Utility model content
The purpose of this utility model is to provide a kind of USB charge protector and USB charger, and be intended to the USB charger solving prior art, after the output overcurrent of USB interface, USB interface exists locked problem.
First aspect, the utility model provides a kind of USB charge protector, comprises ON-OFF control circuit, and described USB charge protector also comprises reference voltage provides circuit, current sampling circuit and data comparison circuit, wherein, reference voltage provides one end of the output of circuit and current sampling circuit to be electrically connected with two inputs of data comparison circuit respectively, the output of data comparison circuit is electrically connected with the input of ON-OFF control circuit, the output termination USB output interface of ON-OFF control circuit, when the voltage ratio reference voltage that data comparison circuit compares the one end drawing current sampling circuit provides the output end voltage of circuit low, the output control switch control circuit of data comparison circuit is opened, when the voltage ratio reference voltage that data comparison circuit compares the one end drawing current sampling circuit provides the output end voltage height of circuit, the output control switch control circuit of data comparison circuit cuts out.
Further, described reference voltage provides circuit to comprise reference voltage source, and the output of reference voltage source is electrically connected with data comparison circuit input.
Further, the first divider resistance that described reference voltage provides circuit to comprise reference voltage source and series connection and the second divider resistance, first divider resistance of series connection and the second divider resistance are connected in parallel on the two ends of reference voltage source, described reference voltage source is three end adjustable shunt reference sources, an input of the connection termination data comparison circuit of the first divider resistance and the second divider resistance.
Further, described current sampling circuit comprises the first sampling resistor and second sampling resistor of series connection, the other end ground connection of the second sampling resistor, another input of another termination data comparison circuit of the first sampling resistor.
Further, described data comparison circuit is comparator, and the output of comparator is electrically connected with the input of ON-OFF control circuit, and the negative pole of comparator connects one end of current sampling circuit, and the positive pole of comparator connects the output that reference voltage provides circuit.
Further, described ON-OFF control circuit comprises N-channel MOS pipe, and grid connects the output of data comparison circuit, and drain electrode connects USB output interface, and source electrode is by current sampling circuit ground connection.
Further, described ON-OFF control circuit also comprises the 5th resistance, and the grid of N-channel MOS pipe connects the output of data comparison circuit by the 5th resistance.
Further, described USB charge protector also comprises the 6th resistance of the negative pole connecing comparator, another termination USB output interface of the 6th resistance.
Second aspect, the utility model provides a kind of USB charger, and described USB charger comprises above-mentioned USB charge protector.
In the utility model, because USB charge protector comprises ON-OFF control circuit, reference voltage provides circuit, current sampling circuit and data comparison circuit, the output termination USB output interface of ON-OFF control circuit, when the voltage ratio reference voltage that data comparison circuit compares the one end drawing current sampling circuit provides the output end voltage of circuit low, the output control switch control circuit of data comparison circuit is opened, when the voltage ratio reference voltage that data comparison circuit compares the one end drawing current sampling circuit provides the output end voltage height of circuit, the output control switch control circuit of data comparison circuit cuts out.Therefore after the output control switch control circuit of data comparison circuit cuts out, when the electric current through current sampling circuit is reduced to normal range (NR) by overcurrent limits, voltage ratio reference voltage due to one end of current sampling circuit provides the output end voltage of circuit to be low, therefore the output of data comparison circuit again control switch control circuit open, thus recover the output of USB output interface, thus solve after the output overcurrent of USB output interface, there is locked problem in USB output interface.
Embodiment
In order to make the purpose of this utility model, technical scheme and beneficial effect clearly understand, below in conjunction with drawings and Examples, the utility model is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the utility model, and be not used in restriction the utility model.
In order to technical scheme described in the utility model is described, be described below by specific embodiment.
Refer to Fig. 1, the USB charge protector that the utility model embodiment provides comprises reference voltage provides circuit 11, current sampling circuit 12, data comparison circuit 13 and ON-OFF control circuit 14.Wherein, reference voltage provides one end of the output of circuit 11 and current sampling circuit 12 to be electrically connected with two inputs of data comparison circuit 13 respectively, the output of data comparison circuit 13 is electrically connected with the input of ON-OFF control circuit 14, the output termination USB output interface of ON-OFF control circuit 14, when the voltage ratio reference voltage that data comparison circuit 13 compares the one end drawing current sampling circuit 12 provides the output end voltage of circuit 11 low, the output control switch control circuit 14 of data comparison circuit 13 is opened, when the voltage ratio reference voltage that data comparison circuit 13 compares the one end drawing current sampling circuit 12 provides the output end voltage height of circuit 11, the output control switch control circuit 14 of data comparison circuit 13 cuts out.
