COT-control-based ripple-compensation-based buck circuit power management chip

Abstract

The invention discloses a COT-control-based ripple-compensation-based buck circuit power management chip comprising a power input pin, an output voltage pin, a grounding pin, an enabling pin, an over-current detection pin, a feedback pin and a switch SW pin. A reference circuit module, an over-current protection module, a zero-current switching module, a control logic and soft starting module, a constant conduction time generation module, a comparator module, a ripple compensation module, a drive module, and two on-chip switching tubes are arranged inside the chip. According to the power management chip provided by the invention, ripples can be superposed at the reference voltage terminal inside the chip. Compared with the traditional method superposing the ripples with the feedback voltage sampling terminal, the provided technical scheme enables the traditional COT-control-based off-chip RC passive compensation network to be reduced; and the on-chip ripple compensation module uses the active compensation way with the pseudo inductive current ramp, so that the low resistance and capacitance are used and no accumulation error of the used compensated waveform is caused.

Description

Technical field [0001] The invention belongs to the technical field of integrated circuits, and specifically relates to a Buck circuit power management chip with ripple compensation based on COT control. Background technique [0002] Power management chips are chips that manage the power consumption of each module in the system. Some power management chips will be used in switching power supply circuits. The switching power supply circuit is defined in a broad sense as a circuit that uses semiconductor power devices as switches to transform the power supply form into another form. During the transformation, it uses an automatic control closed loop to stabilize the output and has a protection link. The switching power supply circuit generally includes a control chip and peripheral circuits. Common topological structures of switching power supply circuits include: Buck, Boost, Flyback, Forward, Half Bridge and Full Bridge. Among them, the control methods of Buck circuit include: ...

AI Technical Summary

Problems solved by technology

[0005] However, in the traditional COT-controlled Buck circuit, a resistor R is directly connected in parallel at both ends of the inductor L 3 and capacitance, C 1 、C 2 The RC passive compensation method will require larger capacitors and resistors

However, if a triangular wave proportional to the inductor current is directly generated on-chip to compensate the ripple, due to the influence of the process, it cannot be guaranteed to return to zero every cycle, and it is easy to generate integral errors.

At the same time, the traditional Buck circuit acts under DCM, and the inductor current I L When it falls and crosses zero, it fails to turn off the lower side tube Mn in time, so that the inductor current I L Reverse current occurs, which greatly increases the system loss, and lacks to prevent the inductor current I L Excessive overcurrent protection function, low system safety

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