CN102522884B

CN102522884B - LDO (Low Dropout Regulator) circuit for high-input voltage

Info

Publication number: CN102522884B
Application number: CN201110426277.7A
Authority: CN
Inventors: 陈泽坚
Original assignee: Atech Automotive Wuhu Co Ltd
Current assignee: Wuhu Etec Automotive Electronics Co.,Ltd.
Priority date: 2011-12-19
Filing date: 2011-12-19
Publication date: 2015-04-01
Anticipated expiration: 2031-12-19
Also published as: CN102522884A

Abstract

The invention discloses a LDO circuit for high-input voltage. A voltage dropping resistor is arranged between a voltage output V-IN end and a voltage output V-OUT end, wherein the voltage output V-OUT end is connected with a power supply input end; a collector electrode of PNP (Plug-and-Play) triode Q1 is connected with the voltage output V-OUT end; an emitter electrode of the PNP triode Q1 is connected with the voltage output V-IN end; a base electrode of the PNP triode Q1 is connected with a collector electrode of an NPN triode Q2; an emitter electrode of the triode Q2 is accessed to the voltage output V-IN end by a diode D1 and a divider resistance R1; a base electrode of the triode Q2 is connected between the triode D1 and the divider resistance R1; the base electrode of the triode Q2 is accessed to a collector electrode of a switching tube Q3 by a voltage regulator tube; the collector electrode of the switching tube Q3 is further connected with the emitter electrode of the triode Q2 by a divider resistance R2, an emitter electrode of the switching tube Q3 is grounded, and a base electrode of the switching tube Q3 is connected with a control pin of the switching tube Q3. The LDO circuit is not only suitable for low-voltage environment, but also can be used under high voltage; moreover, compared with a DC (Direct Current)-DC reduction voltage circuit, the LDO circuit has low cost, reduces the work amount for debugging workpiece, and achieves small-current no-loss work when the switching tube is under the off state.

Description

A kind of LDO circuit that can be used for high input voltage

Technical field

The present invention relates to one all adaptable LDO circuit in high voltage and low voltage environment.

Background technology

Reduction voltage circuit conventional at present mainly contains LDO (LDO is low dropout regulator, means low pressure difference linear voltage regulator) and DC-DC (DC/DC transducer is the electric pressure converter effectively exporting fixed voltage after changing input voltage) two types.DC-DC has the advantages such as delivery efficiency is high, energy is large, makes it in the reduction voltage circuit of high voltage input, have performance advantage, but the DC-DC reduction voltage circuit problems such as to there is circuit hardware cost high, and the complicated and EMC of debugging is poor; And LDO reduction voltage circuit, circuit hardware cost is low, debugs convenient high with EMC, but can not be used for high voltage environment, makes the use of these two kinds of reduction voltage circuits receive restriction.

Summary of the invention

Technical problem to be solved by this invention be realize one can in high input voltage circuit LDO circuit.

To achieve these goals, the technical solution used in the present invention is: a kind of LDO circuit that can be used for high input voltage, its voltage export V-IN end and voltage export V-OUT hold between be provided with dropping resistor, and voltage exports V-OUT end connection power input, the collector electrode of PNP triode Q1 connects voltage and exports V-OUT end, its emitter connects voltage and exports V-IN end, its base stage connects the collector electrode of NPN triode Q2, the accessing voltage through diode D1 and divider resistance R1 and export V-IN and hold of described triode Q2 emitter, its base stage is connected between diode D1 and divider resistance R1, and base stage is through voltage-stabiliser tube access switching tube Q3 collector electrode, described switching tube Q3 collector electrode is also connected with triode Q2 emitter by divider resistance R2, its grounded emitter, base stage meets switching tube Q3 and controls pin.

Described dropping resistor is made up of parallel resistance more than two.

Described dropping resistor Zhong Mei road parallel circuits is equipped with switch.

The invention has the advantages that LDO circuit of the present invention can not only be adapted to low voltage environment and can also use under high voltages, and it is with low cost to compare DC-DC reduction voltage circuit, reduce hardware debug workload, under switching tube closed condition, realize the work of small area analysis idle simultaneously.

Accompanying drawing explanation

Mark in the content expressed every width accompanying drawing in specification of the present invention below and figure is briefly described:

Fig. 1 is LDO circuit structure diagram;

Mark in above-mentioned figure is: 1, dropping resistor.

Embodiment

Known see Fig. 1, this circuit voltage export V-IN end and voltage export V-OUT hold between set up dropping resistor 1, dropping resistor 1 is made up of the resistance of two-way more parallel, a control switch and the resistance of each parallel circuits circuit is all connected, thus the parallel resistance quantity of place in circuit can be controlled, and reasonably configure resistance by circuit parameter, thus the demand of Different L DO circuit can be met, such as, can be arranged in parallel the resistance of 6 2K2 Ω.Wherein voltage exports V-OUT end connection power input, the electric current of this power end is via input after voltage stabilizing circuit U1 process, circuit has a PNP triode Q1 like this, a NPN triode Q2 and NPN triode Q3, triode Q3 is as switching tube, wherein the collector electrode of triode Q1 connects voltage and exports V-OUT end, its emitter connects voltage and exports V-IN end, wherein base stage connects the collector electrode of N triode Q2, the accessing voltage through diode D1 and divider resistance R1 and export V-IN and hold of the emitter of triode Q2, its base stage is connected between diode D1 and divider resistance R1, and base stage is through voltage-stabiliser tube access switching tube Q3 collector electrode, the collector electrode of switching tube Q3 is also connected with triode Q2 emitter by divider resistance R2, its grounded emitter, base stage meets switching tube Q3 and controls pin.Wherein resistance R1, R2, R3 can be all the voltage-stabiliser tube of the diode of the resistance of 5K6 Ω, the optional model BAS21 of diode D1, the optional model BZX84-C6V8 of voltage-stabiliser tube.

