Current monitoring circuit with accurate current-limit function

Abstract

The invention discloses a current monitoring circuit with the accurate current-limit function. The current monitoring circuit with the accurate current-limit function comprises an operational amplifier, wherein a forward input end and a reverse input end of the operational amplifier are respectively connected with a resistor in series, the resistors are symmetrical to each other, the reverse input end of the operational amplifier is connected to the output end of the operational amplifier in series through a resistor R1 and a capacitor C1, the symmetrical resistors which are connected with the operational amplifier in series are further in ground connection, an output filtering loop is formed by an inductor L1 and a capacitor CL, a load RL is connected to the capacitor CL in parallel, and is connected with a feedback resistor Rf in series, the feedback resistor Rf is connected to the forward input end of the operational amplifier am1 in series, and is used for carrying out sampling on current change signals of the output filtering loop, and the sampled current change signals are converted into voltage signals to be input into the forward input end of the operational amplifier. The current monitoring circuit with the accurate current-limit function directly detects output current signals, the output current signals are converted into the voltage signals through the resistors, and compared with reference voltage, the level of an enabling end can be reduced through output overturn of the operational amplifier, and short-circuit protection is achieved.

Description

Technical field [0001] The invention belongs to the technical field of protection of power supply output short-circuit or over-current conditions, and relates to a current monitoring circuit with accurate current limiting. Background technique [0002] The current implementation method of power short-circuit protection is mainly the pre-input current sampling protection. [0003] The front-stage input current sampling protection is a protection method for input over power. Such as figure 1 As shown in the circuit, it realizes the output control of the PWM controller by collecting the primary peak current signal of the main transformer. When the current in the input line is too large, that is, when the peak current detection signal is greater than 1V, the current detection comparator will output a high level, which will cause the U1 (OR gate) output to be high, so that the transistor N1 is turned on and the output Pull it low to 0, the Q1 tube cannot be turned on, and finally the ...

AI Technical Summary

Problems solved by technology

Due to the detection of the previous stage current, when the input voltage increases, the power consumption of the short circuit protection will increase exponentially, and the precise current limiting protection of the output current cannot be realized

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