CN208890637U - A kind of start-up circuit of high reliability - Google Patents
A kind of start-up circuit of high reliability Download PDFInfo
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- CN208890637U CN208890637U CN201821580561.3U CN201821580561U CN208890637U CN 208890637 U CN208890637 U CN 208890637U CN 201821580561 U CN201821580561 U CN 201821580561U CN 208890637 U CN208890637 U CN 208890637U
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Abstract
The utility model discloses a kind of start-up circuits of high reliability, including first resistor, second resistance, 3rd resistor, first capacitor, the second capacitor, first diode, an AC signal port, an output port, a ground wire port.High reliability circuit disclosed in the utility model can effectively inhibit the overcurrent and overvoltage stress problem of output port, also effectively inhibiting first diode, reverse recovery current drags down the problem of starting port at work, reduces the risk that product short circuit is abnormal under high temperature.The washability of circuit parameter is also further improved simultaneously, so that start-up circuit debugging is easy, greatly improves the consistency of volume production product.
Description
Technical field
The utility model relates to a kind of start-up circuit, in particular to a kind of starting electricity for improving Switching Power Supply unfailing performance
Road.
Background technique
In Switching Power Supply, general control IC can have following function or pin: power supply foot, current detecting
Foot, Voltage Feedback foot, duty ratio output pin, soft start foot etc..
In normal power up, power supply foot reaches unlatching thresholding from under-voltage protection voltage, and control IC starts to work, soft start
Foot voltage starts to climb.At the same time Voltage Feedback foot due to electric power output voltage it is very low, the optocoupler that feedback is isolated does not have electric current,
The voltage of Voltage Feedback foot can rise as the current potential of soft start foot rises, and duty ratio can be increased with Voltage Feedback foot at this time
And increase.When output voltage reaches setting value, Voltage Feedback foot, duty ratio, output voltage reach balance, keep stable output
Voltage.
In master control IC starting, if output voltage itself has very big residual voltage or even greater than setting voltage value, this
When opto-coupled feedback have biggish sourcing current, Voltage Feedback foot current potential is pulled in one compared with low potential, master control IC is caused to continue one
The section time exports without duty ratio.If reaching certain time, control IC internal logic can determine that circuit enters abnormal protection shape at this time
State and the longer time that stops working, are easy to appear the state of product intermittent work, output voltage just can not at the same time
, there is power down phenomenon in pressure stabilizing output.
Above-mentioned exception be also typically present with during dynamic hop.If during load jump, continuing for some time nothing and accounting for
Empty ratio, accessory power supply are not powered, and control IC is caused to enter under-voltage condition.Hereafter external start-up circuit is started to work, and makes master control IC
Power supply foot reaches unlatching threshold voltage again, IC soft start again.And output voltage causes light commonly greater than output voltage at this time
Coupling electric current is larger, persistently drags down Voltage Feedback foot and has caused machine difficult.
To solve the above-mentioned problems, it will usually the FB foot starting of master control IC as shown in Figure 1 a kind of be added in external circuit
Circuit.When control IC power supply is under-voltage, BOS foot is internally integrated metal-oxide-semiconductor and generates switching signal, gives inductance charge and discharge, passes through two poles
Pipe rectifier boost.Therefore go out to generate square-wave signal in BOS.The square-wave signal accesses start-up circuit first diode anode.Lead to again
Cross first capacitor, the second capacitor make Voltage Feedback pin current potential be lifted so that master control IC starts successfully.
The start-up circuit is resolved above-mentioned abnormal problem, makes power supply product output can under various conditions not
Master control IC can be caused to enter abnormal protection state and cause to export power down.But the circuit has some defects: control IC voltage
Feedback foot will appear overvoltage, current stress and the risk dragged down by the reverse recovery current transient state of first diode.In high temperature
Under, control IC short-circuit protection logical miss is easily caused, the protection resting period is abnormal, high temperature short-circuit failure.
