A kind of protection circuit suitable for switch power source output voltage
Technical field
The utility model relates to protective circuit of switch power source technical fields, especially a kind of to be suitable for Switching Power Supply output electricity
The protection circuit of pressure.
Background technique
For Switching Power Supply, quick power supply output is to measure one of the index of high performance switch power supply.But it is fast
The power supply output of speed often brings other problems, such as:
Voltage overshoot is larger, remote overburden voltage range, damage load;
Power supply moment output energy is excessive, causes busbar voltage to reduce, causes false alarm;
Quick electromagnetic energy conversion, interference system signal influence Switching Power Supply normal work.
For this purpose, in the case where the power supply output rise time is shorter, it is also contemplated that above-mentioned protection question.
Under normal conditions, loop response speed can be changed, be slowly increased specified rate to solve in program, but all existed
Deficiency, change loop response speed can slow down voltage rising time, but in testing transient variation, the time can also become therewith
Slowly, standard is not reached requirement.Voltage rising time can quantitatively be slowed down by being slowly increased in program, but its time is often excessive,
Reach several hundred milliseconds, the remote super normal output time.
Utility model content
The purpose of the utility model is to provide a kind of protection circuits suitable for switch power source output voltage, it is intended to slow down electricity
Source output voltage solves the problems, such as that electric power output voltage is too fast and brings, while evading and slowing down electric power output voltage in the prior art
Measure bring other problems.
To reach above-mentioned technical purpose, the utility model provides a kind of protection electricity suitable for switch power source output voltage
Road, the protection circuit include:
Turn-on control circuit and given voltage control circuit;
The input of the turn-on control circuit terminates start-up and shut-down control signal ON/OFF, output termination given voltage control electricity
Road, the given voltage control circuit input termination voltage Setting signal Uset, and output termination voltage gives output signal U s.
Preferably, the turn-on control circuit includes:
Divider resistance R7, it unilateral diode D4, pull down resistor R6, switching tube Q2, divider resistance R1, divider resistance R2, opens
Close pipe Q1;
Start-up and shut-down control signal ON/OFF is met on the left of divider resistance R7, reversed unilateral diode D4, diode are taken over control in right side
The upper end of another termination pull down resistor R6 of D4 and the grid of switching tube Q2, the lower end pull down resistor R6 ground connection, switching tube Q2's
Source electrode ground connection, drain electrode connect the lower end of divider resistance R2, the upper end of divider resistance R2 grid with divider resistance R1, switching tube Q1 respectively
The other end of pole connection, divider resistance R1 connects positive 15V voltage, and the source electrode of switching tube Q1 connects positive 15V voltage, the leakage of switching tube Q1
Pole connects given voltage control circuit.
Preferably, the given voltage control circuit includes:
Current-limiting resistance R3, pull down resistor R4, unilateral diode D1, unilateral diode D2, feedback capacity C1, current-limiting resistance
R5, operational amplifier U1, unilateral diode D3;
The upper end of pull down resistor R4 and the left end of current-limiting resistance R3 connect the drain electrode of switch Q1, the other end of pull down resistor R4
- 15V voltage is connect, the inverting input terminal of another termination operational amplifier U1 of current-limiting resistance R3, operational amplifier U1's is same mutually defeated
Enter end ground connection;The both ends of the feedback capacity C1 are separately connected the inverting input terminal and output end of operational amplifier U1;Unidirectional two
The anode of pole pipe D1 connects the inverting input terminal of operational amplifier U1, and cathode connects the anode and unilateral diode D3 of unilateral diode D2
Cathode, the cathode of unilateral diode D2 connects the output end of operational amplifier U1, and it is given that the anode of unilateral diode D3 connects voltage
The right end of output signal U s and current-limiting resistance R5, current-limiting resistance R5 are voltage Setting signal Uset.
The effect provided in utility model content is only the effect of embodiment, rather than whole effects that utility model is all
Fruit, a technical solution in above-mentioned technical proposal have the following advantages that or the utility model has the advantages that
Compared with prior art, the utility model by design it is a kind of make the slow protection circuit risen of electric power output voltage,
When power supply stops exporting, start-up and shut-down control signal is high level, and switching tube Q1, Q2 are on state, operational amplifier U1 output
End is low level, and by the clamper of unilateral diode D1, D2, D3, voltage gives output signal U s and is pulled low;When power initiation is defeated
When out, start-up and shut-down control signal is low level, and switching tube Q1, Q2 are not on-state, and operational amplifier U1 output end is high level,
Under the integral action of feedback capacity C1, the voltage gives output signal U s and is clamped slow rising, is finally reached setting value.
The utility model solves slows down power supply output measure bring other problems in the prior art, and power supply output not only may be implemented
Voltage do not have overshoot or overshoot very little, power rail voltage only great fluctuation process, supply voltage output voltage gradient it is relatively slow, to signal
Lesser effect is interfered, feedback capacity size can also be adjusted according to actual needs, realizes that voltage output slope is adjustable, and not
Influence transient response index.
Detailed description of the invention
Fig. 1 is a kind of protection circuit suitable for switch power source output voltage provided in the utility model embodiment
Figure.
