Control technique for switch power supply, inductance and current

Abstract

The invention provides a switch electrical source inductance current control technique which uses an intelligent closing time controller to adjust closing time of a power switch automatically for controlling the current in the inductance opening time, an input end of the intelligent closing time controller connects with a leakage end of the power switch, an output end of the intelligent closing time controller connects with an enable pin of a drive unit, uses the current size in the inductance opening time for controlling the closing time of the inductance, controls the current in the inductance opening time in an appointed value. The technique provided by the invention has advantages that: the technique can control the current in the power switch opening time, and control the current in the power switch closing time; a current detecting resistance only flows the current in the power opening time for increasing the system efficiency; a control mechanism does not connect with the input voltage that can improve the input voltage application range of the system, reduce cost, and compensate infection of the input voltage to an average current, make the LBD keeping constant brightness in various input voltage.

Description

technical field [0001] The invention belongs to a switching power supply technology, in particular to a switching power supply inductor current control technology. Background technique [0002] Switching power supply has high energy conversion efficiency, reliable performance, and flexible control, and it occupies an increasingly important position in power supply applications. In the control method of the switching power supply, the control of the inductor current is very important, especially when the inductor is directly used as a current-driven device, such as LED (light-emitting diode) drive. figure 1 It is a structure commonly used in LED driving. It consists of power switch M1, light-emitting diode, inductor L1, and freewheeling diode D3. The power stage is composed of current detection resistor R2, oscillator I3, current limit comparator I2 and power switch drive unit I4. A control mechanism is formed, wherein the output of the oscillator I3 is connected to the enab...

AI Technical Summary

Problems solved by technology

[0006] 1) The sense resistor is always connected in series with the inductor, resulting in power loss and reduced efficiency;

[0007] 2) The detection resistor is directly connected to the input voltage, so that the specific control mechanism can only be applied to a certain input voltage range; at the same time, in the case of high input voltage, the cost of realizing the control mechanism is high;

[0008] 3) Due to the delay of the drive unit, the maximum and minimum values ​​of the inductor current are different under different input voltages, resulting in inconsistent brightness of the LEDs

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