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A zero-temperature adjustable acot charging current circuit

A charging current and circuit technology, applied in the field of switching power supply, can solve the problems of limiting the application of ACOT switching power supply, affecting the stability of the chip system, and unable to realize frequency conversion control.

Active Publication Date: 2022-05-17
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These shortcomings will cause the operating frequency of the system to change when the switching power supply chip works in different environments, thus affecting the stability of the chip system
[0003] In addition, for frequency conversion application scenarios (such as: LED drive), the traditional ACOT charging current is only related to the internal circuit of the chip. After the chip is packaged, the system switching frequency is fixed, and frequency conversion control cannot be realized, which greatly limits the application of ACOT switching power supply.

Method used

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  • A zero-temperature adjustable acot charging current circuit
  • A zero-temperature adjustable acot charging current circuit
  • A zero-temperature adjustable acot charging current circuit

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Embodiment Construction

[0019] Below in conjunction with accompanying drawing, technical solution of the present invention is described in detail:

[0020] The ACOT charging current circuit that the present invention proposes is as figure 1 shown. When the internal enable signal EN is low, the PTAT current path is disconnected, the ACOT module does not work, and the drain terminal of the first NLDMOS transistor is resistant to high voltage, which protects the internal circuit; when EN is turned high, the first NLDMOS transistor works in the linear region , its on-resistance is very small and can be ignored, according to the triode V BE Theoretical expression for voltage variation with temperature:

[0021]

[0022] where V g0 is the silicon bandgap voltage at zero temperature, T r is the reference temperature, V Tr is the thermal voltage at the reference temperature, η is a constant related to the process, x represents the temperature coefficient of the collector current flowing through the t...

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Abstract

The invention belongs to the technical field of switching power supplies, and in particular relates to an ACOT charging current circuit with adjustable zero temperature. The present invention utilizes the negative temperature characteristics of the base-emitter (BE junction) voltage of the triode, respectively utilizes the mode of series connection and parallel connection of the resistance and the BE junction of the triode to generate a positive temperature coefficient current and a negative temperature coefficient current, and by reasonably setting the current coefficient, A zero temperature coefficient charge current can be achieved. The beneficial effect of the invention is that it overcomes the disadvantages of the traditional ACOT that the charging current varies with temperature and cannot be adjusted after forming into pieces. The ACOT charging current circuit not only generates a temperature-independent current, but also can adjust the size of the internal charging current by changing the size of the external resistor.

Description

technical field [0001] The invention belongs to the technical field of switching power supplies, and in particular relates to an ACOT charging current circuit with adjustable zero temperature. Background technique [0002] With the continuous development of the electronics industry, the demand for high-performance power management chips in electronic products is also increasing. Constant On-time (Constant On-time, COT) controlled Buck converters are favored for their advantages of simple structure, high efficiency and fast response. The adaptive constant on-time (Adaptive Constant On-time, ACOT) technology developed on the basis of the COT circuit, relying on its pseudo-constant frequency characteristics, can eliminate the electromagnetic interference (Electromagnetic Interference, EMI) problems make ACOT switching power supply more widely used. The core of the ACOT circuit to achieve constant frequency is to generate a charging current circuit that is positively related t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G05F1/567
CPCG05F1/567Y02B70/10
Inventor 周泽坤龚州任航王卓张波
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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