CN100521479C - Low voltage start circuit for synchronous pressure-boosting converter and method thereof - Google Patents
Low voltage start circuit for synchronous pressure-boosting converter and method thereof Download PDFInfo
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- CN100521479C CN100521479C CNB2007100904025A CN200710090402A CN100521479C CN 100521479 C CN100521479 C CN 100521479C CN B2007100904025 A CNB2007100904025 A CN B2007100904025A CN 200710090402 A CN200710090402 A CN 200710090402A CN 100521479 C CN100521479 C CN 100521479C
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Abstract
A low voltage starting circuit of synchronization voltage increase converter of the invention comprises a P type power transistor, a N type power transistor and a controller. The low voltage circuit is connected with a voltage source by an inductor. The P type power transistor comprises a parasitic diode, one end of the P type power transistor is as the power supply of the oscillator. The N type power transistor is connected in series to the P type power transistor, which are not conducting at the same time. The controller is electrically connected with the oscillator which conducts the P type power transistor when in the initial state, then conducts the N type power transistor after delaying for a while of the initial state.
Description
Technical field
The invention relates to voltage starting circuit and the method thereof of a kind of boost converter (DC/DC Converter), especially refer to a kind of low voltage start circuit and method thereof of synchronous pressure-boosting converter.
Background technology
Fig. 1 is the start-up circuit of the boost converter of a routine, and wherein said start-up circuit makes the system voltage source V of the analog IC 10 shared described boost converters that comprise a N type power transistor
IN, 1.2 of battery volts of voltages for example.As described system voltage source V
INStart in low-voltage state (for example being lower than 0.9 volt),, and make output end voltage V because oscillator is not subjected to FEEDBACK CONTROL
OUTCan increase till dispersing fast.
Fig. 2 is the low voltage start circuit of another conventional boost converter, and it is with output end voltage V
OUTFeed back to comprise a N type power transistor analog IC 20 as supply voltage, to avoid aforesaid divergence problem.Because an end LX of inductor is connected to the output V of described boost converter with a Zener diode (Zenor diode)
OUTEven if, so described system voltage source V
INHave only 0.8 volt, see through the conducting voltage (about 0.1 volt) of described Zener diode, still can make the output V of described boost converter
OUTKeep about 0.7 volt voltage, and be enough to make described analog IC 20 to start smoothly.Yet the described custom circuit of Fig. 2 needs the extra Zener diode that increases, and therefore causes the rising of cost and the increase of chip area.
Therefore and do not meet present designer trends in addition, above-mentioned two kinds of custom circuits are the asynchronous circuit that only utilizes N type power transistor, rather than the do not overlap each other synchronous circuit of (non-overlapping) of quarter-phase and phase place.
Fig. 3 is the low voltage start circuit of the synchronous pressure-boosting converter of a routine.Described low voltage start circuit 30 is connected to voltage source V by inductor L1
INDescribed P type power transistor 32 comprises parasitic diode 33, and an end of described P type power transistor is connected to the output V of described synchronous pressure-boosting converter
OUT, and described output V
OUTCan be used as the power supply input of an oscillator.With regard to described parasitic diode 33,, can reduce the conducting voltage of described parasitic diode 33 so if use larger area P type power transistor 32.Yet use larger area P type power transistor 32 but to cause the improper increase of whole chip area.Be two kinds of factors more than the balance, the conducting voltage of described parasitic diode 33 can be controlled between 0.3 to 0.4 volt usually.Yet this moment voltage source V
INStarting resistor promptly must arrive between 1 to 1.1 volt and just be enough to integrated circuit is started smoothly.But for many application, system voltage source V
INOften be required promptly need start at 0.9 volt, therefore described low voltage start circuit 30 does not meet the demand on the market yet.
Summary of the invention
Circuit of the present invention and its method are to utilize the design of synchronous circuit, for effectively solving the problem of boost converter when low-voltage starts.
One embodiment of the low voltage start circuit of synchronous pressure-boosting converter of the present invention comprises P type power transistor, N type power transistor and controller.Described low voltage start circuit is connected to voltage source by inductor.Described P type power transistor comprises parasitic diode, and an end of described P type power transistor is connected to the power supply input of oscillator.Described N type power transistor is connected in series to described P type power transistor.Described controller is electrically connected to described oscillator, it comprises delay cell and logical block, wherein said logical block is the described P type of conducting power transistor when initial condition, and described delay cell conducting described N type power transistor and close described P type power transistor after one period time of delay of initial condition.
Another embodiment of the low voltage start circuit of synchronous pressure-boosting converter of the present invention comprises P type power transistor, N type power transistor and controller.The low voltage start circuit of described synchronous pressure-boosting converter is connected to voltage source by inductor.Described P type power transistor comprises parasitic diode, and the one end is connected to the power supply input of oscillator.Described N type power transistor is connected in series to described P type power transistor, wherein said P type power transistor and the not conducting simultaneously of described N type power transistor.Described controller is electrically connected to described oscillator, and it starts described P type power transistor when initial condition, and starts described N type power transistor after one period time of delay of initial condition.
