Control system for Cuk-type switching power supply

Abstract

The invention relates to a control system for a Cuk-type switching power supply. On the basis of a single-period control circuit, a III compensating network and a feedback circuit are additionally arranged. An output voltage Vo is divided by the feedback circuit to generate feedback signals VFB. The III compensating network comprises an error amplifier EA, resistors R1, R2 and R3 and capacitors C11, C22 and C33, the in-phase end of the error amplifier EA is connected with the feedback signals VFB, the opposite-phase end of the error amplifier EA is connected with a reference voltage VREF through the resistor R1, the resistor R3 is connected with the capacitor C33 in series to be bridged to the two ends of the resistor R1, the resistor R2 is connected with the capacitor C22 in series to be connected with the capacitor C11 in parallel, and the two ends of the parallel connection part are bridged between the output end and the opposite-phase end of the error amplifier EA. The output of the error amplifier EA is compared with the output of an integral circuit in the single-period control circuit, and the duty ratio generated by comparative results controls connection and disconnection of a power tube in the Cuk-type switching power supply.

Description

technical field [0001] The invention relates to a DC-DC switching power supply, in particular to a control system of a Cuk (Cuk) switching power supply inside an integrated circuit, and belongs to the field of microelectronic technology. Background technique [0002] Organic Light Emitting Diode OLED (Organic Light Emitting Diode OLED) has the characteristics of softness, transparency, clear picture quality, energy saving and environmental protection, etc. It is regarded as the most potential next-generation new flat-panel display technology. OLED display panels need a positive power supply voltage and a negative power supply voltage for power supply, so the design of negative voltage chips has become the mainstream trend in this field. The input and output voltage direction of the Cuk circuit has the advantages of low output voltage and current ripple and high efficiency. At the same time, the Cuk circuit also has very good anti-noise and anti-interference capabilities, so ...

AI Technical Summary

Problems solved by technology

However, there are two inductors and capacitors in the power stage of the traditional Cuk-type circuit structure, and the small-signal model is more complicated

Existing control circuits ( figure 1 ) is a one-cycle (One-cycle) control method, although the circuit can be unconditionally stable, but this control method has obvious defects: one-cycle control is a non-linear large signal pulse width (Pulse Width Modulation PWM) modulation method , it is not a closed-loop control system in a strict sense. The control signal has limited ability to correct the output voltage. When the load changes, the output voltage will change greatly, and the load regulation of the circuit is extremely poor (in figure 1 When the medium load current jumps, the output voltage will change greatly)

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