CN109842093A - A kind of undervoltage lockout circuit and switching power source chip - Google Patents
A kind of undervoltage lockout circuit and switching power source chip Download PDFInfo
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- CN109842093A CN109842093A CN201910232552.8A CN201910232552A CN109842093A CN 109842093 A CN109842093 A CN 109842093A CN 201910232552 A CN201910232552 A CN 201910232552A CN 109842093 A CN109842093 A CN 109842093A
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- 230000008569 process Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
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Abstract
The invention discloses a kind of undervoltage lockout circuit and switching power source chip, which includes: undervoltage lockout circuit input terminal, undervoltage lockout circuit output end, resistance R1, resistance R2, resistance R3, resistance R4, resistance R5, resistance R6, PMOS tube M1, PMOS tube M2, NMOS tube M3, NMOS tube M4, Schmidt trigger.Undervoltage lockout circuit of the invention utilizes the lagging characteristics of Schmidt trigger, realize that the shutdown voltage of circuit is much smaller than the starting voltage of circuit, the undervoltage lockout circuit structure is simple, fast response time, and without reference to structures such as reference source circuit, complicated comparison circuits, circuit layout area can be effectively reduced, manufacturing cost is saved.
Description
Technical field
The present invention relates to technical field of integrated circuits, in particular to a kind of undervoltage lockout circuit and switching power source chip.
Background technique
In integrated circuit design, keep stable switch power source output voltage particularly important, wherein switching power source chip
In undervoltage lockout circuit just be used to improve the safety of power supply, reliability and stability.When chip powers on, since power supply is defeated
Enter end there are equivalent resistance, capacitor etc., supply voltage has the process of a rising, when supply voltage reaches opening for circuit system
When dynamic voltage, circuit system is started to work, but can be circuit both ends if the load current of system is excessive opening moment
Voltage draw to starting voltage hereinafter, if at this time shutdown voltage be equal to starting voltage, just will appear once start turn off the case where.
In order to work normally after guaranteeing circuit start, shutdown voltage must be much smaller than starting voltage.And traditional undervoltage lockout circuit
There is a problem of that biggish quiescent dissipation, response speed are slow.
Summary of the invention
In view of the deficiencies of the prior art, it is an object of the present invention to provide a kind of fast response times, can effectively reduce quiet
The undervoltage lockout circuit of state power consumption.It is adopted the following technical scheme that
A kind of undervoltage lockout circuit, comprising: undervoltage lockout circuit input terminal, undervoltage lockout circuit output end, resistance R1, electricity
Hinder R2, resistance R3, resistance R4, resistance R5, resistance R6, PMOS tube M1, PMOS tube M2, NMOS tube M3, NMOS tube M4, Schmidt's touching
Send out device；
Undervoltage lockout circuit input terminal connects to power supply, the first end of resistance R1, the source electrode of PMOS tube M1, resistance R5
One end, PMOS tube M2 source electrode connect with undervoltage lockout circuit input terminal, the first end of resistance R6, the drain electrode of NMOS tube M2 are equal
Connect with the second end of resistance R5, the grid of PMOS tube M1, the drain electrode of NMOS tube M3, Schmidt trigger input terminal with electricity
The second end connection of R6 is hindered, the grid of PMOS tube M2 and the second output terminal of Schmidt trigger connect, the second end of resistance R1,
The first end of resistance R2 is connect with the drain electrode of PMOS tube M1, and the second end of resistance R2, the first end of resistance R3 are and NMOS tube
The grid of M3 connects, and the drain electrode of NMOS tube M4, the first end of resistance R4 are connect with the second end of resistance R3, and the second of resistance R4
End, the source electrode of NMOS tube M3, NMOS tube M4 source electrode connect with ground potential, the grid of NMOS tube M4 and Schmidt trigger
First output end of the connection of the first output end, undervoltage lockout circuit output end and Schmidt trigger connects.
