| In the developing era,people’s demand for portable electronic devices is increasing day by day.With the growth of demand and the rapid development of products,the integration and complexity of the chips in the equipment have also been greatly improved with the diversification of equipment functions.The current limiting circuit is an important part of realizing diversified power supply control.With the improvement of the country’s comprehensive strength,the performance requirements for aerospace equipment used in the universe are also getting higher and higher,and only integrated chips with deeper nano-technology can meet the performance indicators.However,with the reduction of process size,the sensitivity of integrated circuits to radiation in space has increased,especially to a series of problems caused by high-energy particles contained in radiation.It is known that the single event effect has generally existed in in integrated circuits.Therefore,this article takes improving the radiation resistance of the current limiting circuit as the starting point,and effectively targets the soft errors that may occur in the chip circuit,and strengthens the circuit against radiation.How the single event effect occurs and its impact on integrated circuits is analyzed in this thesis,and on this basis,it is reinforced at the circuit level.This paper describes the relevant current detection circuits,and proposes a programmable current limiting circuit for the shortcomings of the existing current limiting circuits.The function of the circuit can be roughly divided into three types according to the size of the load current according to the working state: the small current situation,the current situation near the threshold point,and the high current load situation.1.In the case of small current,it can be assumed that the circuit is in a no-load working state.When there is no load,the replica amplifier can turn off the PMOS tube it controls,and the input of the current limit amplifier is low.At this time,the current limit amplifier stops working,and the gate of the power tube is pulled down through the switch tube controlled by the current source,both the replicable amplifier and the current-limiting amplifier work in the nonlinear region.2.When the load current is near the set threshold current,at this time,the SET terminal voltage is about 1.24 V,the current flowing through RSET is 1/1080 times the load current,and the PMOS tube controlled by the replica amplifier can work in the saturation region.The power tube controlled by the current limiting amplifier is at the critical point of the linear region and the saturation region.Both amplifiers work in the linear region at this time.At this time,the gain of the loop is the largest,and the working conditions are adjusted.3.In the case of a short circuit,the gate of the power tube is controlled by the logic monitoring circuit at the OUT end.When the short circuit occurs,the gate of the power tube is pulled up,so that the logic control circuit relinquishes control and ensures that the authority is completely released after the loop is established.At this time,the replicable amplifier works in the nonlinear region,and the current-limiting amplifier works in the linear region.This paper uses Hua Hong 0.35 um BCD process to design.The chip circuit has the characteristics of high current limiting accuracy,radiation resistance,and programmable.The normal working power supply voltage range of the circuit is2.7V～5.5V,and the current programmable range is 0.1A～1.2A.When the continuous load current is 1.2A,the on-resistance value of the circuit is only 70mΩ.The high reliability of the current-limiting circuit has been proved by tape-out.At the same time,the accuracy of current detection can be as high as 10%,and the response time of the circuit can reach 2μs once the circuit is short-circuited. |
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