CN1534853A - Error amplifier and direct current voltage conversion circuit and its method - Google Patents
Error amplifier and direct current voltage conversion circuit and its method Download PDFInfo
- Publication number
- CN1534853A CN1534853A CNA031212158A CN03121215A CN1534853A CN 1534853 A CN1534853 A CN 1534853A CN A031212158 A CNA031212158 A CN A031212158A CN 03121215 A CN03121215 A CN 03121215A CN 1534853 A CN1534853 A CN 1534853A
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- error amplifier
- voltage
- soft
- output
- start signal
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Abstract
An error amplifier, DC voltage converter, and their application method are disclosed. Said DC voltage converter can provide a soft starting function to the error amplifier. When the DC voltage converter is started, the output voltage of error amplifier will follow the slowly raising soft start voltage. When the soft start voltage is higher than the steady-state output voltage of error amplifier, the control of soft start voltage to error amplifier is lost and the error amplifier is controlled by input, so eliminating the dither of output voltage.
Description
Technical field
The present invention relates to a kind of error amplifier and DC voltage converting circuit (DC-DCconverter) and method thereof, particularly about a kind of error amplifier and DC voltage converting circuit and method thereof of utilizing soft start (soft start) with reduction voltage dithering (jitter).
Background technology
DC voltage converting circuit has been applied in the development and Design of electronic product widely.For portable product, when battery was in discharge condition, its output voltage values also descended thereupon.This moment is at the inner collocation one direct current voltage conversion circuit that needs of this portable product, in order to this output voltage is fixed in certain value.In addition, need many different operating voltages in the general electronic equipment usually, this function also needs to finish by DC voltage converting circuit.
Existing DC voltage converting circuit 10 as shown in Figure 1, comprises an error amplifier 11, a PWM comparator 12 and a driver 13.The output voltage V of this error amplifier 11
ErrBe magnification ratio (A
v) and reference voltage (V
Ref) deduction input voltage (IN or n
*V
Out) product.In order to prevent that output stage transistor from producing excessive immediate current when starting; when starting, this DC voltage converting circuit 10 can add a slow rising waveform at the input of this PWM comparator 12 as soft start; the output pulse width that makes this PWM comparator 12 becomes big gradually by little, with the immediate current that reduces output stage transistor and protect output stage transistor.
Fig. 2 (a) shows the time sequential routine figure of this existing DC voltage converting circuit 10 to 2 (c).In Fig. 2 (a), curve 22 is represented the input waveform (OSC) of this PWM comparator 12, and curve 21 is represented the slow rising waveform of soft start, and curve 23 is represented the output of this error amplifier 11.In Fig. 2 (b), the output pulse width of this PWM comparator 12 will present by little and become big trend gradually.In Fig. 2 (c), the output V of this DC voltage converting circuit 10
OutCurve 24 and present after input n
*V
OutCurve 25 will present slow rising, to reduce immediate current.
The shortcoming of existing DC voltage converting circuit 10 is the output waveform of uncontrollable this error amplifier 11 of soft start, so this error amplifier 11 will just be got back to steady state voltage after producing bigger instantaneous voltage, forms the state of a shake.For many electronic equipments, this shake will cause the puzzlement in the operation, and reduce reliability of products.
Because DC voltage converting circuit has belonged to the parts of a class necessity for many electronic equipments now, therefore how to reduce or eliminate the jitter phenomenon of its output voltage, be an important problem in fact.
Summary of the invention
Main purpose of the present invention provides a kind of error amplifier and DC voltage converting circuit and method thereof, and the voltage dithering phenomenon when its major function is to reduce power initiation is guaranteed the operate as normal and the product reliability of electronic equipment.
In order to achieve the above object, DC voltage converting circuit of the present invention is located at the function of soft start in one error amplifier.Because the adding of this soft start, when this DC voltage converting circuit starts, the output voltage of this error amplifier will be followed this soft start voltage that slowly rises.After soft start voltage surpassed the output voltage steady-state value of this error amplifier, this soft start was promptly out of hand to this error amplifier, and was controlled by the input of this error amplifier fully.Thus, just can eliminate or significantly reduce the jitter phenomenon of this error amplifier and this DC voltage converting circuit output voltage.
The error amplifier that the present invention discloses comprises a soft-start signal, an output signal, an input signal, a reference voltage, a clamp module and an error amplification module.This soft-start signal has the characteristic that rises gradually when electric power starting.This output signal will converge on a steady state voltage, and this input signal by this output signal through feed generation.When this soft-start signal during less than this steady state voltage, this clamp module is used for this output signal clamp to this soft-start signal.When this soft-start signal during greater than this steady state voltage, this error amplification module is used to amplify the difference that this reference voltage is deducted this input signal.