Method of the present invention comprises provides the P of polyphone type power transistor and N type power transistor, and it is connected to voltage source by inductor, and an end of described P type power transistor is connected to the power supply input of oscillator.Secondly, the input low-voltage starts described oscillator to described voltage source by described P type power transistor.Subsequently, described oscillator just cuts out described P type power transistor after starting a period of time, and allows described N type power transistor operate as normal.
Description of drawings
Fig. 1 is conventional circuit diagram;
Fig. 2 is another conventional circuit diagram;
Fig. 3 is another conventional circuit diagram;
Fig. 4 is the schematic diagram of circuit of the present invention;
Fig. 5 (a) is an embodiment of circuit of the present invention; And
Fig. 5 (b) is the sequential chart of Fig. 5 (a).
Embodiment
Fig. 4 is the schematic diagram of the low voltage start circuit of synchronous pressure-boosting converter of the present invention.Described low voltage start circuit 40 comprises P type power transistor 42, N type power transistor 41 and controller 44.Described low voltage start circuit 40 is connected to voltage source V by inductor L1
INDescribed P type power transistor 42 comprises parasitic diode 43, and the one end is connected to the output V of described synchronous pressure-boosting converter
OUT, and described output V
OUTCan be used as the power supply input of the analog IC that comprises described low voltage start circuit 40 and oscillator 51.With regard to described parasitic diode 43, be chosen in 0.3 volt conducting voltage usually.One end LX of described N type power transistor 41 is connected in series to described P type power transistor 42, other end ground connection.One end of described controller 44 is electrically connected to described oscillator 51, it comprises delay cell 45 and logical block 46, wherein said logical block 46 is closed described N type power transistor 41 and is started described P type power transistor 42 when initial condition, and described delay cell 45 is closed described P type power transistor 42 after one period time of delay of initial condition, and allows described N type power transistor 41 operate as normal.
Fig. 5 (a) is the embodiment of the low voltage start circuit of synchronous pressure-boosting converter of the present invention, and Fig. 5 (b) is the sequential chart of Fig. 5 (a).The controller 44 of Fig. 4 can utilize counter 52 and a plurality of digital logic gate to be implemented.It is 2 that the counter 52 of present embodiment is selected count values, and changes its state when being transformed into high potential with the oscillator pulse wave by electronegative potential in the lump.When input voltage did not reach the starting resistor of oscillator, described oscillator 51 and described counter 52 were all exported electronegative potential, therefore can earlier described N type power transistor 41 be closed when initialization, more described P type power transistor 42 were started.By the conducting of described P type power transistor 42, voltage source V
INCan directly provide analog IC required supply voltage.For example work as voltage source V
INWhen being 0.9 volt, though experience the pressure drop of the drain-source level of described P type power transistor 42, output V
OUTStill can keep 0.75 volt voltage.Concerning many analog ICs, 0.75 volt supply voltage has been enough to make it to produce the oscillator pulse wave.Described counter 52 is connected to described oscillator 51, when described oscillator 51 through startup and after producing two pulse waves, the output B of described counter 52 is transformed into high potential with the oscillator pulse wave by electronegative potential.The potential state conversion of described counter 52 will cause closing earlier described P type power transistor 42, restart described N type power transistor 41.It should be noted that described inductor L1 is an energy-storage travelling wave tube, i.e. energy storage constantly before described counter 52 counts to 2 just passes the signal to output so that guarantee to supply after voltage has enough energy to make described oscillator 51 maintain stable running.In addition, voltage source V
INStill in continuous rising, even if therefore described P type power transistor 42 is closed, by the conducting of described parasitic diode 43 and the pressure drop (about 0.3 volt) of its generation of deduction, output V
OUTAfter through two pulse waves, still can keep 0.75 volt voltage, and be enough to continue to keep the running of described oscillator 51.
Method of the present invention is to described voltage source V in the input low-voltage
INAfter, start described oscillator 51 by described P type power transistor 42.Described oscillator 51 for example in one of oscillator 51 to four clocks, cuts out described P type power transistor 42 earlier after starting a period of time, restart described N type power transistor 41.Though described P type power transistor 42 has been closed, the guiding path of the parasitic diode 43 by described P type power transistor 42, described voltage source V
INStill can provide enough supply voltages so that 51 normal operations of described oscillator.And this moment voltage source V
INStill constantly rise, and the energy storage by described inductor L1, so can make whole analog IC normal operation.
