Circuit and method for switch power supply feedback voltage detection and sampling and holding

A technology of sampling and holding circuit and feedback voltage, which is applied to electrical components, regulating electrical variables, and output power conversion devices, etc. The effect of low requirements, high precision, and reduction of power supply material costs and post-test costs

Inactive Publication Date: 2012-03-21
深圳市矽湾微电子有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the accuracy of these existing technologies is not high, the error of the sampled feedback voltage is large, and the output voltage of the system cannot be precisely controlled
And the consistency of the transformer parameters is high, which increases the product cost

Method used

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  • Circuit and method for switch power supply feedback voltage detection and sampling and holding
  • Circuit and method for switch power supply feedback voltage detection and sampling and holding
  • Circuit and method for switch power supply feedback voltage detection and sampling and holding

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Embodiment Construction

[0028] The present invention is further described by examples below, but it should be noted that the purpose of announcing the embodiments is to help further understand the present invention, but those skilled in the art can understand: without departing from the spirit of the present invention and the appended claims Various substitutions and modifications are possible within the scope. Therefore, the present invention should not be limited to the content disclosed in the embodiments, and the protection scope of the present invention is subject to the scope defined in the claims.

[0029] figure 1 is a typical schematic diagram of a switching power supply with transformer auxiliary winding feedback. As shown in the figure, the transformer 10 in the figure has three windings, namely the primary coil, the secondary coil and the auxiliary coil. Correspondingly, Np is the number of turns of the primary coil, Ns is the number of turns of the secondary coil, and Na is the number o...

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PUM

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Abstract

The invention provides a circuit and a method for switch power supply feedback voltage detection and sampling and holding. The circuit provided by the invention comprises a clock control circuit, a control sampling clock, a sampling and holding circuit, a waiting state control circuit, a learning state control circuit, an increment control circuit, a system control circuit and a delay circuit, wherein the sampling and holding circuit samples an input voltage at different time in two paths and selects a larger value to be output; the waiting state control circuit controls sampling and waits till a waveform is stable; the learning state control circuit controls the time sequence of a learning state; the increment control circuit controls an increment circuit which realizes two adjacent times of sampling; the system control circuit controls a finite state machine together with other circuits; and the delay circuit realizes required delay. In the method of the invention, an entire switching period of a switch power supply is divided into five states in turn: a PWM open state, a waiting state, a learning state, a detection state and a demagnetization ending state; the five states form the finite state machine; and the detection and sampling and holding of a feedback voltage can be realized by controlling the state switching and output of the finite state machine.

Description

technical field [0001] The present invention relates to integrated circuits. More specifically, the present invention relates to a control circuit of a switching power supply chip. Background technique [0002] Switching power supplies have been widely used in various electronic devices. For safety, switching power supplies use transformer isolation, which provides isolation between the primary and secondary. In order to stabilize the system output, the system should work in a negative feedback closed-loop state. The classic approach is to use optocoupler devices and TL431 to achieve isolated feedback. But the cost of the system will increase a lot. In order to reduce costs, the auxiliary winding of the transformer has been used to realize the feedback of the power output. Of course, this method is also isolated and safe. However, many technologies cannot accurately measure the feedback voltage of the transformer, such as Randolph D.W. Shelly's US patent (US4302803) "Re...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M3/335
Inventor 周光友
Owner 深圳市矽湾微电子有限公司
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