DC voltage converting circuit of the present invention comprises an error amplifier, a PWM comparator and a driver.One input of this PWM comparator is connected to this error amplifier, and another input is connected to a waveform.This driver is connected to this PWM comparator, is used to drive the electronic component of this DC voltage converting circuit outside.
DC voltage converting circuit method of the present invention comprises step (a) to (c).At step (a), a soft-start signal and a reference voltage that is connected to error amplifier is provided, this soft-start signal has the characteristic that rises gradually when this error amplifier starts, and the output of this error amplifier will converge on a steady state voltage.At step (b), when this soft-start signal during less than this steady state voltage, the output of this error amplifier will be by clamp to this soft-start signal.At step (c), when this soft-start signal during greater than this steady state voltage, the output of this error amplifier will be amplified the difference that this reference voltage is deducted the input signal of this error amplifier.
Error amplifier of the present invention and DC voltage converting circuit thereof have following advantage:
1. built-in soft start function.
2. can smoothly be risen and do not had the output voltage of shake.
3. can reduce the jitter phenomenon of changing voltage.
4. can directly control the Breadth Maximum of modulation pulse in the DC voltage converting circuit.
Description of drawings
The present invention will illustrate according to accompanying drawing, wherein:
Fig. 1 is existing DC voltage converting circuit;
Fig. 2 (a) is the sequential chart of existing DC voltage converting circuit to 2 (c);
Fig. 3 is an embodiment of DC voltage converting circuit of the present invention;
Fig. 4 is an embodiment of error amplifier of the present invention;
Fig. 5 is the sequential chart of error amplifier of the present invention;
Fig. 6 (a) to 6 (c) be the sequential chart of DC voltage converting circuit of the present invention; And
Fig. 7 is another embodiment of error amplifier of the present invention.
Element numbers explanation among the figure: 10 DC voltage converting circuit, 11 error amplifiers, the 12PWM comparator, 13 drivers, 21 soft start curves, 22 input waveforms, 23 curves of output, 24 curves of output, 25 input curves, 30 DC voltage converting circuit, 31 error amplifiers, the 32PWM comparator, 33 drivers, 34 soft activation, 35 voltage dividers, 41 first amplifying stages, 42 second amplifying stages, 43 clamp levels, 44 buffer stages, 45 first amplifiers, 46 the first transistors, 47 transistor secondses, 48 second amplifiers, 49 buffers, 61 soft start curves, 62 input waveforms, 63 curves of output, 64 curves of output, 65 input curves, 71 error amplifiers
Embodiment
Fig. 3 is an embodiment of DC voltage converting circuit of the present invention, and wherein this DC voltage converting circuit 30 comprises an error amplifier 31, a PWM comparator 32 and a driver 33.The output of this DC voltage converting circuit 30 is fed to input via a voltage divider 35, so the voltage ratio n of input and output is between 0 and 1.Be that with the difference of existing DC voltage converting circuit 10 maximums DC voltage converting circuit 30 of the present invention is located at the function of soft start 34 in the error amplifier 31.Because the adding of this soft start 34, when this DC voltage converting circuit 30 starts, the output voltage of this error amplifier 31 will be followed this soft start voltage that slowly rises.And as the steady-state value V of soft start voltage above the output voltage of this error amplifier 31
ErrAfter, this soft start 34 is promptly out of hand to this error amplifier 31, and is controlled by the input of this error amplifier 31 fully.Thus, can eliminate or significantly reduce the jitter phenomenon of this error amplifier 31 and these DC voltage converting circuit 30 output voltages.
Fig. 4 is an embodiment of the internal circuit configuration of error amplifier of the present invention.This error amplifier 31 comprises one first amplifying stage 41, one second amplifying stage 42, a clamp level (clampstage) 43 and a buffer stage 44.This first amplifying stage 41 comprises one first amplifier 45, is used to amplify the difference that this reference voltage Vref is deducted this input signal IN.This clamp level 43 comprises one second amplifier 48, is used to amplify the difference that these soft start 34 signals are deducted this output signal OUT.As this input signal IN during less than this reference voltage Vref, this clamp level 43 is used for this output signal OUT clamp to these soft start 34 signals.This buffer stage 44 comprises a buffer 49, is used to drive this output signal OUT.This second amplifying stage 42 comprises a first transistor 46 and the transistor seconds 47 by these clamp level 43 controls by these first amplifying stage, 41 controls, and the output of this first transistor 46 and transistor seconds 47 is electrically connected to this buffer stage 44.
