CN104779583B - The design method of switch power supply die mould output short circuit protection circuit - Google Patents
The design method of switch power supply die mould output short circuit protection circuit Download PDFInfo
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- CN104779583B CN104779583B CN201510216909.5A CN201510216909A CN104779583B CN 104779583 B CN104779583 B CN 104779583B CN 201510216909 A CN201510216909 A CN 201510216909A CN 104779583 B CN104779583 B CN 104779583B
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Abstract
The invention discloses a kind of switch power supply die mould output short circuit protection circuit, including comparator U1, switching diode D2 and nonpolar electric capacity C2, and resistance R1, resistance R2, resistance R3, resistance R4 and resistance R5；Switching diode D2 anode and resistance R1 one end connect and are the input V IN of output short circuit protection circuit; switching diode D2 negative electrode connects with nonpolar electric capacity C2 one end and resistance R3 one end; the resistance R3 other end connects with comparator U1 inverting input; the in-phase input end of resistance R1 and resistance R2 connection end and resistance R5 one end with comparator U1 connects, and comparator U1 output end is the output end V OUT of output short circuit protection circuit；The invention also discloses a kind of design method of switch power supply die mould output short circuit protection circuit.The achievable hiccup formula short-circuit protection of the present invention, it is practical with self-recovering function.
Description
Technical field
The present invention relates to switch power technology field, more particularly, to a kind of switch power supply die mould output short circuit protection electricity
The design method on road.
Background technology
With the fast development of electronic technology, protective circuit of switch power source turns into circuit design vital one
Point.At present, power supply or the conventional protection scheme of Switching Power Supply have a lot：(1) it is divided into according to the difference of sampled signal：Current mode is protected
Protection circuit and voltage-type protection circuit.Current mode protection circuit is largely used in general protection circuit, the type needs electric current
Sampling resistor, can flow through very big electric current on resistance, according to small resistance current sampling resistor, then need at signal
Reason, amplification, such that circuit is complicated, increase cost.It can also be entered using current sensor or Hall sensor etc.
Row current sampling, but because current sensor price is higher, and many current sensors need to power up the normal work of ability in addition
Make, this causes circuit structure complicated again, cost increase.And voltage-type protection circuit, without sample rate current, sampled voltage is only needed,
Partial pressure is carried out by big valued resistor and achieves that simple in construction, small power consumption, cost is low.(2) according to the control to output current
It is divided into：Current-limiting type protection circuit, the type that dams or the flow pattern protection circuit that subtracts, thorough turn-off type protection circuit and it can thoroughly turn off switch
The self-recovery protection circuit of pipe.1. current-limiting type protection circuit is that output voltage declines when power output end overload or short circuit
And by output current limitation within the specific limits.The advantage of the protected mode is：Protection domain is big, strong antijamming capability, its electricity
Road is typically relatively simple, and power supply easily recovers after failture evacuation.Have the disadvantage：Protect speed slow, during output short circuit protection, still have compared with
Big electric current flows through, and power consumption is big.2. the type that dams subtracts flow pattern protection circuit：In switch converters output overloading or short circuit, protect
Protection circuit is acted immediately, and output current and voltage can be made to reduce rapidly.The advantage of the protection circuit is：Protection act speed is fast,
Effect is good, power attenuation is small, it is adaptable to the larger power supply of power output.Have the disadvantage：The protection circuit is more complicated, circuit debugging
Cumbersome, power supply is difficult self- recoverage after failture evacuation.3. thorough turn-off type protection circuit, i.e., once after protection circuit action,
Even if excessively stream or short trouble are eliminated, power supply still has been at off state, it is necessary to be first turned off power supply, restart system could be extensive
Return to work work, circuit can not realize self- recoverage, it is impossible to meet the requirement of intrinsic safety electric source.4. can thorough on-off switching tube self- recoverage type
Protection circuit, this kind of protection circuit usually requires current detection circuit, short circuit or overloads the composition such as decision circuitry, delay circuit,
Circuit is complex；And it is general can recovery-type protection circuit after main circuit failure, although output voltage can be limited
Electric current is very big in than relatively low scope, but now for system, because Switching Power Supply is in fact also in work.Therefore, for applied to
The intrinsic safe explosion-proof power supply of hazardous environment, the spark energy that short trouble is produced is considerable, it is more likely that ignite inflammable, explosive gas
Body and its mixture, it is difficult to realize that intrinsic safety is exported.
