CN204271895U - A kind of boostrap circuit - Google Patents
A kind of boostrap circuit Download PDFInfo
- Publication number
- CN204271895U CN204271895U CN201420781905.2U CN201420781905U CN204271895U CN 204271895 U CN204271895 U CN 204271895U CN 201420781905 U CN201420781905 U CN 201420781905U CN 204271895 U CN204271895 U CN 204271895U
- Authority
- CN
- China
- Prior art keywords
- electric capacity
- voltage
- differential detection
- detection circuit
- connects
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Abstract
The utility model discloses a kind of boostrap circuit, comprising: electric capacity, two ends connect the driving stage circuit of a high-end switch pipe respectively, as the power supply of driving stage circuit, obtain one and go to drive high-end switch pipe using SW as the floating power supply of virtual earth; Differential detection circuit, two inputs connect the two ends of electric capacity respectively, in order to detect and the voltage difference at output capacitance two ends; Error amplifier or comparator, two inputs connect output and a reference voltage of differential detection circuit respectively, export corresponding error voltage or comparative voltage; P type pipe, gate terminal connects the output of error amplifier or comparator, and drain electrode end connects one end of electric capacity by diode.
Description
Technical field
The utility model relates to electronic circuit technology field, particularly a kind of boostrap circuit.
Background technology
High-end N type switch tube is widely used in various switch power supply topological structure, is also widely used in audio frequency power amplifier field.Because N type switch tube is under identical area condition, than P type pipe, there is less conducting resistance.But high-end N type switch tube is because near power supply, so need a driving voltage higher than supply voltage to go the grid level of driving N type switching tube N type switch tube thoroughly could be opened, thus play its advantage.So need boostrap circuit to produce a driving voltage higher than supply voltage.
Traditional boostrap circuit as shown in Figure 1, the PWM duty cycle signals wherein inputted, while go to drive low side N type switch tube MN0 by low side driving stage circuit, another side goes to drive high-end N type switch tube MN1 by level shift circuit and high-side driver level circuit, and electric capacity Cp provides the voltage needed for driving for high-end N type switch tube MN1.But when input voltage VIN is higher, the voltage so on electric capacity Cp also can be very high, equals VIN-Vd0, and Vd0 is the pressure drop of diode D0.Voltage on electric capacity Cp does not have regulating power, can only follow the change of VIN and change.So just high-side driver level circuit is needed to adopt corresponding high-voltage tube to realize.And high-voltage tube to realize the area that driving stage can make driving stage very large, thus add chip cost.Directly drive high-end N type switch tube MN1 with high pressure VIN in addition, the gate source voltage of so high-end N type switch tube MN1 is also wanted to bear high pressure, when reaching onesize conducting resistance, than the switching tube without the need to bearing grid source high pressure, area will go out greatly a lot.
Utility model content
The utility model is for prior art above shortcomings, and provide a kind of boostrap circuit, the utility model is achieved through the following technical solutions:
A kind of boostrap circuit, comprising:
Electric capacity, two ends connect the driving stage circuit of a high-end switch pipe respectively, as the power supply of driving stage circuit, obtain one and go to drive high-end switch pipe using SW as the floating power supply of virtual earth;
Differential detection circuit, two inputs of differential detection circuit connect the two ends of electric capacity respectively, in order to detect and the voltage difference at output capacitance two ends;
Error amplifier, two inputs of error amplifier connect output and a reference voltage of differential detection circuit respectively, export corresponding error voltage;
P type pipe, gate terminal connects the output of error amplifier, and drain electrode end connects wherein one end of electric capacity;
Diode, connects the drain electrode of P type pipe and one end of electric capacity, in order to prevent electric capacity by P type tube discharge.
Preferably, two inputs of differential detection circuit comprise positive input terminal and negative input end, and positive input terminal is connected between diode and the end of electric capacity, and negative input end connects the other end of electric capacity.
Preferably, two inputs of error amplifier comprise positive input terminal and negative input end, and positive input terminal connects the output of differential detection circuit, and negative input end connects reference voltage.
