Simulated demagnetization sampling method and system for switching power supply output sampling

Abstract

The present invention discloses a method and a system for simulation of demagnetization sampling of switching power supply output sampling. The present invention provides a method for simulation of demagnetization sampling of switching power supply output sampling. The method comprises the steps of: discharging a switching power supply primary sampling peak voltage to perform simulation of demagnetization; determining a relation of the primary sampling peak voltage and demagnetization time; and at least partially based on the sampling peak voltage of the current period, the conduction time of a power switch and discharge speed information of the last period, determining positions of sampling points.

Description

technical field [0001] This disclosure relates to integrated circuits. More specifically, some embodiments of the present invention relate to a method and system for analog demagnetization sampling of switching power supply output sampling. Background technique [0002] Taking the traditional primary-side control flyback switching power supply (PSR AC / DC Flyback Converter) as an example, the principle of constant voltage (CV) control and output sampling of the chip is introduced. Figure 1A A simplified block diagram of a conventional switching power supply is shown. As shown in Figure 1, Vline is the line voltage obtained by rectifying the AC input source, Cbulk is the filter capacitor, Rst is the high-voltage start-up resistor, and the turns ratio of the primary side, secondary side, and auxiliary winding of the three-winding transformer is Np:Ns: Na, Rcs is the primary current detection resistor, D2 is the secondary rectifier diode, Cout is the output capacitor, S1 is th...

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Problems solved by technology

[0010] It can be seen that this FB sampling point generation circuit has significant shortcomings. It needs to use the demagnetization time Tdem of the previous cycle to generate the sampling point of the current cycle, that is, the position of the sampling point is proportional to the previous Tdem time, and is proportional to the current cycle. The relationship between Tdem time is uncertain, which may cause some sampling problems

For example, when the system Vcs jumps from a large value to a small value, the Tdem time will also change from a large value to a small value, such as Figure 4 As shown, while the second Tdem is shorter, but the position of the sampling point is proportional to the previous longer Tdem, which will cause subsequent sampling errors

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