Load connection identification circuit of switching power supply and multi-port charger

Abstract

The invention discloses a load connection identification circuit of a switching power supply. The load connection identification circuit comprises a ripple detection circuit, a judgment circuit and acontrol circuit. Ripple signals of the output port of the switching power supply are detected in a coupling mode through the arrangement of the ripple detection circuit. Whether an output port is connected with a load or not can influence a ripple signal, the detection circuit detects ripple signals of the output port, so that the judgment circuit can judge whether the output port is connected with a load or not according to the detected ripple signals and outputs a judgment result to the control circuit, and the control circuit can recognize the load connection state of the output port and correspondingly control output of the switching power supply. According to the invention, the use of a current sampling resistor is avoided, the increase of heating points and system power loss can be avoided, and the system efficiency is improved. Moreover, the identification blind area of the output current is reduced, and the identification accuracy of load connection is improved. In addition, the invention further discloses a load connection identification circuit of the multi-port charger, and the load connection identification circuit also has the above beneficial effects.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a load connection identification circuit of a switching power supply and a multi-port charger. Background technique [0002] Charger, also known as charging treasure and mobile power supply, is a charging device that provides a stable power supply for electronic equipment containing batteries. It often consists of a stable power supply (providing stable working voltage and sufficient current) plus necessary constant current, limit Voltage and protection functions and other control circuits. [0003] With the rapid popularization of smart devices and smart phones, multi-port intelligent power distribution chargers (ie, multi-port chargers) are increasingly favored by users. Each power supply port of the switching power supply of the multi-port charger is compatible with the fast charging protocol, and only slightly increases the system cost, so the multi-port charger ha...

AI Technical Summary

Problems solved by technology

Therefore, the protocol chip can not only judge whether the power supply port (that is, the output port) of the charger is connected to the load through the signal lines D+, D-, CC1 and CC2, but only by measuring the voltage signals on the VBUS and GND lines in the USB line. or current signal to judge

[0004] In the prior art, most of the switching power supplies on the market adopt the conventional identification circuit of "judging whether the output of the switching power supply is connected to the load by measuring the voltage signal at both ends of the current detection resistor". The schematic diagram is as follows figure 1 shown, however using a current sense resistor set at the output of the switching power supply (such as figure 1 R3) in the system will increase the power loss when the system is working normally, which will reduce the system efficiency and increase a hot spot; and the resolution point Iout=Vref / R3 of the output current (Iout) flowing through the current sampling resistor, considering the component cost and Component errors, such as large offset voltage (Voffset), reference voltage (Vref) errors, current sampling resistor errors, and noise interference in the comparator, the resolution point of the output current is about 400mA, that is, when Iout<400mA, the protocol The chip cannot judge whether the charger output is connected to the load

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