The utility model is for prior art above shortcomings, and separately provide a kind of boostrap circuit, the utility model is achieved through the following technical solutions:
A kind of boostrap circuit, comprising:
Electric capacity, two ends connect the driving stage circuit of a high-end switch pipe respectively, as the power supply of driving stage circuit, obtain one and go to drive high-end switch pipe using SW as the floating power supply of virtual earth;
Differential detection circuit, two inputs of differential detection circuit connect the two ends of electric capacity respectively, in order to detect and the voltage difference at output capacitance two ends;
Comparator, two inputs of comparator connect output and a reference voltage of differential detection circuit respectively, export corresponding comparative voltage;
P type pipe, gate terminal connects the output of comparator, and drain electrode end connects wherein one end of electric capacity;
Diode, connects the drain electrode of P type pipe and one end of electric capacity, in order to prevent electric capacity by P type tube discharge.
Preferably, two inputs of differential detection circuit comprise positive input terminal and negative input end, and positive input terminal is connected between diode and the end of electric capacity, and negative input end connects the other end of electric capacity.
Preferably, two inputs of comparator comprise positive input terminal and negative input end, and positive input terminal connects the output of differential detection circuit, and negative input end connects reference voltage.
In the utility model, because the voltage on electric capacity Cp can regulate, even if VIN is very high voltage, also can voltage on control capacitance Cp in lower level, and be a stable voltage, i.e. n*Vref.Do not change with VIN.Which improves the safe coefficient of chip, and reduce design difficulty.And driving stage also can adopt low-voltage circuit to design, and high-end switch pipe MN1 is also without the need to adopting the device that can bear high gate source voltage, thus greatly reduces the area of driving stage and high-end switch pipe MN1, reduces chip cost.
Accompanying drawing explanation
Shown in Fig. 1 is the circuit diagram of existing boostrap circuit;
Shown in Fig. 2 is the circuit diagram of the utility model first embodiment;
Shown in Fig. 3 is the working waveform figure of the utility model first embodiment;
Shown in Fig. 4 is the circuit diagram of the utility model second embodiment;
Shown in Fig. 5 is the working waveform figure of the utility model second embodiment.
Embodiment
Below with reference to accompanying drawing of the present utility model; clear, complete description and discussion are carried out to the technical scheme in the utility model embodiment; obviously; as described herein is only a part of example of the present utility model; it is not whole examples; based on the embodiment in the utility model, the every other embodiment that those of ordinary skill in the art obtain under the prerequisite not making creative work, all belongs to protection range of the present utility model.
For the ease of the understanding to the utility model embodiment, be further explained for specific embodiment below in conjunction with accompanying drawing, and each embodiment does not form the restriction to the utility model embodiment.
As shown in Figure 2, the two ends of electric capacity Cp connect the driving stage circuit of a high-end switch pipe MN1 respectively, as the power supply of driving stage circuit, obtain one and go to drive high-end switch pipe MN1 using SW as the floating power supply of virtual earth; Two inputs of differential detection circuit connect the two ends of electric capacity Cp respectively, in order to detect and the voltage difference at output capacitance Cp two ends; Error amplifier, two inputs connect output and a reference voltage of differential detection circuit respectively, export corresponding error voltage; P type pipe MP1, gate terminal connects the output of error amplifier, and drain electrode end connects one end of electric capacity by diode.
In the embodiment that the utility model provides, differential detection circuit detects the difference of BST and the SW voltage at electric capacity Cp two ends, equals Vsns, and error amplifier produces error voltage Verr control P type pipe MP1 by a reference voltage Vref and Vsns.Charged to electric capacity Cp by the source electrode of P type pipe MP1 from VIN, make Vsns voltage substantially equal Vref voltage.The voltage be now defined as on electric capacity Cp is Vp.Wherein Vp=n*Vsns=n*Vref.Wherein n can regulate (Vsns voltage is n/mono-of Vp voltage) as required in differential detection circuit.
