CN208608726U - A kind of LDO output over-voltage protection structure not increasing quiescent current - Google Patents
A kind of LDO output over-voltage protection structure not increasing quiescent current Download PDFInfo
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- CN208608726U CN208608726U CN201821282581.2U CN201821282581U CN208608726U CN 208608726 U CN208608726 U CN 208608726U CN 201821282581 U CN201821282581 U CN 201821282581U CN 208608726 U CN208608726 U CN 208608726U
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Abstract
A kind of LDO output over-voltage protection structure not increasing quiescent current includes LDO main body, load resistance, output capacitance and overvoltage crowbar structure；LDO main body is made of error amplifier, power tube, feedforward compensation capacitor and resitstance voltage divider；Resitstance voltage divider is concatenated by resistance R1, R2；Overvoltage crowbar structure is made of NMOS tube N1, N2, N3, N4 and PMOS tube P1, P2；NMOS tube N1, N2, N3 are to be connected on output end in the form of diode connection, are used as zener diode；NMOS tube N3 and NMOS tube N4, PMOS tube P1 and PMOS tube P2 are respectively formed current-mirror structure；The number of output end concatenated NMOS tube N1, N2, N3 are determined by the overvoltage protection value of output voltage, are increased or decreased as needed.The utility model overvoltage crowbar structure division does not increase the quiescent current of LDO additionally, reduces the quiescent dissipation of LDO, extends the stand-by time of electronic product；When load restoration is to normal value, LDO loop restores to work normally the time needed shorter.
Description
Technical field
The utility model relates to a kind of LDO overvoltage crowbars, especially provide a kind of LDO output for not increasing quiescent current
Overvoltage protection structure.
Background technique
LDO (LOW DROPOUT LINER REGULATOR) is known as low pressure difference linear voltage regulator, due to its output voltage
The advantages that stable, noise is small, and quiescent dissipation is small, and peripheral components are few, is widely used in electronic system.But work as the load of LDO
Suddenly when decline, since feedback loop response speed is not fast enough, output voltage will appear overshoot phenomenon, if overshoot voltage is more than
The pressure-resistant range of subsequent electronics, will affect the service life of electronic device, subsequent electronics is damaged when serious.So
LDO usually has output overvoltage protection circuit, prevents output voltage overshoot too high.
Existing overvoltage protection scheme generally uses comparator, output voltage compared with reference voltage, works as output voltage
When more than setting value, overvoltage crowbar works, and limitation output voltage further increases.But the shortcomings that the method has itself:
As long as one, LDO works on power, comparator can all consume certain quiescent current, can be serious if comparator quiescent current is bigger
Influence the stand-by time of electronic product, this phenomenon low-power consumption, super low-power consumption mobile electronic product in it is especially serious, be electricity
The serious obstruction that sub- product develops to low-power consumption, super low-power consumption direction；Two, when since over-voltage occurs, overvoltage crowbar is function
Rate pipe is completely switched off, so when load restoration, the time that entire LDO loop restores normal work is longer, after influencing when serious
The working condition of continuous circuit.
Utility model content
To solve the above-mentioned problems, the purpose of the utility model is to provide it is a kind of be easily achieved, restore it is fast do not increase it is quiet
The LDO output over-voltage protection structure of state electric current.
In order to achieve the above objectives, the technical solution of the utility model is as follows: the LDO that one kind not increasing quiescent current was exported
Pressure protection structure, including LDO main body, load resistance (Rload), output capacitance (Cout) and overvoltage crowbar structure；
The LDO main body by error amplifier (ERROR AMP), power tube (Ppass), feedforward compensation capacitor (CFB) and
Resitstance voltage divider composition；The positive input of the error amplifier (ERROR AMP) terminates reference voltage, negative input termination output electricity
The feedback end of pressure, the grid of output termination power tube (Ppass)；The resitstance voltage divider is concatenated by resistance R1, R2, connection
Place forms the feedback end of output voltage, other end resistance R1 ground connection, and resistance R2 connects the drain electrode of power tube (Ppass)；The power
The source electrode of pipe (Ppass) connects power supply；The feedforward compensation capacitor (CFB) is connected across the both ends of resistance R2；
The load resistance (Rload) and the output capacitance (Cout) are in parallel, latter termination power pipe (Ppass) in parallel
Drain electrode, the other end ground connection；
The overvoltage crowbar structure is made of NMOS tube N1, N2, N3, N4 and PMOS tube P1, P2；The NMOS tube
N1, N2, N3 are to be connected on output end in the form of diode connection, are used as zener diode；The NMOS tube N3 and NMOS tube
N4, PMOS tube P1 and PMOS tube P2 are respectively formed current-mirror structure；The drain terminal of the PMOS tube P2 and the grid of power tube (Ppass)
Pole is connected, and source electrode connect with the source electrode of PMOS tube P1 and is followed by power supply, and drain electrode and the grid short circuit of the PMOS tube P1 is followed by
The drain electrode of NMOS tube N4, the source electrode of NMOS tube N3, N4 are grounded after being connected.
