PoE power supply is a common power supply method used by network devices, which transmits network and power simultaneously through network cables. In order to reduce the loss on the line, the PoE power supply usually uses a higher supply voltage in exchange for a lower current, thereby reducing the voltage drop caused by the line resistance of the network cable. However, the higher power supply voltage cannot be directly used by network equipment, and needs to be matched with a step-down circuit to achieve power supply to the existing equipment.
To solve this problem, PeerSafe has launched a single-chip PoE interface controller, the AS7064BQ, which supports IEEE 8023AF AT protocol with characteristic impedance detection, power grading and time stamping, and inrush impulse current control. The chip also integrates a bypass switch and a built-in power switch to act as a switching power supply to step down the voltage of the connected devices.
The charging head network has obtained a reference design based on the AS7064BQ launched by PeerSafe Technology, which supports PoE power input, output power of 12W, and output specification of 12V1A, which can meet the power supply needs of webcams and other devices. The chip adopts QFN5*5-28 package, which has excellent heat dissipation performance. Here's a detailed breakdown of this reference design to see how it was designed.
PeerSafe AS7064BQ reference design soldered network interface, two rectifier bridges, input and output filter capacitors and transformers.
The measured weight of the PCBA module is about 245g。
PeerSafe AS7064BQ reference design at a glance, the lower left corner is welded with the network interface, and two rectifier bridges are welded in the upper left corner. One electrolytic capacitor is welded at the top for input filtering, the right side is welded with a transformer, and two electrolytic capacitors are welded at the bottom right corner for output filtering.
A TVS diode, PeerSafe AS7064BQ chip, rectifier Schottky diode and resistor capacitors are soldered on the back.
At the heart of this reference design is the PeerSafe AS7064BQ, which has an integrated bypass switch and switch, supports Power over Ethernet interface control, and has a built-in switching power supply for step-down output. The built-in switching power supply adopts primary side feedback, supports constant current and constant voltage control, the output power of constant current mode is set by the current sampling resistor, and the chip also supports a variety of working modes to ensure the conversion efficiency of constant voltage mode.
The chip has an integrated 100V withstand voltage of 067 conductive resistance bypass switch tube, integrated 150V withstand voltage 035 Conductive resistance switches. The chip has a built-in power-on soft start and built-in adaptive peak current control. The chip has inrush current limit and current limit, supports power supply type indication, built-in VCC over-voltage protection, under-voltage protection and clamping protection, and has over-temperature protection function. The chip adopts QFN5*5-28L package, which is suitable for IP cameras, IP**, wireless APs and IoT device applications.
PeerSafe AS7064BQ Fact Sheet.
Rectifier bridge model MB10S for input polarity conversion.
The other rectifier bridge is of the same model.
TVS diodes are used for overvoltage protection.
The filter capacitor comes from Aihua.
The specification is 100v47 F.
The transformer core is wound with tape insulation.
The SS56 Schottky diode is used for output rectification.
The two output filter capacitors are from Aihua and are both 16V220 F.
PoE transmits power through network cables, eliminating the need to deploy AC power and adapters at the device, simplifying equipment installation, and obtaining a wide range of applications for webcams and APs with the advantage of not requiring power supply. The single-chip PoE interface controller AS7064BQ launched by PeerSafe integrates a bypass switch and a switch tube, and the chip has a built-in switching power supply with primary side feedback, which can realize the power receiving protocol and isolated step-down output on a single chip.
The AS7064BQ supports PoE power supply and power adapter switching, has complete internal protection functions and power-on soft start functions, and adopts a compact QFN package, which has a high degree of integration and saves board area, meeting the use of high-performance and small-volume PoE power supply equipment. Ideal for webcams, APs, and IoT devices, providing a simple and efficient PoE power supply solution.