Current China's coal-mine is large number of, and gas explosion accident is of common occurrence, and the life security to the people causes great
Threaten.Therefore, a kind of voltage-type output short circuit protection circuit suitable for risk environment is designed significant.
The content of the invention
In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is that providing a kind of circuit structure
Simply, with low cost, simple operation, can be achieved hiccup formula short-circuit protection, with self-recovering function, it is practical, be easy to promote
The switch power supply die mould output short circuit protection circuit used.
In order to solve the above technical problems, the technical solution adopted by the present invention is：A kind of switch power supply die mould output short-circuit
Protection circuit, it is characterised in that：Including comparator U1, switching diode D2 and nonpolar electric capacity C2, and resistance R1, resistance
R2, resistance R3, resistance R4 and resistance R5；The anode of the switching diode D2 and resistance R1 one end connect and are the switch
The input V-IN of supply voltage type output short circuit protection circuit, the switch power supply die mould output short circuit protection circuit it is defeated
Enter to hold V-IN to connect with the cathode voltage output end of Switching Power Supply, the negative electrode of the switching diode D2 is with nonpolar electric capacity C2's
One end and resistance R3 one end connect, and the other end of the resistance R1 is grounded by resistance R2, and the nonpolar electric capacity C2's is another
One end is grounded, and the other end of the resistance R3 connects with comparator U1 inverting input, and is grounded by resistance R4, the electricity
The in-phase input end of resistance R1 and resistance R2 connection end and resistance R5 one end with comparator U1 connects, the comparator U1
Power end and the resistance R5 other end connect with the output end VCC of power supply, the earth terminal ground connection of the comparator U1,
The output end of the comparator U1 for the switch power supply die mould output short circuit protection circuit output end V-OUT, it is described to open
The output end V-OUT of powered-down source voltage-type output short circuit protection circuit connects with the input of PWM controlling and driving circuits.
Above-mentioned switch power supply die mould output short circuit protection circuit, it is characterised in that：The comparator U1 is by chip
LM393 is constituted, and the output end of the comparator U1 is connected by resistance R6 with the output end VCC of power supply.
Above-mentioned switch power supply die mould output short circuit protection circuit, it is characterised in that：The Switching Power Supply includes BUCK
Converter circuit, the BUCK converter circuits include PMOS switch pipe VT1, inductance L1, switching diode D1 and polar capacitor
C1, the grid of the PMOS switch pipe VT1 connects with the output end of PWM controlling and driving circuits, the PMOS switch pipe VT1's
Drain as the voltage input end Vi of Switching Power Supply, the source electrode of the PMOS switch pipe VT1 and switching diode D1 negative electrode and electricity
Sense L1 one end connects, and the other end of the inductance L1 connects with polar capacitor C1 positive pole and is the cathode voltage of Switching Power Supply
Output end vo+, the anode of the switching diode D1 and polar capacitor C1 negative pole connect and are the cathode voltage of Switching Power Supply
Output end vo-, cathode voltage output end vo-ground connection of the Switching Power Supply, the cathode voltage output end vo of the Switching Power Supply+
With cathode voltage output end vo-between be connected to load RL.