Shown in Fig. 3 is the work wave of the boostrap circuit of the present embodiment, when PWM duty cycle signals is low, low-end switch pipe MN0 opens, and the voltage of SW end is close to GND voltage, now VIN is charged to electric capacity Cp by P type pipe MP1 and diode D1, makes Vsns substantially equal Vref voltage.When PWM duty cycle signals is high, high-end switch pipe MN1 opens.SW terminal voltage rises, and BST terminal voltage also rises due to the effect of electric capacity Cp, material is thus formed the effect of a bootstrapping.SW end constantly rises final close to VIN, and the voltage that on electric capacity Cp, BST holds is just close to VIN+Vp.This creates the terminal a driving voltage more taller than VIN, thoroughly open high-end switch pipe MN1.
The output voltage of error amplifier is a stable analog voltage, goes control P type pipe MP1 to produce stable charging current source, can to BST capacitor charging when SW point is low.So be also linear rising at the voltage of waveform B ST-SW corresponding to Fig. 3.
When PWM duty cycle signals uprises, low-end switch pipe NM0 turns off.In order to go to open high-end switch pipe MN1, so the BST end above electric capacity will to the gate charges of high-end switch pipe MN1, then high-end switch pipe MN1 opens, then SW end is just elevated to very close to the level of PVIN, and BST end is due to the gate charges to high-end switch pipe MN1, so the voltage on electric capacity is lower than fiducial value VP.Because now the SW end of the bottom crown of electric capacity has changed to VIN from ground, because the differential voltage on electric capacity is about VP, so after SW end rises to VIN, BST end just becomes VIN+VP, visible top crown voltage is higher than VIN, and the P type pipe MP1 now in boostrap circuit and diode D1 can not to capacitor charging.
When PWM duty cycle signals step-down, low-end switch pipe MN0 opens, and high-end switch pipe MN1 turns off, so SW terminal voltage step-down, and closely current potential.So the voltage of BST end also will get off, close to VP, but lower than VP, now during VIN voltage higher than VP's, so P type pipe MP1 in boostrap circuit and diode D1 just can charge to electric capacity Cp, the voltage on electric capacity Cp (average voltage) has been made to remain on VP.So repeatedly.
The concrete voltage of SW is with the conducting resistance of MN1/0 and current related.When high-end switch pipe MN1 opens, SW=VIN-Ron1*I, wherein Ron1 is the conducting resistance of MN1, and I is the electric current flow through.When low-end switch pipe MN0 opens, SW=Ron0*I, Ron0 are the conducting resistance of MN0, and I is the electric current flow through.
Diode D1 conducting when VIN charges to electric capacity Cp, ends when BST terminal voltage equals VIN+Vp, prevents BST terminal voltage by P type pipe MP1 oppositely to VIN electric discharge, thus loses the effect of bootstrapping.It also can replace with the triode of a diode-connected, and the utility model does not limit.
In the process opening high-end switch pipe MN1, electric capacity Cp is to the gate discharge of high-end switch pipe MN1, thus loss Partial charge makes voltage on electric capacity Cp lower than VP.So at next cycle, when SW holds step-down again close to GND voltage, VIN is charged by P type pipe MP1 and diode D1 again, makes the average voltage of electric capacity Cp return to VP.So go round and begin again, realize bootstrapping.
As shown in Figure 4, in the second embodiment of the present utility model, comparator is adopted to replace error amplifier.Differential detection circuit detects the difference of BST and the SW voltage at electric capacity Cp two ends, and (and having made n convergent-divergent doubly), equals Vsns, i.e. Vsns=Vp/n, and comparator produces comparative voltage Vcon control P type pipe MP1 by reference to voltage Vref and Vsns.
