Self-calibration soft start circuit of buck converter

Abstract

The invention discloses a self-calibration soft start circuit of a buck converter, and relates to the technical field of power supply. The self-calibration soft start circuit comprises a climbing control circuit. A first comparator in the climbing control circuit obtains and compares an output voltage feedback signal of an output voltage after the output voltage passes through a voltage division circuit and a reference signal of the in-phase input end of an error amplifier, and the output end of the climbing control circuit is connected with the enable end and the reset end of a counter through a register circuit and connected with a controller. Codes generated by the counter control the digital-to-analog converter to generate a reference voltage as a reference signal of the in-phase inputend of the error amplifier. The self-calibration soft start circuit can monitor and judge whether the output voltage rises along with the climbing of a reference signal or not in real time; if an exception occurs, the soft start process is carried out again after the exception contact is carried out even if a protection action is generated, so the effect that the soft start process exists in different scenes without generating overshoot voltage is achieved, and the safety and the reliability are higher.

Description

technical field [0001] The invention relates to the technical field of power supplies, in particular to a self-calibration soft-start circuit of a step-down converter. Background technique [0002] In consumer electronics and automotive electronics, the energy of the power consumption terminal comes from the battery terminal, and the voltage range provided by the battery terminal is about 8-20V, while the power consumption terminal is usually LED lamp beads, sensor chips, interface chips and main control chips, etc. , These electronic components and chips of different specifications have different requirements for power supply, and the working voltage range is about 3~5V. Therefore, it is necessary to use BUCK (step-down converter) chips to reduce the voltage of the battery terminal to the rated working voltage of the power supply terminal. power it. [0003] Please refer to figure 1 , the BUCK chip mainly includes the controller, the driver MN1 and the driver MN2. The con...

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Problems solved by technology

[0005] However, in automotive electronics, the output of the battery terminal is not a stable voltage, especially when the engine is just started or the working state changes suddenly, the voltage of the battery terminal will fluctuate greatly, which poses a challenge to the functional safety of the BUCK chip. It has very high requirements, especially for the stability and reliability of soft start, and the above-mentioned figure 1 When the BUCK chip with the structure shown is used in the field of automotive electronics, there are at least the following problems: If the BUCK chip outputs a large load during the start-up phase, V OUT It will not be able to follow the climbing due to the limited load capacity, so when V REF1 reaches the set reference value while the output V OUT When the load becomes light load, the voltage V of the two input terminals of the error amplifier EA1 at this time FB and V REF1 The pressure difference will be very large, so that the restart of the BUCK chip does not achieve the effect of soft start and the output overshoot occurs

It can be seen that although a soft-start circuit is added inside the existing BUCK chip, it cannot meet the functional safety and reliability requirements of automotive electronics.

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