Figure 5 shows that the time sequential routine figure of this error amplifier 31.Opening the beginning during state, soft start 34 slowly rises to V by 0
Cc, it starts this second amplifier 48 and transistor seconds 47 in the lump.This moment V
INLess than V
Ref, therefore first amplifier 45 is failure to actuate, and it exports V
O1Be 0, and cause the first transistor 46 of this second amplifying stage 42 to close.In other words, when initial state, this error amplifier 31 will be controlled by clamp level 43, second amplifier 42 and buffer stage 44, and the formation gain is 1 control loop.The output voltage of the buffer 49 of this buffer stage 44 will be followed the voltage of soft start 34, surpass the steady state voltage V of this error amplifier 31 up to the voltage of soft start 34
Err
When the voltage of soft start 34 surpasses steady state voltage V
ErrThe time, the output V of second amplifier 48 of this clamp level 43
O2Be 0, and transistor seconds 47 is closed.This moment, this error amplifier 31 was controlled by this first amplifying stage 41, second amplifying stage 42 and buffer stage 44, and output voltage is fixed in steady state voltage V
Err
Fig. 6 (a) is the time sequential routine figure of DC voltage converting circuit 30 of the present invention to 6 (c).In Fig. 6 (a), curve 62 is represented the input waveform (OSC) of this PWM comparator 32, and curve 61 is represented the slow rising waveform of soft start 34, and curve 63 is represented the output of this error amplifier 31.In Fig. 6 (b), the output pulse width of this PWM comparator 32 will present by little and become big trend gradually.In Fig. 6 (c), the output V of this DC voltage converting circuit 30
Out Curve 64 and present after input n
*V
OutCurve 65 will present slow rising, to reduce immediate current.The most important thing is that this DC voltage converting circuit 30 will directly converge to steady state voltage V
Err, can significantly reduce the shortcoming of voltage dithering in the prior art, guarantee the operate as normal and the product reliability of electronic equipment.
Fig. 7 is another embodiment of the internal circuit configuration of error amplifier 71 of the present invention.Different with the circuit structure of Fig. 4 is, an input of this second amplifier 48 is the input IN that are electrically connected to this error amplifier 71, but not output OUT.Yet as previously mentioned, the voltage of this input IN is to be produced through a voltage divider 35 by the voltage of this output OUT, and both have proportional relation.
Another characteristics of the present invention are to utilize the output pulse width of soft start 34 these PWM comparators 32 of control.If the ceiling voltage of soft start 34 is set in the V of the input waveform of this PWM comparator 32
hAnd V
lBetween, then the output voltage of this error amplifier 31 just can be followed the voltage of soft start 34 and is clamped on the maximum voltage place of this soft start 34, the so just output pulse width and the work period (duty cycle) of this PWM comparator 32 of may command.
Technology contents of the present invention and technical characterstic disclose as above, yet those skilled in the art may do all replacement and modifications that does not deviate from spirit of the present invention based on explanation of the present invention.Therefore, protection scope of the present invention should be not limited to the content that embodiment discloses, and should comprise various do not deviate from replacement of the present invention and modifications, and is contained by claims.
Claims (12)
1. error amplifier comprises:
One soft-start signal;
One input signal;
One reference voltage;
One output signal, it will converge on a steady state voltage;
One first amplifying stage is used to amplify the difference that described reference voltage is deducted described input signal;
One clamp level when described soft-start signal during less than described steady state voltage, is used for described output signal clamp to described soft-start signal;
One buffer stage is used to drive described output signal; And
One second amplifying stage comprises a first transistor and the transistor seconds by described clamp level control by described first amplifying stage control, and the output of described the first transistor and transistor seconds is electrically connected to described buffer stage.
2. error amplifier according to claim 1 is characterized in that described input signal is to produce through a voltage divider.
3. error amplifier according to claim 1 is characterized in that described clamp level is to utilize described input signal or output signal and described soft-start signal relatively.
4. error amplifier according to claim 1, it is characterized in that described the first transistor is activated during greater than described steady state voltage in described soft-start signal, and described transistor seconds is activated in described soft-start signal during less than described steady state voltage.