Specific embodiment
In order to clearly illustrate the technical characterstic of this programme, below by specific embodiment, and its attached drawing is combined, to this
Utility model is described in detail.Following disclosure provides many different embodiments or example is used to realize the utility model
Different structure.In order to simplify the disclosure of the utility model, hereinafter the component of specific examples and setting are described.This
Outside, the utility model can in different examples repeat reference numerals and/or letter.This repetition is in order to simplified and clear
Purpose itself does not indicate the relationship between discussed various embodiments and/or setting.It should be noted that illustrated in the accompanying drawings
Component be not drawn necessarily to scale.The utility model be omitted the description to known assemblies and treatment technology and process to avoid
It is unnecessarily limiting the utility model.
With reference to the accompanying drawing to a kind of guarantor suitable for switch power source output voltage provided by the utility model embodiment
Protection circuit is described in detail.
As shown in Figure 1, the utility model embodiment discloses a kind of protection circuit suitable for switch power source output voltage,
The protection circuit includes:
Divider resistance R7, it unilateral diode D4, pull down resistor R6, switching tube Q2, divider resistance R1, divider resistance R2, opens
Close pipe Q1, current-limiting resistance R3, pull down resistor R4, unilateral diode D1, unilateral diode D2, unilateral diode D3, feedback capacity
C1, current-limiting resistance R5, operational amplifier U1.
The divider resistance R7, unilateral diode D4, pull down resistor R6, switching tube Q2, divider resistance R1, divider resistance
R2, switching tube Q1 form turn-on control circuit;
It is the current-limiting resistance R3, pull down resistor R4, unilateral diode D1, unilateral diode D2, unilateral diode D3, anti-
Feed holds C1, current-limiting resistance R5, operational amplifier U1 and forms given voltage control circuit.
Start-up and shut-down control signal ON/OFF is met on the left of divider resistance R7, reversed unilateral diode D4, diode are taken over control in right side
The upper end of another termination pull down resistor R6 of D4 and the grid of switching tube Q2, the lower end pull down resistor R6 ground connection, switching tube Q2's
Source electrode ground connection, drain electrode connect the lower end of divider resistance R2, the upper end of divider resistance R2 grid with divider resistance R1, switching tube Q1 respectively
The other end of pole connection, divider resistance R1 connects positive 15V voltage, and the source electrode of switching tube Q1 connects positive 15V voltage, the leakage of switching tube Q1
Pole connects the upper end of pull down resistor R4 and the left end of current-limiting resistance R3, another termination -15V voltage of pull down resistor R4, current-limiting resistance
The inverting input terminal of another termination operational amplifier U1 of R3, the non-inverting input terminal ground connection of operational amplifier U1;The feedback electricity
The both ends for holding C1 are separately connected the inverting input terminal and output end of operational amplifier U1;The anode of unilateral diode D1 connects operation and puts
The inverting input terminal of big device U1, cathode meet the anode of unilateral diode D2 and the cathode of unilateral diode D3, unilateral diode D2
Cathode connect the output end of operational amplifier U1, the anode of unilateral diode D3 connects voltage and gives output signal U s and current-limiting resistance
The right end of R5, current-limiting resistance R5 are voltage Setting signal Uset.
When power supply stops exporting, start-up and shut-down control signal ON/OFF is that high level makes the grid of switching tube Q2 after partial pressure
Extremely high level, Q2 conducting, the at this time drain electrode of Q2 lead switching tube Q1 by the partial pressure of divider resistance R1 and R2 for low level
Logical, the drain electrode of Q1 is high level.The left end of current-limiting resistance R3 is high level, makes the output end low level of operational amplifier U1,
Due to the effect of feedback capacity C1, the inverting input terminal voltage of operational amplifier U1 is 0, adds unilateral diode D1, D2, D3
Clamper, make the conduction voltage drop of the anode voltage diode D1 of diode D2, about 0.7V or so, the output of operational amplifier U1
The D1 being negative adds the conduction voltage drop of D2, about 1.4V or so.Voltage gives output signal U s and is pulled down to 0V at this time.
When power initiation output, start-up and shut-down control signal ON/OFF is low level, and switching tube Q2 grid is low level, cannot
Conducting, then Q1 grid is+15V, can not be connected.The left end of current-limiting resistance R3 is negative value, and the output end of operational amplifier U1 becomes
For high level, due to the effect of unilateral diode D1 and D2, the output end and inverting input terminal of operational amplifier U1 cannot pass through
Unilateral diode D1 is connected with D2, can only be attached by feedback capacity C1, at this time under the action of feedback capacity C1, is formed
Integrating circuit, what when output end voltage of operational amplifier U1 gradually rose, during raised, the voltage being clamped is given
Output signal U s will be also gradually increased.Stopped during being output to starting output to realize by power supply, the given output of voltage
The control that signal Us gradually rises, the actual output voltage of final power supply can also gradually rise.
It is defeated that power supply not only may be implemented by designing a kind of protection circuit for making the slow liter of electric power output voltage in the utility model
Out voltage do not have overshoot or overshoot very little, power rail voltage only great fluctuation process, supply voltage output voltage gradient it is relatively slow, to letter
Number lesser effect of interference, can also adjust feedback capacity size according to actual needs, realize that voltage output slope is adjustable, and
Transient response index is not influenced.
The above is only the preferred embodiment of the utility model only, is not intended to limit the utility model, all at this
Made any modifications, equivalent replacements, and improvements etc., should be included in the utility model within the spirit and principle of utility model
Protection scope within.