The present invention does not need to use the Zener diode of routine techniques.Relatively, the present invention utilizes the parasitic diode 43 of P type power transistor 42 can reach purpose of the present invention, so the usable floor area of escapable cost of the present invention and reduction chip.In addition, the present invention utilizes the non-overlapping clock design of synchronous circuit, meets current designer trends.
Technology contents of the present invention and technical characterstic disclose as above, yet the those skilled in the art still may be based on teaching of the present invention and announcement and done all replacement and modifications that does not break away from spirit of the present invention.Therefore, protection scope of the present invention should be not limited to embodiment institute disclosure, and should comprise various do not break away from replacement of the present invention and modifications, and is contained by the claims of enclosing.
Claims (10)
1. the low voltage start circuit of a synchronous pressure-boosting converter, it is connected to voltage source by inductor, it is characterized in that described low voltage start circuit comprises:
P type power transistor, it comprises parasitic diode, and an end of described P type power transistor is connected to the power supply input of oscillator;
N type power transistor, an end of described N type power transistor is connected in series to the other end of described P type power transistor, the other end ground connection of described N type power transistor; And
Controller, it is electrically connected to described oscillator, described controller comprises delay cell and logical block, wherein said logical block is closed described N type power transistor and is started described P type power transistor when initial condition, and described delay cell is closed described P type power transistor and started described N type power transistor after one period time of delay of initial condition.
2. the low voltage start circuit of synchronous pressure-boosting converter according to claim 1 is characterized in that described delay cell comprises counter, and described counter is connected to the grid of described P type power transistor.
3. the low voltage start circuit of synchronous pressure-boosting converter according to claim 2 is characterized in that the output state conversion of described counter is transformed into high potential with described oscillator pulse wave by electronegative potential.
4. the low voltage start circuit of synchronous pressure-boosting converter according to claim 2 is characterized in that described counter is counting down to once change its state to four clocks.
5. the low voltage start circuit of a synchronous pressure-boosting converter, it is connected to voltage source by inductor, it is characterized in that described low voltage start circuit comprises:
P type power transistor, it comprises parasitic diode, and an end of described P type power transistor is connected to the power supply input of oscillator;
N type power transistor, an end of described N type power transistor is connected in series to the other end of described P type power transistor, the other end ground connection of described N type power transistor, wherein said P type power transistor and the not conducting simultaneously of described N type power transistor; And
Controller, it is electrically connected to described oscillator, and described controller starts described P type power transistor when initial condition, and makes the normal operation of described N type power transistor after one period time of delay of initial condition.
6. the low voltage start circuit of synchronous pressure-boosting converter according to claim 5 is characterized in that described controller comprises counter, and described counter is connected to the grid of described P type power transistor.
7. the low voltage start circuit of synchronous pressure-boosting converter according to claim 6 is characterized in that the output state conversion of described counter is transformed into high potential with the oscillator pulse wave by electronegative potential.
8. the low voltage start circuit of synchronous pressure-boosting converter according to claim 6 is characterized in that described counter is counting down to once change its state to four clocks.
9. the low-voltage startup method of a synchronous pressure-boosting converter is characterized in that comprising the following step:
The P type power transistor and the N type power transistor of polyphone are provided, the polyphone place of described P type power transistor and N type power transistor is connected to voltage source by inductor, and the other end of described P type power transistor is connected to the power supply input of oscillator, the other end ground connection of described N type power transistor;
Start voltage is hanged down in described voltage source output, and starts described oscillator by described P type power transistor; And
Described oscillator cuts out described P type power transistor after starting a period of time, and allows the normal operation of described N type power transistor.
10. the low-voltage startup method of synchronous pressure-boosting converter according to claim 9, it is characterized in that utilizing counter to calculate and close the time of described P type power transistor, and the conversion of the output state of described counter is transformed into high potential with the oscillator pulse wave by electronegative potential.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2007100904025A CN100521479C (en) | 2007-04-06 | 2007-04-06 | Low voltage start circuit for synchronous pressure-boosting converter and method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2007100904025A CN100521479C (en) | 2007-04-06 | 2007-04-06 | Low voltage start circuit for synchronous pressure-boosting converter and method thereof |
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| Publication Number | Publication Date |
|---|---|
| CN101282082A CN101282082A (en) | 2008-10-08 |
| CN100521479C true CN100521479C (en) | 2009-07-29 |
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| CNB2007100904025A Expired - Fee Related CN100521479C (en) | 2007-04-06 | 2007-04-06 | Low voltage start circuit for synchronous pressure-boosting converter and method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102297121B (en) * | 2011-05-11 | 2014-03-12 | 中达电子零组件(吴江)有限公司 | Detecting device and method of low-voltage start of fan |
| CN102497097A (en) * | 2011-12-08 | 2012-06-13 | 上海交通大学 | Ultra-low-voltage booster circuit for solar power generation |
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Granted publication date: 20090729 Termination date: 20170406 |