A buck constant voltage drive circuit and buck constant voltage driver

Abstract

The invention relates to a BUCK constant-voltage driving circuit and a BUCK constant-voltage driver. The BUCK constant-voltage driving circuit comprises a voltage output module, a control module, an overcurrent reference generation module, an overcurrent protection module, a constant-voltage control module, and a PWM (pulse width modulation) control module, wherein the control module is used for outputting a control signal to control the conduction and disconnection of a main switch tube in the voltage output module; the overcurrent reference generation module is used for obtaining the conduction time of the main switch tube according to the control signal, and compensating the overcurrent reference voltage of low input voltage; the overcurrent protection module is used for outputting a feedback signal to the control module according to the overcurrent reference voltage, and performing overcurrent protection on the voltage output module under the condition of loads; the constant-voltage control module is used for sampling output voltage, and outputting a constant-voltage adjusting signal according to the output voltage and the output reference voltage; the PWM control module is used for outputting the feedback signal to the control module according to the constant-voltage adjusting signal, adjusting the peak current in the voltage output module, and adjusting the output voltage into constant voltage. The BUCK constant-voltage driving circuit has the advantages that on the basis of maintaining low cost in the prior art, the high and low-voltage driving capacities are more approximated; under the condition of light load, the peak current can be decreased, and the light-load response and no-load power consumption characteristics are optimized.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a BUCK constant voltage drive circuit and a BUCK constant voltage driver comprising the drive circuit. Background technique [0002] The typical application of the prior art BUCK constant voltage drive circuit is as follows: figure 1 shown. Its working principle is as follows: when the CLK generator sends a set signal, the high-voltage MOS transistor M1 is turned on by the drive module, the high-voltage MOS transistor M1 is turned on, the current of the inductor L will increase with a fixed slope, and the Vcs voltage will also increase accordingly. When the current of the inductor L increases to make Vcs equal to the internal comparison voltage Vref of the controller, the drive module will turn off the MOS transistor M1 to cut it off, and at this time Vs will quickly drop to -V D1 , the current on the inductor L drops with a fixed slope through the diode D1, and at the same tim...

AI Technical Summary

Problems solved by technology

[0011] It can be seen from the above formula that the peak current increases with the increase of the input voltage Vin, resulting in a significantly weaker drive capability at low input voltage than at high input voltage;

[0012] 2) For BCM and DCM working modes, the relationship between output power, peak current Ipk and working frequency F is: Since the peak current of the existing technology does not decrease under light load or even no-load conditions, the light-load frequency is too low, not only the response is slow, but also the no-load power consumption is large

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