PoEPower supply is a commonly used power supply mode for network equipment, which transmits network and power simultaneously through network cables.In order to reduce the loss on the line,PoEThe power supply usually uses a higher supply voltage in exchange for a lower current, thus reducing the voltage drop caused by the line resistance of the network.The higher power supply voltage cannot be directly used by network equipment, and it needs to be matched with a step-down circuit to supply power to existing equipment.
To solve this problem, Zoomshare Technology has launched a single chipPoEInterface controller AS7064BQ, which supports IEEE 802.3af/at protocol, has the functions of characteristic impedance detection, power grading and time marking, and surge surge current control.A bypass switch tube is also integrated inside the chip, and a power switch tube is built in, which is used as a switching power supply to step-down power supply the connected equipment.
The charging head network has obtained the reference design launched based on the crowdsourcing technology AS7064BQ. This reference design supportsPoEThe power input, output power is 12W, and output specification is 12V1A, which can meet the power supply requirements of webcams and other equipment.The chip is packaged with QFN5 * 5-28, which has excellent heat dissipation performance.Here is a detailed analysis of this reference design to see how it is designed.
Analysis of the reference design of Zhongxiang Technology AS7064BQ
Zhongxiang Technology AS7064BQ refers to the design of welding network interface, two rectifier bridges, input and output filter capacitors and transformers.
The measured weight of PCBA module is about 24.5g.
At the bottom left corner, the network interface is welded, and two rectifier bridges are welded at the top left.An electrolytic capacitor is welded at the top for input filtering, a transformer is welded at the right side, and two electrolytic capacitors are welded at the bottom right corner for output filtering.
A TVS diode is soldered on the back, the Zhongxiang Technology AS7064BQ chip, the rectifier Schottky diode, resistance and capacitor and other components.
The core of this reference design is Zhongxiang Technology AS7064BQ. This chip integrates bypass switch tube and switch tube, supports Ethernet power supply interface control, and built-in switching power supply is used for step-down output.The built-in switching power supply adopts primary side feedback, and supports constant current and constant voltage control. The output power of constant current mode is set by the current sampling resistance. The chip also supports multiple working modes to ensure the conversion efficiency of constant voltage mode.
The chip is internally integrated with a 100V withstand 0.67 Ω conduction bypass switch tube and a 150V withstand 0.35 Ω conduction switch tube.The chip has built-in power on soft start and built-in adaptive peak current control.The chip has surge current limit and current limit, supports power supply type indication, built-in VCC overvoltage protection, undervoltage protection and clamping protection, and has overheating protection function.The chip is packaged with QFN5 * 5-28L and is suitable for IP camera, IP phone, wireless AP and Internet of Things equipment applications.
All share technology AS7064BQ information.
The model of rectifier bridge for input polarity conversion is MB10S.
The other rectifier bridge has the same model.
TVS diode is used for overvoltage protection.
The filter capacitor is from Aihua.
The specification is 100V47 μ F.
Transformer core is insulated by winding tape.
SS56 Schottky diode is used for output rectification.
The two output filter capacitors are from Aihua, with specifications of 16V220 μ F.
Summary of charging head network
PoETransmission of power through network cable eliminates the need to deploy AC power supply and adapter at the equipment, simplifies the installation of equipment, and has the advantage of no power supply. It has been widely used by webcams and APs.The single chip PoE interface controller AS7064BQ launched by Zoomshare Technology is internally integrated with a bypass switch tube and a switch tube. The chip is built with a switching power supply fed back from the primary side. A single chip can realize the power receiving protocol and isolated step-down output.
The AS7064BQ supports PoE power supply and power adapter switching. It has complete protection functions and power on soft start functions inside, and uses a compact QFN package, which has high integration and saves board area to meet the needs of high-performance and small volume PoE power supply equipment.It is very suitable for webcams, APs and IoT devices, and provides a simple and efficient PoE power supply solution.