Present invention also offers a kind of switch power supply die mould that method and step is simple, realization is convenient, practical output
The design method of short-circuit protection circuit, it is characterised in that this method comprises the following steps：
Step 1: the nonpolar electric capacity C2 and resistance R1, resistance R2, resistance R3, resistance R4 and electricity of selection suitable parameters
R5 is hindered, its detailed process is as follows：
Step 101, according to formulaChoose resistance
The resistance of R1 resistance, resistance R2 resistance and resistance R5, wherein, V+1For circuit powered on moment comparator U1 in-phase input end
Magnitude of voltage, V+2For the magnitude of voltage of comparator U1 in-phase input end after circuit working stability, VCC is the output electricity of power supply
Pressure, VoFor the output voltage of Switching Power Supply；
Step 102, according to formulaResistance R3 resistance and resistance R4 resistance are chosen, wherein,
V-2For the magnitude of voltage of comparator U1 inverting input after circuit working stability；
Step 103, first, according to formulaCalculating obtains Switching Power Supply due to output
The magnitude of voltage V of comparator U1 in-phase input end when short circuit is again started up after being stopped+3, then, according to formulaAnd according to nonpolar electric capacity C2 discharge time t=twWhenIt is derived by formulaFinally, according to formulaChoose nonpolar electric capacity C2 capacitance；Wherein,
V-3(t)The magnitude of voltage of comparator U1 inverting input when for nonpolar electric capacity C2 discharge time being t；For nonpolar electricity
The discharge time for holding C2 is twWhen, comparator U1's is anti-phase defeated when Switching Power Supply is again started up after being stopped due to output short-circuit
Enter the magnitude of voltage at end；twFor holding time for switch power supply die mould output short circuit protection circuit, UC2(t)For nonpolar electric capacity C2
Discharge time be t when nonpolar electric capacity C2 on magnitude of voltage,Discharge time for nonpolar electric capacity C2 is twWhen non-pole
Property electric capacity C2 on magnitude of voltage, τ is nonpolar electric capacity C2 discharge time constant, and e is natural constant and takes e=2.71828；
Step 2: connection comparator U1, switching diode D2 and nonpolar electric capacity C2, and resistance R1, resistance R2, resistance
R3, resistance R4 and resistance R5；Its detailed process is as follows：
Step 201, the cathode voltage that one end of switching diode D2 anode and resistance R1 is all connected to Switching Power Supply
Output end；
Step 202, connecting valve diode D2 negative electrode, nonpolar electric capacity C2 one end and resistance R3 one end；
Step 203, the resistance R1 other end is connected with resistance R2 one end and resistance R5 one end and is followed by comparator
U1 in-phase input end；
Step 203, the resistance R3 other end is connected to the inverting input for being followed by comparator U1 with resistance R4 one end；
Step 204, another output end VCC for terminating to power supply by comparator U1 power end and resistance R5；
Step 205, the earth terminal ground connection by the resistance R2 other end, the nonpolar electric capacity C2 other end and comparator U1.
The present invention has advantages below compared with prior art：
1st, the present invention uses voltage-type short-circuit protection circuit, without current detecting, and circuit structure is simple, and power consumption is extremely low, if
Meter is reasonable, and it is convenient to realize, with low cost.
2nd, the present invention uses hiccup formula output short circuit protection, and circuit is operated in hiccup state, by detectable voltage signals come
Judge whether output short-circuit, once detecting output short-circuit, short-circuit protection circuit is acted immediately, thoroughly the switch of cut-out input
Power supply；After short-circuit signal disappears, Switching Power Supply recovers normal work；The circuit can reduce the average electricity of output during lasting excessively stream
Stream, reduces circuit power consumption, and with complete automatic recovery ability, periodically thoroughly shut-off can be achieved, is highly suitable for this
In matter safety circuit.
3rd, the present invention can not be mutated and RC circuit discharging characteristics using diode unilateral conduction and capacitance voltage, to realize
The generation of hiccup formula output short circuit protection signal, samples to output voltage in electric resistance partial pressure form, will pass through diode pair
Electric capacity resulting voltage charge, as the benchmark of hiccup formula output short circuit protection, is that the output of hiccup formula can be achieved without additional benchmark
Short-circuit protection so that circuit structure is simpler, while having saved cost.
4th, the characteristic that the present invention can not be mutated using electric capacity both end voltage, by setting suitable RC circuit parameters, comes true
Determine the time needed for protection signal is maintained, realize that hiccup formula is protected, simple operation.
5th, the present invention can occur overloading or during short trouble in circuit, thoroughly the energy source of cut-out input, by short circuit
Caused spark energy is limited in extremely low scope, available in various switch converters and related electronic products, is especially existed
In the hazardous environments such as colliery, petrochemical industry, the incidence of accident can be effectively reduced, protection property, personal safety are practical, are easy to
Promote the use of.
