CN105955379A - High-voltage starting circuit with turning off function - Google Patents

Abstract

The invention belongs to the technical field of electronics and particularly relates to a high-voltage starting circuit with a turning off function. The linear voltage stabilizing circuit which can be used for high-voltage starting and is provided with the turning off function is achieved by additionally adding a limited number of transistors, and the problems that a chip is excessively large in standby power consumption and a power tube is short in service life are solved. The high-voltage starting circuit comprises a main circuit, a bias and reference circuit and a control logic circuit. The bias and reference circuit is quite low in power consumption, capable of being produced by directly inputting voltage and capable of working independently to provide bias and reference for the logic circuit and the main circuit. The control logic circuit is used for detecting the states of an input point and an output point. The main circuit receives the bias and reference from the bias and reference circuit and a control signal of the logic circuit to finally produce stable output voltage or turn off the power tube.

Description

A kind of high-voltage starting circuit turned off

Technical field

The invention belongs to electronic technology field, be specifically related to a kind of high-voltage starting circuit turned off.

Background technology

In the present age, the situation needing power supply to supply is ubiquitous, and in industry and the communications field, input is typically the highest electricity Pressure, if now needing power supply, the most often using provides a stable voltage to high-voltage starting circuit, even because Isolation type switching power supply changer is originally also required to power supply in start-up course, so high-voltage starting circuit is most important.High pressure opens Galvanic electricity road the most court has less power consumption, the input voltage of wider range, and the direction of higher power density is developed.

The most common scheme is to use depletion type MOS FET as adjusting pipe to control output voltage.As it is shown in figure 1, exhaust Type MOSFET adjusts pipe scheme and has control circuit simply, can be with the advantage of self-starting.But due to depletion type NMOSFET Threshold value be negative, if simply the grid end of depletion type NMOSFET being pulled to earth potential, cannot ensure by it turn off. Only in the case of source is higher than grid end certain voltage, could effectively close depletion type NMOSFET.Due to NMOSFET The output point of start-up circuit need to compensate, i.e. sizable electric current need to be provided output limit to be pushed on this road of NMOSFET Far, if main body power tube can not be closed in the case of having peripheral power supply, then the power consumption of chip will become very big, needs More many one-tenth is spent originally to carry out heat dissipation design.Turn on for a long time, also can affect the life-span of power tube.

Summary of the invention

The invention aims to solve the problems referred to above, it is proposed that use the scheme of enhancement mode NMOSFET, and devise phase The breaking circuit answered is to ensure that enhancement mode MOSFET can be closed at any time, thus reduces power consumption, and can extend NMOSFET Life-span.

The technical scheme is that a kind of high-voltage starting circuit turned off, including biasing and reference circuit, control logic electricity Road and main body circuit；The input termination external high pressure power supply of described biasing and reference circuit, the outfan of biasing and reference circuit divides Do not connect the input of control logic circuit and the input of main body circuit；The output termination main body circuit of described control logic circuit Input, the power supply termination external high pressure power supply of main body circuit；Wherein, biasing and reference circuit for control logic circuit and Main body circuit provides bias voltage and reference voltage；Control logic circuit is used for detecting the voltage of input point, and according to the knot of detection Structure produces control signal and is sent to main body circuit, controls main body circuit and produces stable output voltage；

Described main body circuit include the first PMOS MP1, the second PMOS MP2, the 3rd PMOS MP3, the 4th PMOS MP4, the first npn type bipolar transistor Q1, the second npn type bipolar transistor Q2, the first resistance R1, Two resistance R2, the first JFET transistor JFET1, the first enhancement mode mosfet transistor LDMOS1 and the first computing are put Big device A1；

The drain electrode of the first enhancement mode mosfet transistor LDMOS1 connects external high pressure power supply, and its grid connects the first PMOS The drain electrode of MP1, the source electrode of the first enhancement mode mosfet transistor LDMOS1 passes sequentially through the first resistance R1 and second electricity Ground connection after resistance R2；

The drain electrode of the first JFET transistor JFET1 connects external high pressure power supply, its grounded-grid；

The source electrode of the first PMOS MP1 connects the source electrode of the first JFET transistor JFET1, the grid of the first PMOS MP1 Pole connects biasing and the bias voltage of reference circuit output；

