Input stage protection circuit
A technology for protecting circuits and input stages, applied in emergency protection circuit devices, circuit devices, emergency protection circuit devices for limiting overcurrent/overvoltage, etc., to achieve the effect of wide application range and small area
Inactive Publication Date: 2012-10-03
WUXI YOUDA ELECTRONICS
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[0005] The purpose of the present invention is to provide an effective protection circuit for input stage protection. When the input signal of the internal input stage of the integrated circuit is too large or an abnormal input signal occurs, the protection circuit provides amplitude limiting and protection for the internal input stage of the protected circuit. It solves the leakage current problem of using a Zener diode as a limiter protection in a circuit that requires a small signal amplitude at the input stage, and improves the reliability of the protection circuit itself
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[0012] Such as image 3 An input stage protection circuit is shown, which includes NPN transistor Q1, N diodes D 1 -D N and resistor R1; the collector of the NPN transistor Q1 is connected to the input terminal Vin, and the emitter is grounded; the resistor R1 is connected between the base and the emitter of the NPN transistor Q1; the N diodes D 1 -D N Connected in series between the base and collector of NPN transistor Q1, diode D 1 The anode of the NPN transistor Q1 is connected to the collector, and the diode D N The cathode of the NPN transistor Q1 is connected to the base.
[0013] Among them, D 1 -D N works like figure 1 in the Zener diode, so D 1 -D N The number of series connection depends on the protection or limiting voltage value required by the input stage of the protected circuit, that is, the voltage regulation value V Z It is equal to the sum of the forward voltage drop of n diodes plus the forward voltage drop of the emitter junction of the first NPN ...
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The invention discloses an input stage protection circuit, which comprises an NPN triode Q1, N diodes D1-DN and a resistor R1, wherein a collecting electrode of the NPN triode Q1 is connected with the input end Vin, an emitting electrode is grounded, the resistor R1 is connected between a base electrode and the emitting electrode of the NPN triode Q1, the N diodes D1-DN are connected in series between the base electrode and the collecting electrode of the NPN triode Q1, a positive electrode of the diode D1 is connected with the collecting electrode of the NPN triode Q1, and a negative electrode of the diode DN is connected with the base electrode of the NPN triode Q1. The input stage protection circuit has the advantages that an effective protection effect is realized when the circuit input stage generates abnormal input signals, the protection voltage can be set according to the protection circuit requirements, in addition, the VZ value can be set to be lower than 5.8V on the premise of not influencing the normal work and the performance of the circuit, the application range is wider than that the ordinary diode, the required area is also smaller, and in addition, the additional territory layer and process steps are not needed.
Description
technical field [0001] The invention relates to a protection circuit providing protection for an internal input stage of an integrated circuit, which belongs to the technical field of semiconductor manufacturing. Background technique [0002] For the input stage of many integrated circuits, it is inevitable that the input signal is too large or other abnormal signal pulses often appear. After such an excessive or abnormal input signal is amplified, it will inevitably lead to instability inside the circuit, or directly lead to Burnout of the input stage renders the circuit ineffective. In this case, a zener diode is generally added as the protection of the input stage. Designers can design different voltage regulation values and flexibly control the protection point according to the needs of different circuits, so that even if the input stage is too large The input signal will also be limited by the Zener tube, or when there is an abnormal input signal, it can also be disc...
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IPC IPC(8): H02H9/04
Inventor 苏卡马晓辉
Owner WUXI YOUDA ELECTRONICS