In summary, circuit structure of the present invention is simple, with low cost, simple operation, and hiccup formula short-circuit protection, tool can be achieved
There is self-recovering function, it is practical, it is easy to promote the use of.
Below by drawings and examples, technical scheme is described in further detail.
Brief description of the drawings
Fig. 1 is the circuit theory diagrams of switch power supply die mould output short circuit protection circuit of the present invention.
Description of reference numerals:
1-switch power supply die mould output short circuit protection circuit；
2-BUCK converter circuits；3-PWM controlling and driving circuits.
Embodiment
As shown in figure 1, the switch power supply die mould output short circuit protection circuit of the present invention, including comparator U1, switch two
Pole pipe D2 and nonpolar electric capacity C2, and resistance R1, resistance R2, resistance R3, resistance R4 and resistance R5；The switching diode D2
Anode and resistance R1 one end connect and for the switch power supply die mould output short circuit protection circuit 1 input V-IN,
The input V-IN of the switch power supply die mould output short circuit protection circuit 1 and the cathode voltage output end phase of Switching Power Supply
Connect, the negative electrode of the switching diode D2 connects with nonpolar electric capacity C2 one end and resistance R3 one end, the resistance R1's
The other end is grounded by resistance R2, the other end ground connection of the nonpolar electric capacity C2, the other end and comparator of the resistance R3
U1 inverting input connects, and is grounded by resistance R4, the connection end of the resistance R1 and resistance R2 and the one of resistance R5
The in-phase input end with comparator U1 is held to connect, the power end of the comparator U1 and the resistance R5 other end are electric with power supply
The output end VCC in source connects, the earth terminal ground connection of the comparator U1, and the output end of the comparator U1 is the Switching Power Supply
The output end V-OUT of voltage-type output short circuit protection circuit 1, the switch power supply die mould output short circuit protection circuit 1 it is defeated
Go out to hold V-OUT and the input of PWM controlling and driving circuits 3 to connect.
In the present embodiment, the comparator U1 is made up of chip LM393, and the output end of the comparator U1 passes through resistance R6
Connect with the output end VCC of power supply.Resistance R6 is the pull-up resistor of comparator U1 output end, when it is implemented, described
Resistance R6 value is 10k Ω.
As shown in figure 1, in the present embodiment, the Switching Power Supply includes BUCK converter circuits 2, the BUCK converters electricity
Road 2 includes PMOS switch pipe VT1, inductance L1, switching diode D1 and polar capacitor C1, the grid of the PMOS switch pipe VT1
Connect with the output end of PWM controlling and driving circuits 3, the drain electrode of the PMOS switch pipe VT1 is the control source of Switching Power Supply
Vi is held, the source electrode of the PMOS switch pipe VT1 connects with switching diode D1 negative electrode and inductance L1 one end, the inductance L1
The other end connect with polar capacitor C1 positive pole and for Switching Power Supply cathode voltage output end vo+, the switching diode
D1 anode and polar capacitor C1 negative pole connect and for Switching Power Supply cathode voltage output end vo-, the Switching Power Supply
Cathode voltage output end vo-ground connection, the cathode voltage output end vo+and cathode voltage output end vo of the Switching Power Supply-between
It is connected to load RL.The conducting and shut-off of the control PMOS switch pipe of PWM controlling and driving circuits 3 VT1.