Shown in Fig. 5 is the work wave of the boostrap circuit of the present embodiment,
When PWM duty cycle signals is low, low-end switch pipe MN0 opens, SW terminal voltage is close to GND voltage, and now Vsns voltage is lower than reference voltage Vref, comparative voltage Vcon step-down, P type pipe MP1 opens, VIN is charged to electric capacity Cp by P type pipe MP1 and diode D1, and when Vsns voltage is higher than reference voltage Vref, comparative voltage Vcon uprises, P type pipe MP1 turns off, and VIN stops charging to electric capacity Cp.When PWM duty cycle signals is high, high-end switch pipe MN1 opens.SW terminal voltage rises, and BST terminal voltage also rises due to the effect of electric capacity Cp, material is thus formed the effect of a bootstrapping.SW end constantly rises final close to VIN, and the voltage that on electric capacity Cp, BST holds is just close to VIN+Vp.This creates the terminal a driving voltage more taller than VIN, thoroughly open high-end switch pipe MN1.
The general principle of the present embodiment is identical with the first embodiment, just different on charging modes.
After high-end switch pipe MN1 opens, because high-end switch pipe charges to MN1, the voltage on electric capacity Cp reduces, the now output of comparator step-down, opens P type pipe MP1, prepares to charge to electric capacity Cp, but because the electric capacity of BST end is higher than VIN, so now do not fill electricity.When high-end switch pipe MN1 turns off, low-end switch pipe MN0 opens, and after SW holds step-down, P type pipe MP1 charges to electric capacity Cp at once, because at this moment P type pipe MP1 opens completely, conducting resistance is very little, so charging current is large, electric capacity Cp is filled up very soon, be charged to the place just over VP, comparator exports and just uprises, and turns off P type pipe MP1 pipe, no longer charges to electric capacity Cp.Equally also be the average voltage maintained on electric capacity Cp be VP.Also be so repeatedly work.
Diode D1 conducting when VIN charges to electric capacity Cp, ends when BST terminal voltage equals VIN+Vp, prevents BST terminal voltage by P type pipe MP1 oppositely to VIN electric discharge, thus loses the effect of bootstrapping.It also can replace with the triode of a diode-connected, and the utility model does not limit.
In the process opening high-end switch pipe MN1, electric capacity Cp discharges to high-end switch pipe MN1, thus loss Partial charge makes voltage on electric capacity Cp lower than VP.So at next cycle, when SW holds step-down again close to GND voltage, VIN is charged by P type pipe MP1 and diode D1 again, makes its voltage resume to VP.So go round and begin again, realize bootstrapping.
It should be noted that, in two embodiments of the present utility model, high-end switch pipe MN1 and low-end switch pipe MN0 is N type switch tube, but the utility model can be applied in P type switching tube equally, also have in bipolar bipolar transistor, not as limit.
Above; be only the utility model preferably embodiment; but protection range of the present utility model is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the utility model discloses; the change that can expect easily or replacement, all should be encompassed within protection range of the present utility model.Therefore, protection range of the present utility model should be as the criterion with the protection range of claim.
Claims (6)
1. a boostrap circuit, is characterized in that, comprising:
Electric capacity, two ends connect the driving stage circuit of a high-end switch pipe, as the power supply of described driving stage circuit;
Differential detection circuit, two inputs of described differential detection circuit connect the two ends of described electric capacity respectively, in order to detect and to export the voltage difference at described electric capacity two ends;
Error amplifier, two inputs of described error amplifier connect output and a reference voltage of described differential detection circuit respectively, export corresponding error voltage;
P type pipe, gate terminal connects the output of described error amplifier, and drain electrode end connects wherein one end of described electric capacity;
Diode, connects the described drain electrode of P type pipe and one end of described electric capacity, in order to prevent described electric capacity by described P type tube discharge.
2. boostrap circuit according to claim 1, it is characterized in that, two inputs of described differential detection circuit comprise positive input terminal and negative input end, and described positive input terminal is connected between described diode and the described end of described electric capacity, and described negative input end connects the other end of described electric capacity.
3. boostrap circuit according to claim 1, is characterized in that, two inputs of described error amplifier comprise positive input terminal and negative input end, and described positive input terminal connects the output of described differential detection circuit, and described negative input end connects described reference voltage.
