A grid-source voltage undervoltage detection circuit for power tubes suitable for dc-dc converters

Abstract

A power tube grid-source voltage undervoltage detection circuit suitable for DC-DC converters, including a voltage sampling module, a time reference generation module and a logical operation module, the voltage sampling module is used to sample the grid signal of the power tube and output the sampling signal , the delay time between the sampling signal and the grid signal of the power tube is T1; the time reference generation module is used to delay the control signal of the power tube for a delay time of T2 to generate a narrow pulse signal, and the narrow pulse signal is used as a time reference Signal, the control signal of the power tube is in phase with the gate signal of the power tube; the logic operation module is used to compare the sampling signal and the time reference signal, and an undervoltage signal is generated when T1 is greater than T2. The invention uses the time reference signal to compare the sampling voltage of the power tube, and can detect whether the high-side power tube and the low-side power tube in the DC-DC converter are undervoltage, and has the characteristics of fast and accurate, and the undervoltage signal returns to control the power The tube can improve the stability and efficiency of the DC-DC converter.

Description

technical field [0001] The invention belongs to the technical field of electronic circuits, and relates to an undervoltage detection circuit for detecting whether the grid-source voltage of a power tube in a DC-DC converter is undervoltage, which can detect the high-side power tube and low-side power of the DC-DC converter. Tube. Background technique [0002] Efficiency is one of the important indicators to measure the performance of DC-DC converter, which can be measured by the ratio of converter output power to input power. Taking the Buck converter as an example, there are many factors that affect the efficiency of the Buck converter, such as the switching loss generated during the turn-on and turn-off of the power tube, the conduction loss generated during the conduction process of the power tube, the magnetic core loss of the inductor, and the internal The static power consumption of the circuit and so on. like figure 1 As shown, the Buck converter has the highest wo...

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Problems solved by technology

[0010] In view of the efficiency attenuation problem that may exist in the working process of the above-mentioned Buck converter due to the undervoltage of the high-side power transistor gate-source voltage, and the generation of a reference voltage in the floating power rail in the traditional undervoltage detection method leads to high-frequency and high-voltage applications. For the problem of limited speed and precision, the present invention proposes an undervoltage detection circuit, which uses a time reference detection method to detect the high-side power tube or low-side power tube gate signal by comparing the gate signal with the time reference signal Whether the grid-source voltage of the low-side power tube is undervoltage is suitable for DC-DC converters; when the undervoltage detection circuit proposed by the present invention is used to detect the undervoltage of the high-side power tube, the undervoltage signal is used as an enabling signal to turn off The high-side power tube is used until the end of the undervoltage, which can avoid unnecessary conduction loss

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