The design method of the switch power supply die mould output short circuit protection circuit of the present invention, comprises the following steps：
Step 1: the nonpolar electric capacity C2 and resistance R1, resistance R2, resistance R3, resistance R4 and electricity of selection suitable parameters
R5 is hindered, its detailed process is as follows：
Step 101, according to formulaChoose resistance
The resistance of R1 resistance, resistance R2 resistance and resistance R5, wherein, V+1For the same of circuit powered on moment comparator U1
The magnitude of voltage of phase input, V+2For the magnitude of voltage of comparator U1 in-phase input end after circuit working stability, VCC is
The output voltage of power supply, VoFor the output voltage of Switching Power Supply；When it is implemented, V+1、V+2, VCC and VoIt is
The amount of knowing；In the present embodiment, it is known that VCC is 12V, V+1For 2V, V+2For 6V, VoFor 12V；According to formulaThe resistance for choosing resistance R1 is 7.5k Ω, resistance R2's
Resistance is 5k Ω, and resistance R5 resistance is 15k Ω；
Step 102, according to formulaResistance R3 resistance and resistance R4 resistance are chosen, wherein, V-2
For the magnitude of voltage of comparator U1 inverting input after circuit working stability；When it is implemented, V-2For known quantity, due to flowing through out
Diode D2 electric current very little is closed, switching diode D2 forward conduction voltage drop is very low, generally than output voltage VoIt is much smaller, because
ThisCalculation formula in do not consider switching diode D2 forward conduction voltage drop；In the present embodiment,
Know V-2For 3V, resistance R4 resistance is first chosen for 6.8k Ω according to formula 1k Ω≤R4≤10k Ω, further according to formulaCalculate and obtain resistance R3 resistance for 20.4k Ω, when it is implemented, the convenience in order to buy resistance R3,
Using the method rounded up, the resistance for choosing resistance R3 is 20k Ω.Due to nonpolar electric capacity C2 discharge time constant τ=
(R3+R4) C2 is relevant with resistance R3 resistance and resistance R4 resistance, and resistance R3 resistance and resistance R4 resistance are bigger, described
Holding time for switch power supply die mould output short circuit protection circuit 1 is longer, therefore, is meeting formula 1k Ω≤R4≤10k Ω
On the premise of, the larger resistance R4 of selection resistance；
Step 103, first, according to formulaCalculating obtains Switching Power Supply due to output
The magnitude of voltage V of comparator U1 in-phase input end when short circuit is again started up after being stopped+3, then, according to formulaAnd according to nonpolar electric capacity C2 discharge time t=twWhenIt is derived by formulaFinally, according to formulaChoose nonpolar electric capacity C2 capacitance；Wherein,
V-3(t)The magnitude of voltage of comparator U1 inverting input when for nonpolar electric capacity C2 discharge time being t；For nonpolar electricity
The discharge time for holding C2 is twWhen, comparator U1's is anti-phase defeated when Switching Power Supply is again started up after being stopped due to output short-circuit
Enter the magnitude of voltage at end；twFor holding time for switch power supply die mould output short circuit protection circuit 1, UC2(t)For nonpolar electric capacity C2
Discharge time be t when nonpolar electric capacity C2 on magnitude of voltage,Discharge time for nonpolar electric capacity C2 is twWhen non-pole
Property electric capacity C2 on magnitude of voltage, τ is nonpolar electric capacity C2 discharge time constant, and e is natural constant and takes e=2.71828；Tool
When body is implemented, twFor known quantity；In the present embodiment, it is known that twFor 0.3s, according to formulaChoose non-pole
Property electric capacity C2 capacitance be 10 μ F.It should be noted that according to formulaChoose nonpolar electric capacity
During C2 capacitance, the capacitance for calculating obtained nonpolar electric capacity C2 is 10.0395 μ F, in order to buy nonpolar electric capacity C2 side
Just, using the method rounded up, the capacitance for choosing nonpolar electric capacity C2 is 10 μ F.
Step 2: connection comparator U1, switching diode D2 and nonpolar electric capacity C2, and resistance R1, resistance R2, resistance
R3, resistance R4 and resistance R5；Its detailed process is as follows：
Step 201, the cathode voltage that one end of switching diode D2 anode and resistance R1 is all connected to Switching Power Supply
Output end；
Step 202, connecting valve diode D2 negative electrode, nonpolar electric capacity C2 one end and resistance R3 one end；
Step 203, the resistance R1 other end is connected with resistance R2 one end and resistance R5 one end and is followed by comparator
U1 in-phase input end；
Step 203, the resistance R3 other end is connected to the inverting input for being followed by comparator U1 with resistance R4 one end；
Step 204, another output end VCC for terminating to power supply by comparator U1 power end and resistance R5；
Step 205, the earth terminal ground connection by the resistance R2 other end, the nonpolar electric capacity C2 other end and comparator U1.