Its operation principle of foregoing circuit structure is as follows:

When small area analysis works, electric current exports V-IN end by dropping resistor 1 to voltage.During small area analysis, the power of dropping resistor 1 can meet the demands.When simultaneously electric current is less, voltage export V-IN end and voltage exports V-OUT hold between pressure drop less, although voltage output V-OUT terminal voltage value is higher, less electric current makes the power of LDO can meet the demands equally.When voltage output V-OUT terminal voltage value is higher, the dividing potential drop of resistance R2 and resistance R3 is higher equally, the emitting stage voltage of such triode Q2 is higher than the triode Q2 base voltage obtained by voltage-stabiliser tube voltage stabilizing, and triode Q2 closes and do not work, and therefore triode Q1 closes and do not work.If now closing switch pipe Q3, then this shunt regulating circuit does not produce extra power consumption completely.

When big current works, electric current produces larger pressure drop by dropping resistor 1, voltage exports V-OUT terminal voltage value and is dragged down, now the partial pressure value of resistance R2 and resistance R3 will be less than the triode Q2 base voltage obtained by voltage-stabiliser tube voltage stabilizing, triode Q2 is switched on work, and therefore triode Q1 is by the electric current on triode Q2 conducting shunting dropping resistor 1.Because the partial pressure value of resistance R2 and resistance R3 is fixing, as long as electric current increases, when voltage output V-OUT terminal voltage is pulled down to and makes the partial pressure value of resistance R2 and resistance R3 lower than voltage-stabiliser tube, namely triode Q1 can work.Pressure drop on such dropping resistor 1 will be a fixed value, arrange suitable dividing potential drop parameter and dropping resistor 1 is operated in rated operating range.Switch on controlled hypotension resistance 1 increases resistor coupled in parallel number in dropping resistor 1 also can increase the ability of this circuit by electric current.

Above by reference to the accompanying drawings to invention has been exemplary description; obvious specific implementation of the present invention is not subject to the restrictions described above; as long as have employed the improvement of the various unsubstantialities that method of the present invention is conceived and technical scheme is carried out; or design of the present invention and technical scheme directly applied to other occasion, all within protection scope of the present invention without to improve.

Claims

1., for a LDO circuit for high input voltage, it is characterized in that:

The voltage of circuit export V-IN end and voltage export V-OUT hold between be provided with dropping resistor (1), and voltage exports V-OUT end by chip U1 connection power input, the collector electrode of PNP triode Q1 connects voltage and exports V-OUT end, its emitter connects voltage and exports V-IN end, its base stage connects the collector electrode of NPN triode Q2, described triode Q2 emitter accesses voltage through diode D1 and divider resistance R1 and exports V-IN and hold, its base stage is connected between diode D1 and divider resistance R1, and base stage is through voltage-stabiliser tube access switching tube Q3 collector electrode, described switching tube Q3 collector electrode is also connected with triode Q2 emitter by divider resistance R3, described switching tube Q3 grounded emitter, the base stage of described switching tube Q3 meets switching tube Q3 and controls pin, resistance R2 two ends connect the emitter that voltage exports V-OUT end and triode Q2,

Described dropping resistor (1) is made up of parallel resistance more than two;

Described dropping resistor (1) Zhong Mei road parallel circuits is equipped with switch;

Resistance R1, R2, R3 are the resistance of 5.6K Ω,

Described dropping resistor (1) is the resistance of 6 2.2 K Ω in parallel, and described voltage-stabiliser tube model is BZX84-C6V8 type voltage-stabiliser tube;

The method of work of the described LDO circuit for high input voltage is as follows:

When small area analysis works, electric current exports V-IN end by dropping resistor (1) to voltage, during small area analysis, the power of dropping resistor (1) can meet the demands, when electric current is less simultaneously, voltage export V-IN end and voltage exports V-OUT hold between pressure drop less, now voltage output V-OUT terminal voltage value is higher, and less electric current makes the power of LDO meet power demands; When voltage output V-OUT terminal voltage value is higher, the dividing potential drop of resistance R2 and resistance R3 is higher equally, now the emitting stage voltage of triode Q2 is higher than the triode Q2 base voltage obtained by voltage-stabiliser tube voltage stabilizing, triode Q2 closes and does not work, then triode Q1 closes and does not work, if now closing switch pipe Q3, then this LDO circuit being used for high input voltage does not produce extra power consumption completely;

When big current works, electric current produces larger pressure drop by dropping resistor (1), voltage exports V-OUT terminal voltage value and is dragged down, now the partial pressure value of resistance R2 and resistance R3 will be less than the triode Q2 base voltage obtained by voltage-stabiliser tube voltage stabilizing, triode Q2 is switched on work, then triode Q1 is by the electric current in triode Q2 conducting shunting dropping resistor (1); As long as electric current increases, voltage output V-OUT terminal voltage is pulled down to and makes the partial pressure value of resistance R2 and resistance R3 lower than voltage-stabiliser tube, triode Q1 works, then the pressure drop on dropping resistor (1) will be fixed value, arranges dividing potential drop parameter and dropping resistor 1 is operated in rated operating range.