Bootstrap circuit and power chip

Abstract

The invention discloses a bootstrap circuit and a power chip. The bootstrap circuit comprises a bootstrap capacitor, a switch unit, a switch control unit and a pull-up unit, the first pole of the bootstrap capacitor serves as the voltage reference end of the bootstrap circuit, the second pole of the bootstrap capacitor is connected with the second end of the switch unit and the first end of the pull-up unit and serves as the voltage output end of the bootstrap circuit, and the first end of the switch unit serves as the voltage input end of the bootstrap circuit. The control end of the switch unit is connected with the output end of the switch control unit and the second end of the pull-up unit, and the input end of the switch control unit is connected with the first voltage input end. Thebootstrap circuit can improve the accuracy of the bootstrap circuit and reduce the power consumption of the power chip where the N-type transistor is located. Besides, a Schottky diode can be prevented from being arranged in the bootstrap circuit, so that a mask plate for manufacturing the power chip can be prevented from being added when the bootstrap circuit is integrated in the power chip, andthe cost for manufacturing the power chip is reduced.

Description

technical field [0001] Embodiments of the present invention relate to the technical field of power supplies, and in particular to a bootstrap circuit and a power chip. Background technique [0002] With the development of science and technology, the power and integration requirements of power management chips are getting higher and higher. Since the electron mobility of N-type transistors is 2-4 times higher than that of P-type transistors, in high-power chips, N-type transistors can be used as switches of power devices to achieve higher power per unit area of ​​power chips , the cost is lower. When an N-type transistor is used as a high-side (high-side) switch of a power chip, usually the gate driving voltage of the N-type transistor can be increased through a bootstrap circuit to control the on-off of the transistor. figure 1 It is a structural schematic diagram of an existing bootstrap circuit. Such as figure 1 As shown, the bootstrap circuit includes a Schottky diode...

AI Technical Summary

Problems solved by technology

Since the bootstrap circuit includes the Schottky diode SD1, when it is integrated into the power chip, the level of the process will be increased, thereby increasing the mask plate for making the power chip, and thus increasing the cost of making the power chip

Moreover, the conduction voltage drop of the Schottky diode SD1 is relatively large. When charging the bootstrap capacitor Cp1, the potential of the output terminal OUT of the bootstrap circuit is lower than the potential of the gate drive power supply VCC of the N-type transistor, which reduces the voltage of the N-type transistor. The gate drive voltage of the transistor also makes the internal resistance of the N-type transistor driven by it relatively large, which increases the power consumption of the power chip

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