The operation principle of switch power supply die mould output short circuit protection circuit of the present invention is：Circuit powered on moment, switch electricity
The output voltage V in sourceoIt is zero, the magnitude of voltage V of comparator U1 inverting input-1It is zero, comparator U1 input in the same direction leads to
Resistance R5 is crossed with the output end VCC of power supply to connect, now, the magnitude of voltage of comparator U1 input in the same directionDue to V+1>V-1, therefore comparator U1 output end output high level, i.e., described switch
The output end V-OUT output high level of supply voltage type output short circuit protection circuit 1, the input of PWM controlling and driving circuits 3
When detecting the output end V-OUT output high level of the switch power supply die mould output short circuit protection circuit 1, pulse letter is produced
Number normal work of driving BUCK converter circuits 2, the Switching Power Supply normal work.
After circuit working stability, it can be seen from superposition theorem, the magnitude of voltage of comparator U1 in-phase input endThe magnitude of voltage of comparator U1 inverting input(due to flowing through switching diode D2 electric current very little, switching diode D2 forward conduction voltage drop is very low,
Generally than output voltage VoIt is much smaller, thereforeCalculation formula in do not considering switching diode D2 just
To conduction voltage drop), due to the reasonable design of resistance R1, resistance R2, resistance R3, resistance R4 and resistance R5 parameters, V can be caused+2>
V-2, therefore comparator U1 output end output high level, i.e., the output of described switch power supply die mould output short circuit protection circuit 1
V-OUT output high level is held, the input of PWM controlling and driving circuits 3 detects the switch power supply die mould output short-circuit
During the output end V-OUT output high level of protection circuit 1, the normal work of pulse signal driving BUCK converter circuits 2, institute are produced
State Switching Power Supply normal work.
When there is short trouble in circuit, the output voltage V of Switching Power SupplyoIt is rapid to decline, comparator U1 homophase input
The magnitude of voltage at end also rapid decrease, and due to diode D2 unilateral conduction so that nonpolar electric capacity C2 can only be by by electricity
The loop of resistance R3, resistance R4 and nonpolar electric capacity C2 formation is discharged, so that comparator U1 anti-phase input terminal voltage is only
Can slowly it decline.Comparator U1 in-phase input end voltage ratio anti-phase inputs terminal voltage declines much faster, and now, comparator U1 is same
Phase input terminal voltage is less than anti-phase input terminal voltage, therefore comparator U1 output end output low level, i.e., described Switching Power Supply
The output end V-OUT output low levels of voltage-type output short circuit protection circuit 1, the input detection of PWM controlling and driving circuits 3
To the switch power supply die mould output short circuit protection circuit 1 output end V-OUT export low level when, shut-off pulse letter
Number, BUCK converter circuits 2 are stopped, i.e., Switching Power Supply is stopped, until output voltage drops to zero, comparator U1's
The magnitude of voltage of in-phase input end is changed intoWhile the voltage of comparator U1 inverting input
ValueWith UC2(t)Decline and reduce, but as long as meeting formula V+3<V-3When, comparator U1's is defeated
Go out end and export low level always, i.e., the output end V-OUT of described switch power supply die mould output short circuit protection circuit 1 exports low electricity
Flat, the input of PWM controlling and driving circuits 3 detects the output of the switch power supply die mould output short circuit protection circuit 1
When holding V-OUT output low levels, pulse signal is turned off, BUCK converter circuits 2 are still stopped, and Switching Power Supply still stops work
Make；With continuing for nonpolar electric capacity C2 discharge processes, the voltage at nonpolar electric capacity C2 two ends constantly reduces, when meeting formula V+3
>V-3When, comparator U1 output end output high level, i.e., the output of described switch power supply die mould output short circuit protection circuit 1
V-OUT output high level is held, the input of PWM controlling and driving circuits 3 detects the switch power supply die mould output short-circuit
During the output end V-OUT output high level of protection circuit 1, produce pulse signal driving BUCK converter circuits 2 and restart, i.e.,
The Switching Power Supply restarting, recovers normal work.