It as a further improvement of the present invention, further include zener diode D1, the second end and zener diode of resistance R1
The cathode of D1 connects, and the first end of resistance R2, the drain electrode of PMOS tube M1 are connect with the anode of zener diode D1.
It as a further improvement of the present invention, further include zener diode D2, the leakage of the second end, PMOS tube M1 of resistance R1
It is extremely connect with the cathode of zener diode D2, the first end of resistance R2 is connect with the anode of zener diode D2.
The second purpose of the present invention is to provide a kind of switching power source chips, and it includes above-mentioned undervoltage lockout circuits.
Beneficial effects of the present invention:
1, undervoltage lockout circuit of the invention utilizes the lagging characteristics of Schmidt trigger, realizes that the shutdown voltage of circuit is remote
Less than the starting voltage of circuit.
2, undervoltage lockout circuit structure of the invention is simple, fast response time, and without reference to reference source circuit, complicated
The structures such as comparison circuit can effectively reduce circuit layout area, save manufacturing cost.
The above description is only an overview of the technical scheme of the present invention, in order to better understand the technical means of the present invention,
And it can be implemented in accordance with the contents of the specification, and in order to allow above and other objects, features and advantages of the invention can
It is clearer and more comprehensible, it is special below to lift preferred embodiment, and cooperate attached drawing, detailed description are as follows.
Detailed description of the invention
Fig. 1 is the circuit diagram of undervoltage lockout circuit in the embodiment of the present invention one.
Specific embodiment
The present invention will be further explained below with reference to the attached drawings and specific examples, so that those skilled in the art can be with
It more fully understands the present invention and can be practiced, but illustrated embodiment is not as a limitation of the invention.
Embodiment one
As shown in Figure 1, the undervoltage lockout circuit includes under-voltage locking for the undervoltage lockout circuit in the embodiment of the present invention one
Circuit input end Vin, undervoltage lockout circuit output end UVLO, resistance R1, resistance R2, resistance R3, resistance R4, resistance R5, resistance
R6, PMOS tube M1, PMOS tube M2, NMOS tube M3, NMOS tube M4, Schmidt trigger.
Undervoltage lockout circuit input terminal Vin is connected to power supply, the first end of resistance R1, the source electrode of PMOS tube M1, resistance R5
First end, PMOS tube M2 source electrode connect with undervoltage lockout circuit input terminal, the leakage of the first end, PMOS tube M2 of resistance R6
It is extremely connect with the second end of resistance R5, the grid of PMOS tube M1, the drain electrode of NMOS tube M3, the input of Schmidt trigger smit
End in is connect with the second end of resistance R6, and the grid of PMOS tube M2 and the second output terminal nout of Schmidt trigger smit connect
It connects, the second end of resistance R1, the first end of resistance R2 are connect with the drain electrode of PMOS tube M1, the second end of resistance R2, resistance R3
First end connect with the grid of NMOS tube M3, the drain electrode of NMOS tube M4, resistance R4 first end with resistance R3 second
End connection, the second end of resistance R4, the source electrode of NMOS tube M3, NMOS tube M4 source electrode connect with ground potential Gnd, NMOS tube M4
Grid connect with the first output end out of Schmidt trigger smit, undervoltage lockout circuit output end and Schmidt trigger
The first output end out connection.
In the present embodiment, which further includes zener diode D1, the second end and pressure stabilizing two of resistance R1
The cathode of pole pipe D1 connects, and the first end of resistance R2, the drain electrode of PMOS tube M1 are connect with the anode of zener diode D1.
In the present embodiment, which further includes zener diode D2, the second end of resistance R1, PMOS tube M1
Drain electrode connect with the cathode of zener diode D2, the first end of resistance R2 is connect with the anode of zener diode D2.
Since there are equivalent inpnt resistance, capacitor, undervoltage lockout circuit input terminal Vin by undervoltage lockout circuit input terminal Vin
Voltage can exist a process slowly risen, when input voltage rise to starting voltage (vddon) when, undervoltage lockout circuit
The start-up operation of enable signal control system can be issued.