The source electrode of the 3rd PMOS MP3 connects the drain electrode of the first PMOS MP1, and the grid of the 3rd PMOS MP3 connects The outfan of operational amplifier A 1, the drain electrode of the 3rd PMOS MP3 passes sequentially through the first resistance R1 and the second resistance R2 Rear ground connection；

The source electrode of the second PMOS MP2 connects the source electrode of the first JFET transistor JFET1, the grid of the second PMOS MP2 Pole connects biasing and the bias voltage of reference circuit output；

The source electrode of the 4th PMOS MP4 connects the source electrode of the first JFET transistor JFET1, the grid of the 4th PMOS MP4 Pole connects outside enable signal；

The colelctor electrode of the first npn type bipolar transistor Q1 connects the drain electrode of the first PMOS MP1, and the first bipolar npn is brilliant The base stage of body pipe Q1 connects the junction point of the second PMOS MP2 drain electrode and the 4th PMOS MP4 drain electrode, the first NPN type The emitter stage of bipolar transistor Q1 passes sequentially through ground connection after the first resistance R1 and the second resistance R2；

The colelctor electrode of the second npn type bipolar transistor Q2 connects the second PMOS MP2 drain electrode and the 4th PMOS MP4 The junction point of drain electrode, the base stage of the second npn type bipolar transistor Q2 interconnects with colelctor electrode, the second npn type bipolar transistor The emitter stage of Q2 passes sequentially through ground connection after the first resistance R1 and the second resistance R2；

The positive input of the first operational amplifier A 1 connects biasing and the reference voltage of reference circuit output, the first operational amplifier The negative input of A1 is by ground connection after the second resistance R2, and the enable termination of the first operational amplifier A 1 is outside enables signal.

Beneficial effects of the present invention, for comparing traditional circuit, only adds additional the transistor of Limited Number, is achieved that a kind of use Make the turned off linear voltage-stabilizing circuit of high voltage startup, solve the problem that chip stand-by power consumption is excessive and the power tube life-span is too short.

Accompanying drawing explanation

Fig. 1 conventional depletion mode MOSFET adjusts pipe scheme schematic diagram；

The concrete structure schematic diagram of Fig. 2 new type control circuit；

The main body circuit structural representation of Fig. 3 present invention.

Detailed description of the invention

Below in conjunction with the accompanying drawings, technical scheme is described in detail:

The present invention is overall as in figure 2 it is shown, include main body circuit, biasing and reference circuit and the control logic circuit that band turns off, its Being characterized by possessing band turn-off function, enhancement mode NMOSFET in main body circuit can be closed at any time.Due to biasing and Reference circuit power consumption is the least, and the present invention is used and it directly produced by input voltage, and the scheme worked alone, biasing and base Quasi-circuit is the circuit providing biasing and benchmark to logic circuit and main body circuit, keeps work at any time.Described control is patrolled Volume circuit, for detecting under-voltage, the overvoltage of input point or whether the voltage of output point reaches externally fed standard, supplies if outside The voltage given is more than detected value, controls logic and will detect and close whole high-voltage starting circuit.And main body circuit is in normal work Time, accept to come automatic biasing and the biasing of reference circuit and benchmark, by electric resistance partial pressure and the negative feedback of operational amplifier, finally produce Raw stable output voltage.When off state, by closedown power tube in the hope of saving power consumption to greatest extent and increasing the service life.

Concrete main body circuit as it is shown on figure 3, normal mode of operation when, BIAS (biasing) voltage is normal, MP1 pipe with MP2 manages equal normal bias.Being high due to EN again, so amplifier output is normal, MP4 pipe does not works, and therefore, passes through computing The negative feedback that amplifier A1, enhancement mode mosfet transistor LDMOS1, resistance R1, resistance R2, MP3 pipe are formed is adjusted Saving output voltage, making output voltage is a stability number.Owing to using the adjustment pipe of N-type, so limit is internally positioned, Secondary limit is externally-located, and owing to it is frequently necessary to plug-in big electric capacity to the transient response making output point have at output point, so Output stage must bias the biggest electric current, pushes secondary limit to high frequency, therefore will consume the biggest electric current.