It is described above, only it is presently preferred embodiments of the present invention, not the present invention is imposed any restrictions, it is every according to the present invention
Any simple modification, change and equivalent structure change that technical spirit is made to above example, still fall within skill of the present invention
In the protection domain of art scheme.
Claims (3)
1. a kind of design method of switch power supply die mould output short circuit protection circuit, output short circuit protection circuit includes comparator
U1, switching diode D2 and nonpolar electric capacity C2, and resistance R1, resistance R2, resistance R3, resistance R4 and resistance R5；It is described to open
One end of the anode and resistance R1 that close diode D2 connects and is the switch power supply die mould output short circuit protection circuit (1)
Input V-IN, the input V-IN of the switch power supply die mould output short circuit protection circuit (1) and the positive pole of Switching Power Supply
Voltage output end connects, and the negative electrode of the switching diode D2 connects with nonpolar electric capacity C2 one end and resistance R3 one end,
The other end of the resistance R1 is grounded by resistance R2, the other end ground connection of the nonpolar electric capacity C2, and the resistance R3's is another
One end connects with comparator U1 inverting input, and is grounded by resistance R4, the connection end of the resistance R1 and resistance R2 with
And in-phase input end of the resistance R5 one end with comparator U1 connects, the power end of the comparator U1 and resistance R5's is another
End connects with the output end VCC of power supply, the earth terminal ground connection of the comparator U1, and the output end of the comparator U1 is
The output end V-OUT of the switch power supply die mould output short circuit protection circuit (1), the switch power supply die mould output short-circuit
The output end V-OUT of protection circuit (1) connects with the input of PWM controlling and driving circuits (3), it is characterised in that：The design
Method comprises the following steps：
Step 1: the nonpolar electric capacity C2 and resistance R1, resistance R2, resistance R3, resistance R4 and resistance R5 of selection suitable parameters,
Its detailed process is as follows：
Step 101, according to formulaChoose resistance R1's
The resistance of resistance, resistance R2 resistance and resistance R5, wherein, V+1For the electricity of circuit powered on moment comparator U1 in-phase input end
Pressure value, V+2For the magnitude of voltage of comparator U1 in-phase input end after circuit working stability, VCC is the output voltage of power supply,
VoFor the output voltage of Switching Power Supply；
Step 102, according to formulaResistance R3 resistance and resistance R4 resistance are chosen, wherein, V-2For electricity
The magnitude of voltage of comparator U1 inverting input after the working stability of road；
Step 103, first, according to formulaCalculating obtains Switching Power Supply because output short-circuit stops
The magnitude of voltage V of comparator U1 in-phase input end when being again started up after only working+3, then, according to formulaAnd according to nonpolar electric capacity C2 discharge time t=twWhenIt is derived by formulaFinally, according to formulaChoose nonpolar electric capacity C2 capacitance；Wherein,
V-3(t)The magnitude of voltage of comparator U1 inverting input when for nonpolar electric capacity C2 discharge time being t；For nonpolar electricity
The discharge time for holding C2 is twWhen, comparator U1's is anti-phase defeated when Switching Power Supply is again started up after being stopped due to output short-circuit
Enter the magnitude of voltage at end；twFor holding time for switch power supply die mould output short circuit protection circuit (1), UC2(t)For nonpolar electric capacity
Magnitude of voltage when C2 discharge time is t on nonpolar electric capacity C2,Discharge time for nonpolar electric capacity C2 is twShi Fei
Magnitude of voltage on polar capacitor C2, τ is nonpolar electric capacity C2 discharge time constant, and e is natural constant and takes e=2.71828；
Step 2: connection comparator U1, switching diode D2 and nonpolar electric capacity C2, and resistance R1, resistance R2, resistance R3,
Resistance R4 and resistance R5；Its detailed process is as follows：
Step 201, the cathode voltage output that one end of switching diode D2 anode and resistance R1 is all connected to Switching Power Supply
End；
Step 202, connecting valve diode D2 negative electrode, nonpolar electric capacity C2 one end and resistance R3 one end；
Step 203, the resistance R1 other end is connected with resistance R2 one end and resistance R5 one end and is followed by comparator U1's
In-phase input end；
Step 203, the resistance R3 other end is connected to the inverting input for being followed by comparator U1 with resistance R4 one end；
Step 204, another output end VCC for terminating to power supply by comparator U1 power end and resistance R5；
Step 205, the earth terminal ground connection by the resistance R2 other end, the nonpolar electric capacity C2 other end and comparator U1.