Wherein, resistance R1, resistance R2, resistance R3, resistance R4 constitute sample circuit, and resistance R1, R2, R3, R4 are to under-voltage lock
Determine circuit input end Vin voltage and carry out partial pressure sampling, Ve is sampled voltage.When Ve is less than the threshold voltage of NMOS tube M3,
NMOS tube M3 is in an off state, and the voltage of the input terminal in of Schmidt trigger smit is undervoltage lockout circuit input terminal Vin
Voltage, at this point, PMOS tube M1 is in an off state, the output level of undervoltage lockout circuit output end ULVO is high level, electricity
Pressure numerical value follows undervoltage lockout circuit input terminal Vin voltage change, is equal to when undervoltage lockout circuit input terminal Vin voltage rises to
When the threshold voltage of NMOS tube M4, NMOS tube M4 is in the conductive state.On continuing with undervoltage lockout circuit input terminal Vin voltage
It rises, when Ve is equal to the threshold voltage of NMOS tube M3, NMOS tube M3 is in the conductive state, Schmidt trigger smit input terminal in
Voltage be pulled down to ground potential Gnd, undervoltage lockout circuit output end UVLO becomes low level, after undervoltage lockout circuit is controllable
Continuous circuit system is started to work, at this point, PMOS tube M2, NMOS tube M4 are in off state, PMOS tube M1 is on shape
State.Start voltage vddon about are as follows:
Wherein, due to the lagging characteristics of Schmidt trigger smit, vth_on is slightly larger than the threshold voltage of NMOS tube M3,
R1, R2, R3 are respectively the resistance value of resistance R1, resistance R2, resistance R3, VZ1For the pressure stabilizing value of voltage-stabiliser tube D1, VZ2For zener diode
The pressure stabilizing value of D2.
In undervoltage lockout circuit power process, the voltage of undervoltage lockout circuit input terminal Vin is reduced by supply voltage VDD
To ground potential Gnd.When the voltage of undervoltage lockout circuit input terminal Vin drops to shutdown voltage vddoff, undervoltage lockout circuit
Output enable signal control system can be changed to stop working.It is closed when the voltage of undervoltage lockout circuit input terminal Vin is greater than or equal to
When power-off pressure vddoff, undervoltage lockout circuit output end UVLO is low level, the second output terminal of Schmidt trigger smit
Nout is high level, and PMOS tube M2, NMOS tube M4 are in an off state, and PMOS tube M1 is in the conductive state.When under-voltage locking electricity
When road input terminal Vin is less than shutdown voltage vddoff, sampled voltage Ve is less than the threshold voltage of NMOS tube M3, and NMOS tube M3 is closed
Disconnected, the voltage of Schmidt trigger smit input terminal in increases to the voltage of undervoltage lockout circuit input terminal Vin, under-voltage locking electricity
Road output end UVLO becomes high level, and numerical value follows pressure lock-in circuit input terminal Vin variation, and PMOS tube M1 is off shape
State, PMOS tube M2, NMOS tube M4 are on state.Turn off voltage vddoff about are as follows:
Wherein, due to the lagging characteristics of Schmidt trigger, vth_off is slightly smaller than the threshold voltage of NMOS tube M3, R2,
R3, R4 are respectively the resistance value of resistance R2, resistance R3, resistance R4, VZ2For the pressure stabilizing value of zener diode D2.
By the way that the resistance value of different R1, R2, R3, R4 and the pressure stabilizing value of zener diode D1, zener diode D2 is arranged,
It can obtain the value of the starting voltage vddon of different demands and shutdown voltage vddoff suitable for example.
When undervoltage lockout circuit works normally, when the voltage of undervoltage lockout circuit input terminal Vin is lower than shutdown voltage
When vddoff, undervoltage lockout circuit understands other modules in turning off system, guarantees that the fluctuation of input voltage will not be to whole system
It damages.
