Slope compensation circuit and backlight display device

By designing a two-stage slope compensation circuit, a quadratic function relationship between the slope compensation current and the conduction time of the switching transistor is realized. This solves the problem that the linearly increasing compensation current in the existing technology cannot meet the compensation strength under high transfer ratios, and ensures the stability and reliability of the circuit under a wide range of parameter variations.

CN121708865BActive Publication Date: 2026-05-26SHENZHEN LOWPOWER SEMICON CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
SHENZHEN LOWPOWER SEMICON CO LTD
Filing Date
2026-02-13
Publication Date
2026-05-26

AI Technical Summary

Technical Problem

In existing slope compensation circuits, the slope compensation current is linearly related to the switching transistor's on-time. When the transfer ratio is extremely high, the linearly increasing compensation current is insufficient to meet the compensation strength requirements, resulting in a significant extension of the switching transistor's on-time and affecting circuit stability.

Method used

A two-stage slope compensation circuit design is adopted. The first stage of slope compensation is formed by the first current generation module and the first current mirror module. The mirror current has a linear function relationship with the conduction time of the switching transistor. It is further used as the input of the second current generation module to drive the second current generation module to generate a second current. The slope compensation current output by the second current mirror module has a quadratic function relationship with the conduction time of the switching transistor.

Benefits of technology

In high-transfer-ratio scenarios, the rate of change of the ramp compensation current increases significantly with the conduction time, meeting the compensation strength requirements, ensuring stable operation of the circuit under high-transfer-ratio conditions, simplifying circuit design, and avoiding reliability risks caused by high-voltage feedback.

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    Figure CN121708865B_ABST
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Abstract

The present application provides a slope compensation circuit and a backlight display device. The slope compensation circuit includes a first current generation module, a first current mirror module, a second current generation module and a second current mirror module. The first current generation module is electrically connected to the first current mirror module, and the second current generation module is electrically connected to the first current mirror module and the second current mirror module respectively. The first current generation module generates a first current, and the first current mirror module outputs a mirror current according to the first current. The mirror current has a linear function relationship with the conduction time of the switching transistor. The second current generation module generates a second current according to the mirror current, and the second current mirror module outputs a slope compensation current according to the second current. The slope compensation current has a quadratic function relationship with the conduction time of the switching transistor. The present application effectively solves the problem that when the conversion ratio of the existing slope compensation circuit is extremely large and the conduction time of the switching transistor is significantly extended, the linearly increasing compensation current is difficult to meet the compensation intensity requirement.
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