12V Output at 1A
- 300kHz Switching Frequency
- Configurable for Optocoupler Feedback Operation
- Scalable to 12V Class 4 PD
- PD Detection and Configurable Classification Signatures
- 2-Event Classification or Wall Adapter Detect Output
- Inrush Current Limit of 135mA (typ)
- Internal UVLO at -35.6V (typ)
- Evaluates Endspan and Midspan Ethernet Systems
- Simplified Wall Adapter Interface
- Proven PCB Layout
- Fully Assembled and Tested
The MAX5969A evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board featuring the MAX5969A IEEE 802.3af/at-compliant network powered device (PD) interface controller and the MAX5974A inductive-feedback, spread-spectrum, current-mode PWM controller. The EV kit is designed as a high-performance, compact, and cost-efficient solution for a Class 3 (scalable to Class 4) PD used in Power-over-Ethernet (PoE) applications.
The EV kit demonstrates the full functionality of the MAX5969A, such as PD detection signature, PD classification signature, inrush current control, and input undervoltage lockout (UVLO). The EV kit also features an isolated 12W, 300kHz switching-frequency, synchronous-rectified flyback DC-DC converter topology, using the MAX5974A inductive-feedback, current-mode PWM controller. The EV kit circuit is configured for an output voltage of +12V and provides up to 1A load current using primary-side regulation. The surface-mount transformer provides up to +1500V galvanic isolation for the output.
The EV kit receives power from IEEE® 802.3af/at-compliant power-sourcing equipment (PSE). The PSE provides the required -36V to -57V DC power over an unshielded twisted-pair Ethernet network cable to the EV kit's RJ45 magnetic jack. The EV kit features a 1 x 1Gb Ethernet RJ45 magnetic jack and two full-bridge diodes for separating the DC power provided by an endspan or midspan Ethernet system.
The EV kit circuit can also be powered by a +36V to +57V wall adapter power source, applied at the WAD_IN and WAD_GND PCB pads. When a wall adapter power source is detected, it always takes precedence over the PSE source, allowing the wall adapter to power the EV kit.
Warning: The EV kit is designed to operate with high voltages. Dangerous voltages are present on this EV kit and on equipment connected to it. Users who power up this EV kit or the power sources connected to it must be careful to follow safety procedures appropriately to work with high-voltage electrical equipment.
Under severe fault or failure conditions, this EV kit may dissipate large amounts of power, which could result in the mechanical ejection of a component or of component debris at high velocity. Operate this kit with care to avoid possible personal injury.
- IEEE 802.3af/at Powered Devices
- IP Phones, Wireless Access Nodes, IP Security Cameras
- WiMAX™ Base Station