Self-adaption dynamic detection circuit for switch power source

Abstract

The invention discloses a self-adaption dynamic detection circuit for a switch power source. The self-adaption dynamic detection circuit is used for generating a self-adaption dynamic voltage VREF which dynamically changes along with loads. The self-adaption dynamic detection circuit for the switch power source comprises a switching period to current conversion circuit, a low pass filtering circuit and a VREF generation circuit. The switching period to current conversion circuit controls timing of an OSC in a switch power source control chip, and therefore different control signals can be generated, the control signals are used for switching on different current branches in the switching period to current conversion circuit, corresponding voltages that change slowly are obtained when branch voltages that are generated are filtered by the low pass filtering circuit, and the self-adaption dynamic voltage VREF is output when the voltages pass through the VREF generation circuit. The self-adaption dynamic detection circuit is advantaged by good dynamic characteristics and small output voltage overshoot; a technical problem that large dynamic detection deviation is caused due to the fact that conventionally the VREF voltage (reference voltage) cannot change along dynamically along with load conditions and therefore voltage difference values detected at different loads are inconsistent can be solved.

Description

technical field [0001] The invention relates to a circuit in the technical field of switching power supplies, in particular to a switching power supply adaptive dynamic detection circuit. Background technique [0002] Switching power supplies are common components in electronic systems. In recent years, in current low-power applications, such as 5W and 10W mobile phone chargers, primary-side feedback switching power supplies have become more and more widely used. The schematic diagram of the primary side feedback charger is as follows: figure 1 shown. [0003] This structure can realize the output constant current CC and constant voltage CV process control. The realization principle of constant current is: [0004] I 0 = 1 2 * T d e m T * N ...

AI Technical Summary

Problems solved by technology

[0010] Aiming at the deficiencies in the prior art, the present invention provides a switching power supply adaptive dynamic detection circuit with the advantages of good dynamic characteristics and small output voltage overshoot, which solves the problem that the traditional VREF voltage (reference voltage) cannot dynamically follow the load condition The voltage difference detected by different loads is inconsistent, resulting in a technical problem of large dynamic detection deviation

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