Back porch sampling circuit and method for sampling back porch falling edge voltage

A sampling circuit and voltage technology, applied in the direction of measuring current/voltage, measuring electrical variables, measuring devices, etc., can solve the problems of slow transient response, low precision of constant voltage and constant current, etc. The effect of voltage constant current accuracy

Inactive Publication Date: 2012-12-26
FUZHOU ROCKCHIP SEMICON
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  • Abstract
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Problems solved by technology

[0014] The present invention provides a back-porch sampling circuit and a method for sampling the falling-edge voltage of the back-porch, so as to achieve the purpose of improving the accuracy of voltage regulation and constant current and improving the transient response speed, so as to solve the existing problems in the above-mentioned primary side feedback type flyback switching power supply. The problem of low precision of voltage regulation and constant current and slow transient response

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  • Back porch sampling circuit and method for sampling back porch falling edge voltage
  • Back porch sampling circuit and method for sampling back porch falling edge voltage
  • Back porch sampling circuit and method for sampling back porch falling edge voltage

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Embodiment Construction

[0051] The core idea of ​​the present invention is that the back shoulder sampling circuit used includes: a counting circuit, a detection circuit and a calculation circuit. The detection circuit can detect the time T from when the switching element is turned off to the nth zero-crossing point of the ringing wave vcn or the time T at which the nth valley occurs van ; The calculation circuit can be based on the T vcn or T van Accurately calculate the time T from when the switching element is turned off to the falling edge of the ringing wave back dis , and then from switching element off after T dis The measured voltage is the exact voltage on the falling edge of the back porch V B , which passes through the resistor R 1 and R 2 After the voltage is divided, it is the sampling voltage V s . because T dis The calculation of is directly calculated by the back-porch sampling circuit, and the voltage V at the moment of the falling edge of the back-porch B and the peak curr...

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Abstract

The invention discloses a back porch sampling circuit and a method for sampling back porch falling edging voltage. The back porch sampling circuit comprises a counting circuit, a detection circuit and a computing circuit, wherein the counting circuit is used for counting zero passage times and bottom number of a ring wave on a high frequency transformer auxiliary winding; the detection circuit is used for detecting time tvcn from turn-off of a switch element to nth zero passage of the ring wave or time tvan from the turn-off of the switch element to nth bottom of the ring wave; the computing circuit is used for figuring out time Tdis from the turn-off of the switch element to beginning of back porch falling edge of the ring wave; and n is nonnegative integer. According to the back porch sampling circuit and the method for sampling back porch falling edging voltage, the back porch sampling circuit can rapidly obtain control signals with high-precision stable voltage and constant current, is not influenced by temperature and can rapidly follow change of load and electric supply voltage, so that precision for stable voltage and constant current can be improved, and the transient response speed can be increased.

Description

technical field [0001] The invention relates to a detection technology of a voltage stabilizing and constant current control loop in an AC-DC flyback switching power supply integrated circuit, in particular to a back porch sampling circuit and a method for sampling the back porch falling edge voltage. Background technique [0002] At present, the primary-side feedback type AC-DC flyback integrated switching power supply is mostly used in LED lighting drivers and offline charging adapters. With the large-scale application of LED lighting, in order to prolong the service life of LEDs, ensure the uniformity of brightness in large-area applications, and reduce the malfunction of protection circuits caused by LED brightness changes caused by temperature changes, over-current, over-temperature and over-voltage, etc., It is necessary to improve the voltage regulation and constant current precision of its switching power supply. For the off-line switching power supply of portable e...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R19/00G01R19/175G01R19/17
Inventor 王新成施乐宁
Owner FUZHOU ROCKCHIP SEMICON
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