DCDC current-limiting circuit
Technical Field
The present invention relates to a dc power circuit, and more particularly, to a DCDC current limiting circuit.
Background
In the current consumer market, the demand for portable electronic devices, particularly battery-powered electronic products, such as mobile phones and tablet computers, is increasing, and how to reduce power consumption and improve efficiency and prolong the working life of the battery to the maximum extent becomes an urgent issue to be solved in the design of power management such as a DCDC converter. The application of the current limiting circuit can prevent the switch device in the power supply conversion chip from bearing excessive current impact to cause unnecessary damage and protect the power supply chip; meanwhile, the working efficiency of the chip is improved.
However, the DCDC current limiting circuit in the power converter of fig. 1 is mainly used in the current prior art, such as the basic principle of the DCDC current limiting circuit in fig. 1: in order to detect the current of the switching tube, a current detection resistor R10 is connected in series between the MOS tube Q10 and the ground. The actual current is known from the voltage drop across the current sensing resistor R10, which converts the current to a voltage that is compared to the set reference voltage value V. And performing logical AND operation on the output of the comparator COMP and the input PWM signal and outputting a result, and adjusting the frequency and the duty ratio of a driving signal of the MOS tube Q10 according to the output result to achieve the purpose of current limiting. The selection of the reference voltage also has certain requirements, and the selection of the reference voltage is too small, generally about 1V, so that the power consumption of the current detection resistor R10 is relatively large.
Disclosure of Invention
The invention provides a DCDC current-limiting circuit which realizes the reduction of power consumption while protecting a chip.
The embodiment of the invention provides a DCDC current-limiting circuit, which comprises a first current-limiting circuit, a second current-limiting circuit and a first current-limiting circuit, wherein the first current-limiting circuit comprises a first current-limiting circuit and a second current-limiting circuit; the power supply conversion module, the mirror current module and the enabling control module; the power conversion module is used for converting input direct-current voltage into required direct-current voltage, and is electrically connected with the mirror current module; the mirror current module receives the output current of the power supply conversion module, one path of the current flows through a current limiting resistor to flow to an emitting electrode of a first triode, the other path of the current flows through a first resistor to flow to an emitting electrode of a second triode, mirror current flows out of a collector electrode of the second triode, a base electrode of the first triode is electrically connected with a base electrode of the second triode, and a second resistor is connected between the base electrode of the first triode and the ground in series; the enabling control module is connected between the mirror current module and the power conversion module in series, receives the mirror current, and controls the conduction and the cut-off of a third triode in the enabling control module through the mirror current so as to adjust the output current in the power conversion module.
Further, the first triode and the second triode are two PNP triodes with the same parameters.
Further, the third triode is an NPN triode.
Further, the power conversion module includes: the DCDC power conversion chip comprises an enabling pin and an output voltage monitoring pin, wherein the enabling pin is connected with a collector electrode of a third triode in the enabling control module, the level of the potential on the enabling pin is adjusted by controlling the on-off of the third triode, and the power conversion module outputs different currents through the high potential and the low potential; the output voltage monitoring pin is connected with the feedback circuit and used for outputting stable required direct current voltage.
Further, the model of the DCDC power conversion chip is TPS54232 DR.
Further, the feedback circuit comprises a first capacitor, a third resistor and a fourth resistor; the third resistor and the fourth resistor are connected in series, the first capacitor is connected with the third resistor in parallel, and an electric connection end between the third resistor and the fourth resistor is electrically connected with the output voltage monitoring pin.
Further, the enable control module further comprises a second capacitor, a fifth resistor and a sixth resistor; and a fifth resistor is connected in series between the collector of the second triode and the base of the third triode, a sixth resistor is connected in series between the collector of the second triode and the ground, and the collector and the emitter of the third triode are respectively connected with two ends of the second capacitor.
According to the technical scheme provided by the invention, a mirror current module and an enabling control module are connected in series in a power conversion module circuit, the mirror current module receives output current of the power conversion module, one path of the current flows through a current-limiting resistor to flow to an emitter of a first triode, the other path of the current flows through a first resistor to flow to an emitter of a second triode, mirror current flows out of a collector of the second triode, a base of the first triode is electrically connected with a base of the second triode, and a second resistor is connected in series between the base of the first triode and the ground; the enabling control module is connected between the mirror current module and the power conversion module in series, receives the mirror current, and controls the conduction and the cut-off of a third triode in the enabling control module through the mirror current so as to adjust the output current in the power conversion module. The problem that the power consumption of current limiting on a resistor in a traditional circuit is large is solved, and the effect of reducing the power consumption while protecting a chip is achieved.