5. error amplifier comprises:
One soft-start signal, it has the characteristic that rises gradually when described error amplifier starts;
One output signal, it will converge on a steady state voltage;
One input signal;
One reference voltage;
One clamp module when described soft-start signal during less than described steady state voltage, is used for described output signal clamp to described soft-start signal; And
One error amplification module when described soft-start signal during greater than described steady state voltage, is used to amplify the difference that described reference voltage is deducted described input signal.
6. error amplifier according to claim 5 is characterized in that described clamp module is to utilize described input signal or output signal and described soft-start signal relatively.
7. error amplifier according to claim 5 is characterized in that described error amplifier comprises a buffer in addition, and the one end is connected to described clamp module and described error amplification module, and the other end is connected to described output signal.
8. error amplifier according to claim 5 is characterized in that described clamp module and error amplification module are to utilize one group of switching transistor output.
9. DC voltage converting circuit comprises:
One error amplifier as claimed in claim 5;
One PWM comparator, one input end is connected to described error amplifier, and another input is connected to a waveform; And
One driver is connected to described PWM comparator, is used to drive the electronic component of described DC voltage converting circuit outside.
10. DC voltage converting circuit according to claim 9, the output that it is characterized in that described error amplifier are between the high potential and electronegative potential of described waveform, thus the adjustment work period.
11. DC voltage converting circuit according to claim 9 is characterized in that the output of described driver is fed to the input of described error amplifier via a voltage divider.
12. a DC voltage transforming method comprises the following step;
One soft-start signal and the reference voltage that is connected to error amplifier is provided, and described soft-start signal has the characteristic that rises gradually when described error amplifier starts, and the output of described error amplifier will converge on a steady state voltage;
When described soft-start signal during less than described steady state voltage, the output of described error amplifier will be by clamp to described soft-start signal; And
When described soft-start signal during greater than described steady state voltage, the output of described error amplifier will be amplified the difference that described reference voltage is deducted the input signal of described error amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB031212158A CN1333512C (en) | 2003-03-28 | 2003-03-28 | Error amplifier and direct current voltage conversion circuit and its method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB031212158A CN1333512C (en) | 2003-03-28 | 2003-03-28 | Error amplifier and direct current voltage conversion circuit and its method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1534853A true CN1534853A (en) | 2004-10-06 |
| CN1333512C CN1333512C (en) | 2007-08-22 |
Family
ID=34285617
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB031212158A Expired - Fee Related CN1333512C (en) | 2003-03-28 | 2003-03-28 | Error amplifier and direct current voltage conversion circuit and its method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1333512C (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100409548C (en) * | 2006-05-31 | 2008-08-06 | 武汉大学 | Soft start/stop DC switch power supply and its controlling method |
| CN101841239A (en) * | 2010-04-12 | 2010-09-22 | 无锡中星微电子有限公司 | Boost DC/DC converter and logic control circuit thereof |
| CN101841240A (en) * | 2010-04-12 | 2010-09-22 | 无锡中星微电子有限公司 | Power supply converter and error amplifier |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1032719C (en) * | 1992-08-20 | 1996-09-04 | 北京铁路局计量管理所 | Logarithmic curve soft start circuit for switching power supply |
| US5917313A (en) * | 1997-12-19 | 1999-06-29 | Stmicroelectronics, Inc. | DC-to-DC converter with soft-start error amplifier and associated method |
| US6316926B1 (en) * | 2000-05-19 | 2001-11-13 | Stmicroelectronics S.R.L. | Switching control circuit |
-
2003
- 2003-03-28 CN CNB031212158A patent/CN1333512C/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100409548C (en) * | 2006-05-31 | 2008-08-06 | 武汉大学 | Soft start/stop DC switch power supply and its controlling method |
| CN101841239A (en) * | 2010-04-12 | 2010-09-22 | 无锡中星微电子有限公司 | Boost DC/DC converter and logic control circuit thereof |
| CN101841240A (en) * | 2010-04-12 | 2010-09-22 | 无锡中星微电子有限公司 | Power supply converter and error amplifier |
| WO2011127688A1 (en) * | 2010-04-12 | 2011-10-20 | 无锡中星微电子有限公司 | Power-switching device and error amplifier |
| CN101841239B (en) * | 2010-04-12 | 2012-07-04 | 无锡中星微电子有限公司 | Boost DC/DC converter and logic control circuit thereof |
| CN101841240B (en) * | 2010-04-12 | 2012-08-29 | 无锡中星微电子有限公司 | Power supply converter and error amplifier |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1333512C (en) | 2007-08-22 |
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Granted publication date: 20070822 |