Short circuit protection circuit for audio power amplifier

Abstract

The invention relates to a short circuit protection circuit for an audio power amplifier. In the presence of two diodes in the circuit, a power tube does not have a conducting condition under the signal currents of different semi revolutions, the diodes isolate a voltage dividing loop when a load is short-circuited, the power tube is conducted when the pressure drop on an emitter resistor of the power tube reaches the conduction voltage of a short circuit detection tube and short circuit information is transmitted. A short circuit detection circuit is connected to the output stage of the power amplifier and the emitter resistor of the power tube is taken as a current detection device. Short circuit detection information is transmitted to a single steady state circuit for processing, temporary steady state is entered for 2 seconds after momentary triggering and temporary steady state level is used for controlling silence of the input end of the power amplifier; simultaneously, the short circuit information is transmitted to a central processing unit (CPU), the CPU drives a vacuum fluorescent display (VFD) to prompt the short circuit information and a high level is transmitted to switch off a power switch if three times of short circuit information is detected continuously within eight seconds. The practical use of the circuit disclosed by the invention indicates that the circuit is effective and reliable.

Description

[0001] technical field [0002] The invention relates to a short-circuit protection circuit, in particular to a short-circuit protection circuit for a power amplifier output terminal in an audio power amplifier. [0003] Background technique [0004] With the continuous development and maturity of the audio industry, people's requirements for audio products continue to increase. Not only the sound quality is better, the function is more, the appearance is fashionable, and the operation is humanized, but there are also new requirements in terms of reliability, including load short circuit during work. All phenomena must not be damaged, which may occur during wiring operations, or may occur when there is a problem with the speaker. There are several shortcomings in the previous short-circuit protection circuit: 1. The short-circuit detection and over-current detection may be confused, and it may be misjudged as a short-circuit during high-power operation; 2. It can only withs...

AI Technical Summary

Problems solved by technology

[0004] With the continuous development and maturity of the audio industry, people's requirements for audio products continue to increase. Not only the sound quality is better, the function is more, the appearance is fashionable, and the operation is humanized, but there are also new requirements in terms of reliability, including load short circuit during work. The phenomena can not be damaged, which may occur during the wiring operation, or may also occur when there is a problem with the speaker

There are several shortcomings in the previous short-circuit protection circuit: 1. The short-circuit detection and over-current detection may be confused, and it may be misjudged as a short-circuit during high-power operation; 2. It can only withstand short-term short-circuits, and long-term short-circuits are eventually accumulate or burn

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