When output voltage is higher than certain detected value, controls logic and will detect that and close whole high-voltage starting circuit, close mode For by BIAS voltage high, thus close MP1 pipe, MP2 pipe, simultaneously EN is dragged down, by operational amplifier A 1 Draw high thus have turned off MP3 pipe.Owing to EN is low level, MP4 pipe is opened, and has one electric current and flows through MP4, crystalline substance Body pipe Q1 and transistor Q2, owing to MP1 pipe, MP3 manage now all in off state, so by transistor Q1, Together with the grid of LDMOS1 is successfully received with source electrode, thus successfully close power tube.By design EN current potential and The breadth length ratio of MP4, can be easy to by cut-off current arrange the lowest, it is achieved thereby that reduce power consumption target.

In view of the foregoing it is apparent that, by using enhancement mode NMOSFET, circuit successfully solves the problem of standby shutoff, Achieve a kind of turned off linear voltage-stabilizing circuit as high voltage startup, thus save power consumption, continue the power tube life-span.

Those of ordinary skill in the art is it will be appreciated that embodiment described here is to aid in the former of the reader understanding present invention Reason, it should be understood that protection scope of the present invention is not limited to such special statement and embodiment.The ordinary skill of this area Personnel can according to these technology disclosed by the invention enlightenment make various other various concrete deformation without departing from essence of the present invention and Combination, these deformation and combination are the most within the scope of the present invention.

Claims (1)

1. the high-voltage starting circuit that can turn off, including biasing and reference circuit, control logic circuit and main body circuit；Described The input termination external high pressure power supply of biasing and reference circuit, the outfan of biasing and reference circuit connects control logic circuit respectively Input and the input of main body circuit；The input of the output termination main body circuit of described control logic circuit, main body circuit Power supply termination external high pressure power supply；Wherein, biasing and reference circuit are for providing biased electrical to control logic circuit and main body circuit Pressure and reference voltage；Control logic circuit is for detecting the voltage of input point, and produces control signal transmission according to the structure of detection To main body circuit, control main body circuit and produce stable output voltage；

Described main body circuit include the first PMOS MP1, the second PMOS MP2, the 3rd PMOS MP3, the 4th PMOS MP4, the first npn type bipolar transistor Q1, the second npn type bipolar transistor Q2, the first resistance R1, Two resistance R2, the first JFET transistor JFET1, the first enhancement mode mosfet transistor LDMOS1 and the first computing are put Big device A1；

The drain electrode of the first enhancement mode mosfet transistor LDMOS1 connects external high pressure power supply, and its grid connects the first PMOS The drain electrode of MP1, the source electrode of the first enhancement mode mosfet transistor LDMOS1 passes sequentially through the first resistance R1 and second electricity Ground connection after resistance R2；

The drain electrode of the first JFET transistor JFET1 connects external high pressure power supply, its grounded-grid；

The source electrode of the first PMOS MP1 connects the source electrode of the first JFET transistor JFET1, the grid of the first PMOS MP1 Pole connects biasing and the bias voltage of reference circuit output；

The source electrode of the 3rd PMOS MP3 connects the drain electrode of the first PMOS MP1, and the grid of the 3rd PMOS MP3 connects The outfan of operational amplifier A 1, the drain electrode of the 3rd PMOS MP3 passes sequentially through the first resistance R1 and the second resistance R2 Rear ground connection；

The source electrode of the second PMOS MP2 connects the source electrode of the first JFET transistor JFET1, the grid of the second PMOS MP2 Pole connects biasing and the bias voltage of reference circuit output；

The source electrode of the 4th PMOS MP4 connects the source electrode of the first JFET transistor JFET1, the grid of the 4th PMOS MP4 Pole connects outside enable signal；

The colelctor electrode of the first npn type bipolar transistor Q1 connects the drain electrode of the first PMOS MP1, and the first bipolar npn is brilliant The base stage of body pipe Q1 connects the junction point of the second PMOS MP2 drain electrode and the 4th PMOS MP4 drain electrode, the first NPN type The emitter stage of bipolar transistor Q1 passes sequentially through ground connection after the first resistance R1 and the second resistance R2；

The colelctor electrode of the second npn type bipolar transistor Q2 connects the second PMOS MP2 drain electrode and the 4th PMOS MP4 The junction point of drain electrode, the base stage of the second npn type bipolar transistor Q2 interconnects with colelctor electrode, the second npn type bipolar transistor The emitter stage of Q2 passes sequentially through ground connection after the first resistance R1 and the second resistance R2；

The positive input of the first operational amplifier A 1 connects biasing and the reference voltage of reference circuit output, the first operational amplifier The negative input of A1 is by ground connection after the second resistance R2, and the enable termination of the first operational amplifier A 1 is outside enables signal.