Further, the number of the output end concatenated NMOS tube N1, N2, N3 is determined by the overvoltage protection value of output voltage
It is fixed, it is increased or decreased as needed.
The beneficial effects of the utility model are: N1, N2, N3 pipe end when (1) works normally, so entire output voltage is protected
Protection circuit does not consume quiescent current, to reduce the quiescent dissipation of LDO, extends the stand-by time of electronic product, is suitable for low
Power consumption, the LDO design of super low-power consumption；(2) when output overvoltage, P1, which is managed, and P2 is tubular is mirrored into structure, and P2 pipe is put with error at this time
The input of big device forms push-pull output structure to pipe, and the conducting degree by reducing power tube limits the further liter of output voltage
Height, rather than power tube is ended completely, so when load restoration is to normal value, LDO loop, which restores to work normally, to be needed
Time is shorter.
Detailed description of the invention
Fig. 1 is the structure chart of the utility model；Fig. 2 is traditional LDO output overvoltage protection circuit structure chart.
Specific embodiment
Specific embodiment of the present utility model is described in detail with reference to the accompanying drawing.
As shown in Figure 1, a kind of LDO output over-voltage protection structure for not increasing quiescent current, including LDO main body, load electricity
Hinder (Rload), output capacitance (Cout) and overvoltage crowbar structure；The LDO main body is by error amplifier (ERROR
AMP), power tube (Ppass), feedforward compensation capacitor (CFB) and resitstance voltage divider composition；Error amplifier (the ERROR
AMP positive input) terminates reference voltage, and negative input terminates the feedback end of output voltage, the grid of output termination power tube (Ppass)
Pole drives power tube, to control load current；Power tube (Ppass) is controlled at error amplifier (ERROR AMP)
Under, export certain load current；Resistance R1, R2 composition resitstance voltage divider divide output voltage (VOUT), output
A part feedback of voltage (VOUT) arrives the negative input end of error amplifier (ERROR AMP), forms complete feedback loop,
The both ends that feedforward compensation capacitor (CFB) is connected across resistance R2 compensate feedback loop, improve the stabilization of feedback loop
Property.Entire LDO main body constitutes a feedback loop, according to the size of external loading electric current, error amplifier (ERROR AMP)
Grid (Pgate) voltage of power tube (Ppass) is adjusted, to keep stable output voltage.
The overvoltage crowbar structure is made of NMOS tube N1, N2, N3, N4 and PMOS tube P1, P2；The NMOS tube
N1, N2, N3 are to be connected on output end in the form of diode connection, are used as zener diode, concatenated NMOS tube N1, N2, N3
Number determined by the overvoltage protection value of output voltage, can according to need and increased or decreased, for determining output overvoltage
Protect preset value；The NMOS tube N3 and NMOS tube N4, PMOS tube P1 and PMOS tube P2 are respectively formed current-mirror structure；It is described
The drain terminal of PMOS tube P2 is connected with the grid of power tube (Ppass), and source electrode connect with the source electrode of PMOS tube P1 and is followed by power supply, institute
The drain electrode and grid for stating PMOS tube P1 are shorted the drain electrode for being followed by NMOS tube N4, and the source electrode of NMOS tube N3, N4 is grounded after being connected.
Its working principle is that be connected when output voltage is more than preset voltage value with NMOS tube N1, N2, N3 of diode type of attachment,
NMOS tube N3 and N4 are current-mirror structures, then NMOS tube N4 is connected, and PMOS tube P1, NMOS tube N4 branch have electric current to pass through, then
PMOS tube P2 conducting, the grid voltage of power tube (Ppass) is drawn high, overvoltage crowbar works, prevent output voltage into
One step increases.
The overvoltage crowbar working principle that this patent is related to is described in detail below.Its working principle is divided to two kinds
Situation:
The first situation: when chip normal work, not up to preset overpressure protection value, NMOS tube N1, N2, N3 cut-off,
Then PMOS tube P1, NMOS tube N4 branch do not have electric current to flow through, and PMOS tube P2 pipe cut-off, overvoltage crowbar does not work, at this time
Feedback control loop works, and error amplifier (ERROR_AMP) is to the grid voltage of power tube (Ppass) according to external loading electric current
Situation is adjusted, the output voltage that LDO can be stable, and output voltage is at this time:
--- --- --- --- --- -- (formula 1.1)
Second situation: load current ILOADReduce (Rload increases suddenly) suddenly, due to feedback loop response speed
Not fast enough, output voltage has overshoot, if output voltage overshoot is more than preset overpressure value, NMOS tube N1, N2, N3 pipe is led
Logical, NMOS tube N4, PMOS tube P1 branch have electric current to flow through, then PMOS tube P2 pipe is connected, the grid of power tube (Ppass)
(Pgate) voltage is raised by PMOS tube P2 pipe, and power tube (Ppass) is connected degree and reduces, and output overvoltage protection circuit rises
Effect, limitation output voltage further increase.