Drawings
FIG. 1 is a circuit diagram of a prior art DCDC current limiting circuit;
fig. 2 is a schematic structural diagram of a DCDC current-limiting circuit according to an embodiment of the present invention;
FIG. 3 is a circuit diagram of a mirror current module according to an embodiment of the present invention;
fig. 4 is a circuit diagram of a DCDC current limiting circuit according to a second embodiment of the present invention;
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Example one
Fig. 2 is a schematic structural diagram of a DCDC current-limiting circuit according to a first embodiment of the present invention, fig. 3 is a circuit diagram of a mirror current module according to a first embodiment of the present invention, and as shown in fig. 2 and 3, the DCDC current-limiting circuit includes: a power conversion module 110, a mirror current module 120, and an enable control module 130; the power conversion module 110 is configured to convert an input dc voltage into a required dc voltage, and the power conversion module 110 is electrically connected to the mirror current module 120; the mirror current module 120 receives the output current of the power conversion module 110, one path of the current flows through a current limiting resistor R to an emitter of a first triode Q1, the other path of the current flows through a first resistor R1 to an emitter of a second triode Q2 to flow out mirror current from a collector of the second triode Q2, a base of the first triode Q1 is electrically connected with a base of a second triode Q2, and a second resistor R2 is connected between the base of the first triode Q1 and the ground in series; the enable control module 130 is connected in series between the mirror current module 120 and the power conversion module 110, and the enable control module 130 receives the mirror current, and controls the third transistor in the enable control module 130 to be turned on and off through the mirror current to adjust the output current in the power conversion module 110.
The first triode Q1 and the second triode Q2 are two PNP triodes with the same parameters.
Specifically, the two identical triodes ensure that the base-to-emitter voltages are the same, and the bases of the two triodes are equipotential points, so that the voltage on the current-limiting resistor R is the same as the voltage on the first resistor R1. That is, the current flowing through the current limiting resistor R and the first resistor R1 is inversely proportional to the resistance, for example, the current limiting resistor R is 0.1 Ω, and the first resistor R is 1K Ω, and if the current flowing through the current limiting resistor R is I1A, the current flowing through the first resistor R1 is I1 0.1mA, and the current flowing through the first resistor R is 0.1mA due to the presence of the current limiting resistor R and is 1/1000 of the total current in the loop, thereby playing a role of limiting the current. When the same 1A current flows through the current limiting resistor of the conventional current limiting circuit and the current limiting resistor R of the present embodiment, the power consumption of the current limiting resistor on the conventional current limiting circuit is about 1W, whereas the power consumption on the current limiting resistor R of the present invention is only 0.1W. The effect of low power consumption is achieved.
According to the DCDC current-limiting circuit provided by the embodiment of the invention, a mirror current module and an enabling control module are connected in series in a power supply conversion module circuit, the mirror current module receives output current of the power supply conversion module, one path of the current flows through a current-limiting resistor to flow to an emitter of a first triode, the other path of the current flows through a first resistor to flow to an emitter of a second triode, mirror current flows out of a collector of the second triode from the emitter of the second triode, a base of the first triode is electrically connected with a base of the second triode, and a second resistor is connected in series between the base of the first triode and the ground; the enabling control module is connected between the mirror current module and the power conversion module in series, receives the mirror current, and controls the conduction and the cut-off of a third triode in the enabling control module through the mirror current so as to adjust the output current in the power conversion module. The problem that the power consumption of current limiting on a resistor in a traditional circuit is large is solved, and the effect of reducing the power consumption while protecting a chip is achieved.
Example two
Fig. 4 is a circuit diagram of a DCDC current-limiting circuit according to a second embodiment of the present invention. As shown in fig. 4, the present embodiment is based on the above-described embodiment.
The power conversion module 110 includes a DCDC power conversion chip and a peripheral circuit of the DCDC chip, the DCDC power conversion chip includes an enable pin EN and an output voltage monitoring pin VSENSE, the enable pin EN is connected with a collector of a third triode Q3 in the enable control module, the level of an EN potential on the enable pin is adjusted by controlling the on and off of the third triode Q3, and the power conversion module 110 outputs different currents through the high and low potentials; the output voltage monitoring pin VSENSE is connected to a feedback circuit for outputting a stable desired dc voltage.
Specifically, the DCDC power conversion chip is a TPS system chip, such as TPS54232, TPS54232D, TPS54232DR, and the like, and is preferably a TPS54232DR chip.
