Serial-connection type voltage adjusting circuit

Abstract

The invention discloses a serial-connection type voltage adjusting circuit, which comprises a typical serial-connection voltage adjusting circuit body and a logic control circuit. The logic control circuit consists of a band-gap reference voltage input end and a ramp signal voltage input end, ramp signal voltage is gradually changed between zero and power voltage, an output end of the logic controller is connected with a positive input end of an error amplifier in the typical serial-connection voltage adjusting circuit body, when the ramp signal voltage is lower than band-gap reference voltage, voltage outputted by the logic control circuit is the ramp signal voltage, and when the ramp signal voltage is higher than the band-gap reference voltage, the voltage outputted by the logic control circuit is the band-gap reference voltage. By the aid of the serial-connection voltage adjusting circuit, peak impact can be avoided at the started moment.

Description

technical field [0001] The invention relates to analog power supply technology, in particular to a series voltage adjustment circuit. Background technique [0002] The voltage adjustment circuit is commonly known as the voltage regulator circuit, and its function is to obtain a stable DC voltage from an unsteady power supply voltage. With the continuous development of analog hybrid circuits, the circuit system requires more and more precise voltage and current references. In order to control the voltage, the most common design of modern circuits is the voltage adjustment circuit. The general voltage adjustment circuit is divided into parallel and series according to the structure. . The traditional series voltage regulator circuit controls the stable output voltage by constantly adjusting the power tubes connected in series between the input and output. [0003] figure 1 Shown is a typical series voltage adjustment circuit. The voltage adjustment power transistor T1 is an...

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Problems solved by technology

[0005] When the typical series voltage adjustment circuit is started, the reference voltage Vref is used to control the conduction of the NMOS transistor voltage adjustment power transistor T1 through the error amplifier 10. Since the resistance sampling feedback voltage transient of the negative input terminal of the error amplifier 10 is zero, and the positive The reference voltage Vref at the input terminal can be quickly in place, and the gain of the error amplifier 10 is very high, so there will be a transient high voltage impact on the grid of the NMOS voltage adjustment power transistor T1. At this time, the NMOS voltage adjustment power transistor T1 is equivalent to a switch, and the power supply voltage Vcc is immediately transmitted to the source of the NMOS voltage adjustment power transistor T1 to output a stable voltage Vout. The output stable voltage Vout transiently responds to a spike, and then slowly enters a stable state through adjustment. This spike is inevitable at the moment of startup. , it is prone to over-voltage, over-power damage, and affects the reliability of the voltage regulation circuit

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