2. according to the design method of the switch power supply die mould output short circuit protection circuit described in claim 1, it is characterised in that：
The comparator U1 is made up of chip LM393, the output end that the output end of the comparator U1 passes through resistance R6 and power supply
VCC connects.
3. according to the design method of the switch power supply die mould output short circuit protection circuit described in claim 1, it is characterised in that：
The Switching Power Supply includes BUCK converter circuits (2), and the BUCK converter circuits (2) include PMOS switch pipe VT1, inductance
L1, switching diode D1 and polar capacitor C1, the PMOS switch pipe VT1 grid are defeated with PWM controlling and driving circuits (3)
Go out end to connect, the drain electrode of the PMOS switch pipe VT1 is the voltage input end Vi of Switching Power Supply, the PMOS switch pipe VT1's
Source electrode connects with switching diode D1 negative electrode and inductance L1 one end, and the other end and polar capacitor C1 of the inductance L1 are just
Pole connect and for Switching Power Supply cathode voltage output end vo+, the anode of the switching diode D1 and polar capacitor C1's is negative
Pole connect and for Switching Power Supply cathode voltage output end vo-, cathode voltage output end vo-ground connection of the Switching Power Supply, institute
State Switching Power Supply cathode voltage output end vo+and cathode voltage output end vo-between be connected to load RL.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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| CN105186459B (en) * | 2015-09-30 | 2018-03-06 | 广州金升阳科技有限公司 | The output short-circuit protection method and circuit of a kind of Switching Power Supply |
| CN109390916B (en) * | 2017-08-14 | 2024-06-25 | 河南理工大学 | Pulse tracking type power supply broadband short-circuit protection circuit |
| CN111103505A (en) * | 2020-01-13 | 2020-05-05 | 北京科锐配电自动化股份有限公司 | Adjustable short-circuit fault trigger circuit, control method thereof and computer readable storage medium |
| CN111614063B (en) * | 2020-05-26 | 2023-02-17 | 湖南晟和电源科技有限公司 | Short-circuit protection circuit and short-circuit protection system |
| CN113162384A (en) * | 2021-04-29 | 2021-07-23 | 中国电子科技集团公司第四十三研究所 | Overcurrent protection circuit of switching power supply |
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| CN201708696U (en) * | 2010-06-24 | 2011-01-12 | 复旦大学 | Buck converter circuit applicable to the continuous change of voltage of output power supply |
| CN102882380A (en) * | 2012-10-22 | 2013-01-16 | 广州三晶电气有限公司 | Multi-path output flyback power supply with output short-circuit protection function and protection method |
| CN103872890A (en) * | 2014-03-31 | 2014-06-18 | 广州视源电子科技股份有限公司 | Switching power supply circuit with short-circuit protection function |
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| DE60210217T2 (en) * | 2001-01-31 | 2006-11-16 | Matsushita Electric Industrial Co., Ltd., Kadoma | SMPS device |
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|---|---|---|---|---|
| CN201708696U (en) * | 2010-06-24 | 2011-01-12 | 复旦大学 | Buck converter circuit applicable to the continuous change of voltage of output power supply |
| CN102882380A (en) * | 2012-10-22 | 2013-01-16 | 广州三晶电气有限公司 | Multi-path output flyback power supply with output short-circuit protection function and protection method |
| CN103872890A (en) * | 2014-03-31 | 2014-06-18 | 广州视源电子科技股份有限公司 | Switching power supply circuit with short-circuit protection function |
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