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The Design Of High-precision PFM Type AC-DC Switching Power Supply Chip With Primary Side Feedback

Posted on:2014-02-05Degree:MasterType:Thesis
Country:ChinaCandidate:K J LiFull Text:PDF
GTID:2268330425960052Subject:Electronic Science and Technology
Abstract/Summary:PDF Full Text Request
Now Switching power supply is constantly developing toward a higher efficiency,smaller size and lighter direction.In order to achieve output voltageregulation,traditional secondary side feedback converter need to sample the outputvoltage and comparing with precision reference voltage source and then through theoptocoupler feedback to the circuit of the primary side of the chip.But theprimary-side converter is directly sampling the signal of the auxiliary winding, toachieve the purposes of the precise control of the output with electricalisolation.Primary side feedback converter system relative to the secondary sidefeedback system of the converter can save a reference voltage source and isolationoptocoupler as well as around the assisted circuit, making the system more compactand smaller. Using the PFM control mode,so you can get a very low standby powerconsumption.On the research of the PFM type AC-DC switching power supply withprimary side feedback has an extremely important significance.Basis on the study of primary feedback switching power supply,put forward anew type of primary feedback loop control system.The chip module is determined bythe control loop system analysis and design and then set the primary feedbackconverter performance indicators and the important module indicator parameters,thendesign and simulate modules circuit in detail.The chip unique uses a open-loopstructure and an additional compensation of the error amplifier to control the currentof clock,thus controlling the switching frequency.So in the chip from EA to PFMcontrol output has a very high gain, to achieve high-precision constant-voltage controland the cable drop compensation of output voltage.Accurate constant current controlloop to achieve high-precision constant current control and primary windinginductance compensation. Using fast peak current control mode,to achievecompensation for the input voltage changing and the output over current or shortcircuit protection function.In addition, the chip also has a soft-start and overvoltageprotection function.Based on1um40V high-voltage BiCMOS process,the circuit of the chip wasdesigning and simulating and through tapeout verification.Finally,testing the DC parameters and system of the chip, test results show that the parameters and functionsof the chip to meet the design target.
Keywords/Search Tags:high precision, primary side feedback, pulse frequency modulation, switching power supply, constant voltage and constant current control
PDF Full Text Request
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