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Protective circuit

A technology for protecting circuits and current limiting circuits, which is applied in the direction of amplifier protection circuit layout, etc., and can solve problems such as rising

Inactive Publication Date: 2014-04-02
E CMOS CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although this method can reduce the large current caused by the short circuit of the operational amplifier, it cannot completely avoid the possibility of damage. The main reason is that if the short circuit problem of the operational amplifier lasts for a long time and is not resolved, even if the current becomes smaller, the temperature may continue to rise to Exceeding the temperature that the chip can withstand, in short, this method only slows down the rate of temperature rise, and the chip is still exposed to the risk of being burned

Method used

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Embodiment Construction

[0035] Please refer to figure 1 as shown, figure 1 It is an embodiment of the present invention applied to a protection circuit of an operational amplifier. Generally speaking, the internal circuit design of the operational amplifier can be roughly divided into three large blocks as the input stage circuit, the gain stage circuit and the output stage circuit. The exterior of the operational amplifier includes an output terminal Vo, a positive input terminal, and a negative input terminal. The input terminal, a positive voltage source +VDD and a negative voltage source -VDD, circuits at all levels are formed by coupling multiple transistors, and different types of operational amplifiers have different structures, since this part belongs to the present invention Those of ordinary skill in the art know that, therefore, in order to simplify the length, this description only describes the scope of application of the protection circuit when it is written, and does not describe the ...

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Abstract

The invention provides a protective circuit, which is used for preventing an operational amplifier from being damaged due to short circuit by mistake, and at least comprises a temperature detection circuit, a control circuit and a pair of second current limiting circuits, wherein the temperature detection circuit produces an over-temperature signal when the temperature is over a preset value, or produces a normal signal when the temperature is lower the critical value of the preset temperature; the control circuit sends a control signal according to the over-temperature signal, and cuts off the current output path of the operational amplifier according to the over-temperature signal or conducts the current output path of the operational amplifier according to the normal signal; the second current limiting circuits are conducted by the control signal, and are used for limiting the current of the operational amplifier to be output into second current. According to the invention, the current output of the operational amplifier can be dynamically adjusted, so that the potential risks resulting in damage, which is caused by the short circuit, can be avoided.

Description

technical field [0001] The invention relates to a protection circuit, in particular to a protection circuit applied to prevent an operational amplifier (Operational Amplifier) ​​from being damaged due to a false short circuit. Background technique [0002] Generally speaking, an operational amplifier (or called an operational amplifier) ​​is often used as a component output buffer (Buffer) in a chip. When the output terminal of the operational amplifier is short-circuited (Short) due to negligence, the operation The amplifier will produce a very large current output due to the short circuit effect. This large current may increase the overall temperature of the chip, and even cause the chip to malfunction or burn out. [0003] A currently known short-circuit protection method limits the output current of the operational amplifier when the temperature exceeds a predetermined temperature threshold, reducing the probability of failure or burnout caused by excessive chip temperat...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03F1/52
Inventor 吴佳龙贺仲达
Owner E CMOS CORP
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