Control circuit of DC/DC boost system
A technology of boosting system and control circuit, applied in the direction of control/regulating system, electrical components, regulating electrical variables, etc., can solve the problems of high operating frequency of the system, inability to achieve better light load efficiency, etc. Effect
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Embodiment 1
[0044] see image 3 , image 3 Shown is a schematic diagram of a preferred embodiment of the control circuit of the DC / DC step-up system of the present invention. As shown in the figure, the control circuit of the DC / DC step-up system includes a first voltage dividing resistor RFB1, a second voltage dividing resistor RFB2, a voltage stabilizing capacitor C1 for V1, a voltage stabilizing capacitor C2 for V2, Voltage source DC, inductor L1, first transistor Q1, second transistor Q2, constant on-time module, gating module T1, oscillator module OSC, error amplifier module EAMP, comparator module PWMCMP, logic control module LOGIC, drive module DRIVER and current zero-crossing comparison module ZCDCMP; the voltage V1 is the voltage signal at the input end of the control circuit, and the voltage V2 is the voltage signal at the output end of the control circuit, and the voltage V1 is usually smaller than the voltage V2.
[0045] Specifically, the inductor L1 is connected between th...
Embodiment 2
[0065] In the embodiment of the present invention, by adding an on-off pre-control module, when the current flowing through the first transistor Q1 is greater than a preset current threshold, the on-off pre-control module controls the gating module T1 An output of the constant on-time module is received. That is, the conduction time of the first transistor Q1 must not only satisfy TON>=TOSC*(V2-V1) / V2, but also satisfy that the conduction current of the conduction Q1 reaches a set current value.
[0066] Specifically, the on-off pre-control module includes a logic gate and a current monitoring module; the current detection module includes a zeroth transistor Q0, a comparator circuit CLCMP and a current source IOC; an input terminal of the logic gate is connected to the The output terminal of the constant on-time module, one input terminal of the logic gate is connected to the output terminal of the comparator circuit CLCMP, and the zeroth transistor Q0 is a mirror transistor o...
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