Embodiment two
A kind of switching power source chip is proposed in the embodiment of the present invention two, which includes in embodiment one
Undervoltage lockout circuit.
Beneficial effects of the present invention:
1, undervoltage lockout circuit of the invention utilizes the lagging characteristics of Schmidt trigger, realizes that the shutdown voltage of circuit is remote
Less than the starting voltage of circuit.
2, undervoltage lockout circuit structure of the invention is simple, fast response time, and without reference to reference source circuit, complicated
The structures such as comparison circuit can effectively reduce circuit layout area, save manufacturing cost.
3, undervoltage lockout circuit of the invention has concatenated zener diode D1 and zener diode D2 in sample circuit, by
It is very small in the reverse-conducting bias current of zener diode, the starting current of circuit can be effectively reduced, to reduce circuit
Power consumption.
Above embodiments are only to absolutely prove preferred embodiment that is of the invention and being lifted, and protection scope of the present invention is not
It is limited to this.Those skilled in the art's made equivalent substitute or transformation on the basis of the present invention, in guarantor of the invention
Within the scope of shield.Protection scope of the present invention is subject to claims.
Claims (4)
1. a kind of undervoltage lockout circuit characterized by comprising undervoltage lockout circuit input terminal, undervoltage lockout circuit output end,
Resistance R1, resistance R2, resistance R3, resistance R4, resistance R5, resistance R6, PMOS tube M1, PMOS tube M2, NMOS tube M3, NMOS tube
M4, Schmidt trigger；
Undervoltage lockout circuit input terminal connects to power supply, the first end of resistance R1, the source electrode of PMOS tube M1, resistance R5 first
End, PMOS tube M2 source electrode connect with undervoltage lockout circuit input terminal, the first end of resistance R6, PMOS tube M2 drain electrode with
The second end of resistance R5 connects, the grid of PMOS tube M1, the drain electrode of NMOS tube M3, Schmidt trigger input terminal and resistance
The second end of R6 connects, and the grid of PMOS tube M2 and the second output terminal of Schmidt trigger connect, the second end of resistance R1, electricity
The first end of resistance R2 is connect with the drain electrode of PMOS tube M1, the second end of resistance R2, the first end of resistance R3 with NMOS tube M3
Grid connection, the drain electrode of NMOS tube M4, the first end of resistance R4 connect with the second end of resistance R3, the second of resistance R4
End, the source electrode of NMOS tube M3, NMOS tube M4 source electrode connect with ground potential, the grid of NMOS tube M4 and Schmidt trigger
First output end of the connection of the first output end, undervoltage lockout circuit output end and Schmidt trigger connects.
2. undervoltage lockout circuit as described in claim 1, which is characterized in that it further include zener diode D1, the of resistance R1
Two ends are connect with the cathode of zener diode D1, and the drain electrode of the first end, PMOS tube M1 of resistance R2 is with zener diode D1's
Anode connection.
3. undervoltage lockout circuit as described in claim 1, which is characterized in that it further include zener diode D2, the of resistance R1
The drain electrode at two ends, PMOS tube M1 is connect with the cathode of zener diode D2, and the first end of resistance R2 is with zener diode D2's
Anode connection.
4. a kind of switching power source chip, which is characterized in that include undervoltage lockout circuit a method according to any one of claims 1-3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910232552.8A CN109842093A (en) | 2019-03-26 | 2019-03-26 | A kind of undervoltage lockout circuit and switching power source chip |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910232552.8A CN109842093A (en) | 2019-03-26 | 2019-03-26 | A kind of undervoltage lockout circuit and switching power source chip |
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| CN109842093A true CN109842093A (en) | 2019-06-04 |
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| CN201910232552.8A Pending CN109842093A (en) | 2019-03-26 | 2019-03-26 | A kind of undervoltage lockout circuit and switching power source chip |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114815956A (en) * | 2022-06-10 | 2022-07-29 | 电子科技大学 | Under-voltage locking circuit suitable for gate drive |
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