The TPS54232DR chip comprises an input pin VIN, a start pin BOOT, a phase terminal pin PH, a grounding pin GND, a compensation pin COMP, an output voltage monitoring pin VSENSE, an enable pin EN and a soft start pin SS; the pin VIN is connected with an external direct-current voltage, the VIN pin is connected with a resistor R7 and a resistor R8 in series and used for voltage division, and a start pin BOOT and a phase end pin PH are respectively and electrically connected with two ends of a capacitor C3 and used for improving the voltage of a power supply; a phase terminal pin PH is connected in series with a first terminal of an inductor L, and a second terminal of the inductor L is electrically connected with an input terminal of the mirror current module 120; a freewheeling diode D is connected between the phase end pin PH and the grounding pin GND to prevent current mutation in current, a capacitor C4 is connected in series between the second end of the inductor L and the grounding pin GND, and a capacitor C5 is connected in parallel at two ends of the capacitor C4; a capacitor C6 and a resistor R9 are sequentially connected in series between a pin COMP of the compensation pin and the ground, and a capacitor C7 is connected in parallel at two ends of the capacitor C6 and the resistor R9; the enable pin EN is connected to the third transistor Q3 in the enable control module 130, the level of the electric potential on the enable pin is adjusted by controlling the on and off of the third transistor Q3, and the power conversion module 110 outputs different currents through the high and low electric potentials; the output voltage monitoring pin VSENSE is connected to a feedback circuit for outputting a stable desired dc voltage.
Wherein the feedback circuit comprises a first capacitor C1, a third resistor R3 and a fourth resistor R4; the third resistor R3 and the fourth resistor R4 are connected in series, the first capacitor C1 and the third resistor R3 are connected in parallel, and the required output direct-current voltage is stabilized by adjusting the resistance values of the third resistor R3 and the fourth resistor R4.
The enabling control module further comprises a second capacitor C2, a fifth resistor R5 and a sixth resistor R6; a fifth resistor R5 is connected in series between the collector of the second triode Q2 and the base of the third triode Q3, a sixth resistor R6 is connected in series between the collector of the second triode Q2 and the ground, and the collector and the emitter of the third triode Q3 are respectively connected with two ends of a second capacitor C2.
Further, the third triode is a switch type transistor, preferably an NPN triode.
The specific working principle of the above embodiment of the invention is as follows: an input pin VIN of the power conversion module 110 receives an external direct-current voltage, a DCDC power conversion chip outputs a current through an inductor L, the mirror current module 120 receives the current, one of the currents flows through a current limiting resistor R to flow to a first triode Q1, the other current flows through a first resistor R1 to flow to a second triode Q2, and forms a mirror current, as the output current gradually increases, the current flowing through the current limiting resistor R also gradually increases, the same current flowing through the first resistor R1 also increases, the mirror current also gradually increases, the mirror current flows through the enable control module 130, drives a third tube Q3 of the enable control module 130, when the current flowing through the third triode Q3 exceeds a turn-on value, the third triode Q3 is turned on, so that the potential of an enable pin EN in the power conversion module 110 is pulled down, the power conversion module 110 receives a low potential, the current is adjusted to reduce the output current, the same mirror current is reduced, the current flowing through the third triode Q3 is gradually reduced, when the current is smaller than the opening value of the third triode Q3, the third triode Q3 is cut off, the potential on the enable pin EN becomes high, the power supply conversion module is connected with high potential, the current is adjusted, and the output current becomes high. The current is adjusted repeatedly to achieve the purpose of current limiting.
According to the DCDC current-limiting circuit provided by the embodiment of the invention, a mirror current module and an enabling control module are connected in series in a power supply conversion module circuit, the mirror current module receives output current of the power supply conversion module, one path of the current flows through a current-limiting resistor to flow to an emitter of a first triode, the other path of the current flows through a first resistor to flow to an emitter of a second triode, mirror current flows out of a collector of the second triode from the emitter of the second triode, a base of the first triode is electrically connected with a base of the second triode, and a second resistor is connected in series between the base of the first triode and the ground; the enabling control module is connected between the mirror current module and the power conversion module in series, receives the mirror current, and controls the conduction and the cut-off of a third triode in the enabling control module through the mirror current so as to adjust the output current in the power conversion module. The problem that the power consumption of current limiting on a resistor in a traditional circuit is large is solved, and the effect of reducing the power consumption while protecting a chip is achieved.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.