4. a boostrap circuit, is characterized in that, comprising:
Electric capacity, two ends connect the driving stage circuit of a high-end switch pipe respectively, as the power supply of described driving stage circuit;
Differential detection circuit, two inputs of described differential detection circuit connect the two ends of described electric capacity respectively, in order to detect and to export the voltage difference at described electric capacity two ends;
Comparator, two inputs of described comparator connect output and a reference voltage of described differential detection circuit respectively, export corresponding comparative voltage;
P type pipe, gate terminal connects the output of described comparator, and drain electrode end connects wherein one end of described electric capacity;
Diode, connects the described drain electrode of P type pipe and one end of described electric capacity, in order to prevent described electric capacity by described P type tube discharge.
5. boostrap circuit according to claim 4, it is characterized in that, two inputs of described differential detection circuit comprise positive input terminal and negative input end, and described positive input terminal is connected between described diode and the described end of described electric capacity, and described negative input end connects the other end of described electric capacity.
6. boostrap circuit according to claim 4, is characterized in that, two inputs of described comparator comprise positive input terminal and negative input end, and described positive input terminal connects the output of described differential detection circuit, and described negative input end connects described reference voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420781905.2U CN204271895U (en) | 2014-12-12 | 2014-12-12 | A kind of boostrap circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420781905.2U CN204271895U (en) | 2014-12-12 | 2014-12-12 | A kind of boostrap circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN204271895U true CN204271895U (en) | 2015-04-15 |
Family
ID=52806740
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420781905.2U Active CN204271895U (en) | 2014-12-12 | 2014-12-12 | A kind of boostrap circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN204271895U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104467371A (en) * | 2014-12-12 | 2015-03-25 | 上海数明半导体有限公司 | Bootstrap circuit |
| CN110071634A (en) * | 2018-01-23 | 2019-07-30 | 晶豪科技股份有限公司 | Bootstrap mode circuit and the associated DC to DC converter for using the circuit |
-
2014
- 2014-12-12 CN CN201420781905.2U patent/CN204271895U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104467371A (en) * | 2014-12-12 | 2015-03-25 | 上海数明半导体有限公司 | Bootstrap circuit |
| CN110071634A (en) * | 2018-01-23 | 2019-07-30 | 晶豪科技股份有限公司 | Bootstrap mode circuit and the associated DC to DC converter for using the circuit |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103647440B (en) | A kind of soft starting circuit and comprise the DC-DC circuit of this soft starting circuit | |
| CN102136800B (en) | Switching regulaor | |
| CN204349778U (en) | LED drive circuit and switch power controller thereof | |
| CN104467427A (en) | Switching control circuit and method for four-tube Buck-Boost converter | |
| CN104486891A (en) | Led drive circuit and constant current driver | |
| CN104467373A (en) | LED drive circuit and switching power controller thereof | |
| CN100483908C (en) | Pulse-frequency modulation DC/DC booster converter | |
| CN102386893A (en) | Adjustable square signal generation circuit and switch-type regulator utilizing same | |
| CN204271895U (en) | A kind of boostrap circuit | |
| CN204794681U (en) | Reduce DC -DC circuit that restarts repeatedly when falling electricity | |
| CN204291527U (en) | LED drive circuit and constant-current driver | |
| CN102123553B (en) | COT mode LED lighting driving circuit | |
| CN202384784U (en) | Charging management circuit | |
| CN107592011A (en) | A kind of charge pump system and three dimensional NAND memory | |
| CN104467371A (en) | Bootstrap circuit | |
| CN102739029A (en) | Soft start circuit for realizing large-current start of switching power supply | |
| CN104935154A (en) | Bootstrap circuit of step-down converter | |
| CN108711918A (en) | A kind of switched charge circuit | |
| CN205039703U (en) | Intelligence step -down formula switching power supply | |
| CN208754024U (en) | A kind of switched charge circuit | |
| CN104300783B (en) | A kind of regulating circuit and array base palte | |
| CN207251470U (en) | A kind of adaptive structure BUCK control devices | |
| CN204835903U (en) | Boostrap circuit of step -down converter | |
| CN204392088U (en) | A kind of voltage stabilizing circuit of adjustable voltage | |
| CN205453486U (en) | Novel switching power supply delays starting circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |