• Fully Compatible with 802.3af/at Specifications
• 100V 0.45Ω PD Integrated Pass Switch
• 30W maximum power
• 100mA PD Inrush Current limit
• 900mA PD Normal Operation Current Limit
• Auxiliary Adaptor ORing Support
• Flexible Topology:

                       Primary-Side Regulated (PSR) Flyback (250kHz/400kHz Selectable)

                       Secondary-Side Regulated (SSR) Flyback (Programmable Frequency)

• Output Diode Compensation in PSR Mode
• Cycle-by-Cycle Current Sense Limit
• Precision Voltage Reference
• Frequency Modulation for EMI reduction
• Programmable Soft-start
• OLP Compensation for Wide-Input Range
• Externally Programmable Thermal Shutdown
• Programmable Line Under Voltage Lockout (UVLO) with Adjustable Hysteresis
• Hiccup Protection for OLP, SCP, OVP and Thermal Shutdown 

The SQ33607 is a fully integrated IEEE 802.3 af/at PoE compliant Powered Device (PD) power supply controller. It includes the PD interface and a high efficiency PSR/SSR Flyback controller.

The PD interface has all the functions to comply with IEEE 802.3af/at, including detection, 1-event and 2-event classification, ~100mA inrush current limit, 900mA operation current limit, auto maintain power signature (AMPS), as well as 100V rated Hot-swap MOSFET. The PD interface also supports Auxiliary Adaptor Oring and type-2 indicator.

The PWM controller is specifically optimized for low cost, small size isolated flyaback configuration, with either primary-side regulation (PSR) or secondary-side regulation (SSR). The device integrates a high voltage start-up circuit, using current mode, quasi constant-frequency control to avoid sub-harmonic oscillations and no need of slope compensation.

The SQ33607 is available in a QFN 4mm x 4mm -20 pin package.