In circuit design, NMOS tube N1, N2, N3 pipe is usually arranged as down than pipe, and purpose is first is that make their gate source voltages
It is approximately equal to threshold voltage, convenient for determining preset overpressure value, second is that static working current increase is smaller when over-voltage occurs.
It is to be illustrated to the preferable implementation of the utility model, but the invention is not limited to the reality above
Example is applied, those skilled in the art can also make various equivalent variations without departing from the spirit of the present invention
Or replacement, these equivalent deformations or replacement are all included in the scope defined by the claims of the present application.
Claims (2)
1. the LDO output over-voltage protection structure that one kind does not increase quiescent current, it is characterised in that: including LDO main body, load resistance
(Rload), output capacitance (Cout) and overvoltage crowbar structure；
The LDO main body is by error amplifier (ERROR AMP), power tube (Ppass), feedforward compensation capacitor (CFB) and resistance
Divider composition；The positive input of the error amplifier (ERROR AMP) terminates reference voltage, and negative input terminates output voltage
Feedback end, the grid of output termination power tube (Ppass)；The resitstance voltage divider is concatenated by resistance R1, R2, junction shape
At the feedback end of output voltage, other end resistance R1 ground connection, resistance R2 connects the drain electrode of power tube (Ppass)；The power tube
(Ppass) source electrode connects power supply；The feedforward compensation capacitor (CFB) is connected across the both ends of resistance R2；
The load resistance (Rload) and the output capacitance (Cout) are in parallel, the leakage of latter termination power pipe (Ppass) in parallel
Pole, other end ground connection；
The overvoltage crowbar structure is made of NMOS tube N1, N2, N3, N4 and PMOS tube P1, P2；The NMOS tube N1, N2,
N3 is to be connected on output end in the form of diode connection, is used as zener diode；The NMOS tube N3 and NMOS tube N4, PMOS
Pipe P1 and PMOS tube P2 are respectively formed current-mirror structure；The drain terminal of the PMOS tube P2 is connected with the grid of power tube (Ppass)
It connects, source electrode connect with the source electrode of PMOS tube P1 and is followed by power supply, and the drain electrode of the PMOS tube P1 and grid short circuit are followed by NMOS tube N4
Drain electrode, the source electrode of NMOS tube N3, N4 is grounded after being connected.
2. the LDO output over-voltage protection structure that one kind according to claim 1 does not increase quiescent current, it is characterised in that:
The number of described output end concatenated NMOS tube N1, N2, N3 are determined by the overvoltage protection value of output voltage, are increased as needed
It adds deduct few.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821282581.2U CN208608726U (en) | 2018-08-09 | 2018-08-09 | A kind of LDO output over-voltage protection structure not increasing quiescent current |
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| CN201821282581.2U CN208608726U (en) | 2018-08-09 | 2018-08-09 | A kind of LDO output over-voltage protection structure not increasing quiescent current |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111796619A (en) * | 2020-06-28 | 2020-10-20 | 同济大学 | Circuit for preventing output voltage of low dropout linear regulator from overshooting |
| CN111857230A (en) * | 2020-08-11 | 2020-10-30 | 上海艾为电子技术股份有限公司 | Linear regulator and electronic device |
| CN117728366A (en) * | 2023-12-06 | 2024-03-19 | 无锡力芯微电子股份有限公司 | A quick overvoltage protection circuit for LDO |
-
2018
- 2018-08-09 CN CN201821282581.2U patent/CN208608726U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111796619A (en) * | 2020-06-28 | 2020-10-20 | 同济大学 | Circuit for preventing output voltage of low dropout linear regulator from overshooting |
| CN111796619B (en) * | 2020-06-28 | 2021-08-24 | 同济大学 | Circuit for preventing output voltage of low dropout linear regulator from overshooting |
| CN111857230A (en) * | 2020-08-11 | 2020-10-30 | 上海艾为电子技术股份有限公司 | Linear regulator and electronic device |
| CN117728366A (en) * | 2023-12-06 | 2024-03-19 | 无锡力芯微电子股份有限公司 | A quick overvoltage protection circuit for LDO |
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Effective date of registration: 20220608 Address after: 361011 units 704, 705 and 706, 7th floor, Wanxiang international business center 2 South Building, No. 1694, Gangzhong Road, Xiamen area, China (Fujian) pilot Free Trade Zone, Xiamen, Fujian Patentee after: XIAMEN XINYIDAI INTEGRATED CIRCUIT Co.,Ltd. Address before: Unit 305, integrated circuit industrial base, No. 1702, Gangzhong Road, Huli District, Xiamen, Fujian 361011 Patentee before: XIAMEN ASTSEMI TECHNOLOGY CO.,LTD. |
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