Utility model content
In view of this, the utility model proposes a kind of start-up circuit with high reliability, the technical issues of solution is solution
The certainly risk of high temperature lower switch power supply short circuit failure promotes product and the unfailing performance of master control IC.The utility model makes simultaneously
Each start-up circuit parameter is relatively independent, is easy debugging, greatly reduces the influence of capacitance tolerance bring, is promoted under product batch
Consistency problem.
For the risk for solving above-mentioned reliability, the utility model provides a kind of high reliability start-up circuit of Switching Power Supply,
It include: first resistor, second resistance, first capacitor, the second capacitor, first diode, an AC signal input port, an output
Port, a ground wire port；The AC signal input port is connected to one end and the first capacitor of the first resistor
One end, the other end of first resistor and the other end of first capacitor are connected to the anode of the first diode；Described
One diode cathode is connected to the output port by the second resistance；The output port passes through described the
Two capacitance connections are to the ground wire port.
As another scheme of the utility model, a kind of high reliability start-up circuit, including first resistor, the first electricity
Appearance, the second capacitor, second resistance, first diode, an AC signal input port, an output port, a ground wire port；It is described
AC signal input port be connected to the first diode anode, first diode cathode is connected to first electricity
One end of resistance and one end of first capacitor；The other end of the first resistor and the other end of first capacitor are connected to described
One end of second resistance, the other end of second resistance are connected to the output port；The output port passes through the second electricity
Hold and is connected to the ground wire port.
As the third scheme of the utility model, a kind of high reliability start-up circuit, including first resistor, the first electricity
Appearance, the second capacitor, second resistance, first diode, an AC signal input port, an output port, a ground wire port；It is described
AC signal input port the anode of first diode is connected to by first resistor, second resistance；The first capacitor
It is in parallel with the first resistor；The cathode of the first diode is connected to the output port；The output end
Mouth passes through second capacitance connection to the ground port.
It further include 3rd resistor, the 3rd resistor is connected with first capacitor as the improvement to above 3 kinds of schemes.
The utility model include it is following the utility model has the advantages that due to second resistance exist greatly limit output port voltage and
Current stress improves the unfailing performance of product；First diode reverse recovery current has been eliminated simultaneously to draw to output port
Low risk；Under high temperature, the short circuits of power supply can be greatly promoted, it is therefore prevented that the logic for controlling the defencive function module of IC is mixed
Disorderly.Simultaneously because the addition of second resistance, 3rd resistor, the circuit debugging is extremely convenient, greatly reduces first capacitor, the second electricity
Hold, the type selecting difficulty of first diode.Type selecting and range of tolerable variance are wider, have very big mention to the consistency of product volume production
It rises.
Detailed description of the invention
Fig. 1 is start-up circuit in the prior art；
Fig. 2 is the circuit diagram of the utility model embodiment one；
Fig. 3 is the circuit diagram of the utility model embodiment four；
Fig. 4 is the power supply of 1 circuit of application drawing in short circuit, the voltage stress waveform and current waveform of FB foot；
Fig. 5 is the voltage stress waveform and electric current of FB foot using an embodiment of the present invention in power supply short circuit
Waveform.
Specific embodiment
Embodiment one
Fig. 1 shows the circuit diagram of the utility model.
The utility model embodiment one includes: an AC signal port AC SIGN (BOS foot), an output port FB, a ground
Line end mouth GND, first capacitor C1, the second capacitor C2, first resistor R1, second resistance R2, first diode D1.The end AC SIGN
Mouth is connected to first capacitor C1, and is connected to first diode anode by first capacitor C1；First diode cathode passes through
Second resistance R2 is connected to the output a mouthful FB；Output port FB is connected to the ground line end mouth GND by the second capacitor C2；First resistor
R1 is in parallel with first capacitor.
Embodiment one improves the principle of the short circuits of start-up circuit are as follows: before short circuit, since product works normally, and AC
SIGN is low level, and start-up circuit is not turned on；The voltage of first capacitor C1 is also released by first resistor R1 as 0V.Product short circuit
When, auxiliary power supply is insufficient, and the square-wave signal of the port AC SIGN constantly intermittent can generate, and gives output port FB mono- always
Start voltage.And at this point, output port FB has been high level due to short circuit, the FB when IC that the present embodiment uses is usually short-circuit
For 5.3V.So first capacitor C1 is equivalent to short circuit in first task of start-up circuit, the second capacitor C2 is high level
5.3V, AC SIGN port square wave are got higher by low, and start-up circuit starts to charge.First capacitor C1 both end voltage is 0V at this time, can be seen
For short-circuit condition, moment impact electric current is very big, actual measurement 120mA or so, while also causing the second capacitor C2 voltage instantaneous liter
Height causes output port FB foot to rise to 12V or so from 5.3V.When AC SIGN generates square wave for the first time, output port FB
Transient state overstress, will cause the integrity problem of control IC, while also have the risk for causing IC locked, interfere the normal work of IC
Make.After the overstress problem that square wave generates for the first time, since the transient current for flowing through first diode D1 is larger, the one or two pole
Pipe D1 shutdown can also generate biggish reverse recovery current, and measured current spike can reach -80mA, cause output port FB foot quilt
Transient state is pulled down to 2V or so, as the raising of environment temperature can even be pulled low to 0V.FB foot is pulled low when short-circuit, can cause IC
Internal short-circuit protects timing module timing resetting, and short-circuit protection is not had the hiccups, and endangers power supply.The second resistance R2's of the utility model
Introducing can eliminate the above risk, and second resistance R2 concrete function is the overcurrent and overvoltage for limiting transient state port FB, also significantly
Reduce the reverse recovery current of first diode；The stress of the port FB is set to be limited in 8V tolerance interval below, while the end FB
The phenomenon that mouth is dragged down by the reverse recovery current of first diode has not existed.As shown in figure 5, the high reliability of the utility model
Start-up circuit has very big optimization compared to Fig. 4 to voltage, the current stress waveform of the port output pin FB, in acceptable model
In enclosing.And the phenomenon that port FB is drawn as low potential has not existed.
High temperature short-circuit test is carried out to power supply product, the phenomenon that high temperature short-circuit failure also no longer occurs.To first capacitor C1,
Second capacitor C2 carries out high temperature short-circuit test under conditions of being increased considerably or being reduced, the phenomenon that high temperature short-circuit failure also not
Occur again.Experiments have shown that the high reliability start-up circuit of the utility model can have very device tolerance and short circuits
Big promotion, from the overvoltage of the port FB, overcurrent stress and be reversed that restoring current drags down fundamentally to solve high temperature short
The abnormal problem of road failure.
Usual first capacitor C1, the second capacitor C2 are for pF rank, and capacitor's capacity spacing is larger, and type selecting is difficult.It improves
While short circuits, the utility model due to second resistance R2 metering function, while taking into account reliability, first
The value of capacitor C1 can obtain more greatly, prevent the shunt capacitance C2 of the stress overshoot of port FB from can obtain smaller, so that
The type selecting of device is more easier.Since capacitance tolerance is larger, resistance tolerance generally only has ± 1%, so that the consistency of the circuit
It is relatively good.The influence of stress limitation and reduction reverse recovery current to port FB all keeps very good controllability, to amount
The consistency and reliability of production bring further guarantee.
Embodiment two
The embodiments of the present invention second is that adjust, the AC signal input terminal on the basis of example 1
Mouth is connected to the first diode anode, and first diode cathode is connected to one end and the first electricity of the first resistor
One end of appearance；The other end of the first resistor and the other end of first capacitor are connected to one end of the second resistance,
The other end of second resistance is connected to the output port；The output port passes through the second capacitance connection to the ground
Port.
The working principle of the present embodiment is the same as example 1, and details are not described herein.
Embodiment three
The embodiments of the present invention two are also to adjust on the basis of example 1, and the port AC SIGN passes through the
One capacitor C1 is connected to one end of second resistance；The anode of the other end connection diode D1 of second resistance, the yin of diode D1
Pole is connected to the output a mouthful FB；Output port FB is connected to the ground line end mouth GND by the second capacitor C2；First resistor R1 and first
Capacitor is in parallel.
Example IV
Fig. 2 shows one of circuit diagrams of the utility model embodiment four.
The utility model embodiment on the basis of above 3 embodiments fourth is that increase resistance R3, R3 and capacitor C1 phase
Series connection.R3 can also not affect the implementation of the utility model behind C1 before C1.
The principle and embodiment one of the reliability of the raising start-up circuit of embodiment two are essentially identical.By increasing 3rd resistor
R3, electric current when starting together with second resistance R2 to first time carry out metering function, greatly reduce the wind of the port FB overstress
Danger and FB foot are reversed the risk that restoring current transient state drags down.Improve the reliability of product.It is different in second resistance R2
It is only the metering function for playing AC SIGN and starting moment for the first time, and 3rd resistor R3 not only plays AC SIGN first
Metering function when secondary starting, and also assist in the effect of releasing of first resistor R1.The controllability of resistance so is enhanced, it is right
It is more convenient in the type selecting of resistance and debugging.
The high reliability start-up circuit of the utility model, core idea are in first capacitor C1 and the second capacitor C2
Alternating current path on current-limiting resistance is added, reduce output port stress and the logic risk being pulled low, improve the reliable of product
Property；Current-limiting resistance R2, first capacitor C1, first diode D1 belong to series relationship, the series system of any different order,
In the protection scope of the utility model；From anywhere in the alternating current path of first capacitor C1 and the second capacitor C2, one is sealed in
A or multiple current-limiting resistances, belong to the core idea of the utility model, also in the protection scope of the utility model.
Claims (4)
1. a kind of start-up circuit of high reliability, it is characterised in that: including first resistor, first capacitor, the second capacitor, the second electricity
Resistance, first diode, an AC signal input port, an output port, a ground wire port；The AC signal input port
It is connected to one end of the first resistor and one end of first capacitor, the other end of first resistor and the other end of first capacitor
It is connected to the anode of the first diode；The first diode cathode is connected to one end of the second resistance,
The other end of the second resistance is connected to the output port；The output port is connected by second capacitor
It is connected to the ground wire port.
2. a kind of start-up circuit of high reliability, it is characterised in that: including first resistor, first capacitor, the second capacitor, the second electricity
Resistance, first diode, an AC signal input port, an output port, a ground wire port；The AC signal input port
It is connected to the first diode anode, the first diode cathode is connected to one end and the of the first resistor
One end of one capacitor；The other end of the first resistor and the other end of first capacitor are connected to the one of the second resistance
End, the other end of second resistance are connected to the output port；The output port passes through second capacitance connection
To the ground wire port.
3. a kind of start-up circuit of high reliability, it is characterised in that: including first resistor, first capacitor, the second capacitor, the second electricity
Resistance, first diode, an AC signal input port, an output port, a ground wire port；The AC signal input port
The anode of first diode is connected to by the first resistor, the second resistance；The first capacitor with it is described
First resistor it is in parallel；The cathode of the first diode is connected to the output port；The output port passes through
Second capacitance connection is to the ground wire port.
4. according to claim 1 to the start-up circuit of high reliability described in 3 any one, it is characterised in that: further include third
Resistance, the 3rd resistor are connected with first capacitor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821580561.3U CN208890637U (en) | 2018-09-27 | 2018-09-27 | A kind of start-up circuit of high reliability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821580561.3U CN208890637U (en) | 2018-09-27 | 2018-09-27 | A kind of start-up circuit of high reliability |
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| Publication Number | Publication Date |
|---|---|
| CN208890637U true CN208890637U (en) | 2019-05-21 |
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ID=66514190
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| Application Number | Title | Priority Date | Filing Date |
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| CN201821580561.3U Active CN208890637U (en) | 2018-09-27 | 2018-09-27 | A kind of start-up circuit of high reliability |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109120141A (en) * | 2018-09-27 | 2019-01-01 | 广州金升阳科技有限公司 | A kind of start-up circuit of high reliability |
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2018
- 2018-09-27 CN CN201821580561.3U patent/CN208890637U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109120141A (en) * | 2018-09-27 | 2019-01-01 | 广州金升阳科技有限公司 | A kind of start-up circuit of high reliability |
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