The operation principle of the USB charge protector that the utility model embodiment provides is as follows:
Power supply exports 5V by transformer pressure-reducing, the voltage of the output end voltage of data comparison circuit 13 benchmark circuit for providing voltage 11 and one end of current sampling circuit 12, under normal circumstances, electric current through current sampling circuit 12 is less than 2.4A, so the voltage ratio reference voltage of one end of current sampling circuit 12 provides the output end voltage of circuit 11 to be low, so the output of data comparison circuit 13 exports a high level always, ON-OFF control circuit 14 is opened, and now USB output interface exports 5V voltage; When the electric current of current sampling circuit 12 is within 2.5-3.3A scope, the voltage ratio reference voltage of one end of current sampling circuit 12 provides the output end voltage of circuit 11 to be high, so the output of data comparison circuit 13 exports a low level, ON-OFF control circuit 14 is closed, and now USB output interface does not export; When the electric current through current sampling circuit 12 is reduced to 2.0-2.4A by overcurrent limits, the voltage ratio reference voltage of one end of current sampling circuit 12 provides the output end voltage of circuit 11 to be low, so the output of data comparison circuit 13 exports a high level, ON-OFF control circuit 14 is opened, thus recover the output of USB output interface, thus solve after the output overcurrent of USB output interface, there is locked problem in USB output interface.
Referring to Fig. 2, is the circuit theory diagrams of the USB charge protector that the utility model embodiment provides.
Reference voltage provides circuit 11 to comprise reference voltage source, and the output of reference voltage source is electrically connected with an input of data comparison circuit 13.In the utility model embodiment, reference voltage source specifically can adopt three end adjustable shunt reference sources; The first divider resistance R1 that reference voltage provides circuit 11 can also comprise series connection and the second divider resistance R2, first divider resistance R1 of series connection and the second divider resistance R2 is connected in parallel on the two ends of reference voltage source, and the output voltage of reference voltage source just can be optionally configured to from Vref (2.5V) to any value within the scope of 36V by the first divider resistance R1 and the second divider resistance R2.An input of the connection termination data comparison circuit 13 of the first divider resistance R1 and the second divider resistance R2.
Current sampling circuit 12 comprises the first sampling resistor R3 and the second sampling resistor R4 of series connection, the other end ground connection of the second sampling resistor R4, another input of another termination data comparison circuit 13 of the first sampling resistor R3.
Data comparison circuit 13 can be comparator, and the output of comparator is electrically connected with the input of ON-OFF control circuit 14, and the negative pole of comparator connects one end of current sampling circuit 12, and the positive pole of comparator connects the output that reference voltage provides circuit 11.The comparator that the utility model embodiment adopts can be LM358, its have two independently, high-gain, internal frequency compensate dual operational amplifier, most low energy sampling 3MV, the resistance of 10 milliohms so just can be used to sample, then resistance loss 0.024V when load 2.4A, therefore can improve delivery efficiency.
ON-OFF control circuit 14 comprises N-channel MOS pipe, and grid G connects the output of data comparison circuit 13, and drain D connects USB output interface, and source S passes through current sampling circuit 12 ground connection, particular by the second sampling resistor R4 ground connection of current sampling circuit 12.ON-OFF control circuit 14 can also comprise the 5th resistance R5, and the grid G of N-channel MOS pipe connects the output of data comparison circuit 13 by the 5th resistance R5.
The USB charge protector that the utility model embodiment provides can also comprise the 6th resistance R6 of the negative pole connecing comparator, another termination USB output interface of the 6th resistance R6.After having served as the closedown of current control N-channel MOS pipe, at this time by the negative pole of the 6th resistance R6 to comparator, maintain the high level state of comparator negative pole, N-channel MOS pipe is thoroughly closed, there will not be N-channel MOS pipe half conducting state, and cause burning metal-oxide-semiconductor phenomenon, or also has the Problems existing of electric current after closing.
The USB charge protector that the utility model embodiment provides can also comprise the first electric capacity C1, the first electric capacity C1 mono-termination first divider resistance R1 and the link of the second divider resistance R2 and the positive pole of comparator, the output of another termination reference voltage source.
The USB charge protector that the utility model embodiment provides can also comprise the second electric capacity C2, and the negative pole of comparator is by the second electric capacity C2 ground connection.
The USB charge protector that the utility model embodiment provides can also comprise the seven resistance R7 source-series with reference voltage, can also comprise the 3rd electric capacity C3 with the reference voltage source of connecting and the 7th resistance R7 parallel connection.
The circuit working principle of the USB charge protector that the utility model embodiment provides is as follows:
Power supply exports 5V by transformer pressure-reducing, comparator compares positive pole and the cathode voltage of comparator, under normal circumstances, electric current through the first sampling resistor R3 and the second sampling resistor R4 is less than 2.4A, so the cathode voltage of comparator is lower than cathode voltage, so comparator output terminal exports a high level always, make the conducting of N-channel MOS pipe, now USB output interface exports 5V voltage; When the electric current through the first sampling resistor R3 and the second sampling resistor R4 is within 2.5-3.3A scope, the cathode voltage of comparator is higher than cathode voltage, so comparator output terminal exports a low level, N-channel MOS pipe is closed, and now USB output interface does not export; When the electric current through the first sampling resistor R3 and the second sampling resistor R4 is reduced to 2.0-2.4A by overcurrent limits, the cathode voltage of comparator is lower than cathode voltage, so comparator output terminal exports a high level, make the conducting of N-channel MOS pipe, thus recover the output of USB output interface, thus solve after the output overcurrent of USB output interface, there is locked problem in USB output interface.
The utility model embodiment still provides a kind of USB charger comprising the USB charge protector that the utility model embodiment provides.
The foregoing is only preferred embodiment of the present utility model; not in order to limit the utility model; all do within spirit of the present utility model and principle any amendment, equivalent to replace and improvement etc., all should be included within protection range of the present utility model.