CN101540497B - Thermal-shutdown circuit and method thereof - Google Patents

Thermal-shutdown circuit and method thereof Download PDF

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Publication number
CN101540497B
CN101540497B CN2008100827860A CN200810082786A CN101540497B CN 101540497 B CN101540497 B CN 101540497B CN 2008100827860 A CN2008100827860 A CN 2008100827860A CN 200810082786 A CN200810082786 A CN 200810082786A CN 101540497 B CN101540497 B CN 101540497B
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transistor
voltage
reinforced
temperature coefficient
npn
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CN101540497A (en
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简铭宏
陈家敏
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Holtek Semiconductor Inc
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Holtek Semiconductor Inc
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Abstract

The invention discloses a thermal-shutdown circuit, which is applied to an integrated circuit to control a power transistor of the integrated circuit, and comprises a temperature sensor and a comparator, wherein the temperature sensor is designed by matching the characteristics of the same tendency of a depletion type transistor (Depletion MOS) and an enhancement type transistor (Enhancement MOS) in technical variation, and is used for generating a positive temperature coefficient voltage and a negative temperature coefficient voltage, and the comparator is connected with the temperature sensor and used for comparing the positive temperature coefficient voltage and the negative temperature coefficient voltage to output an output voltage so as to control the on-off of the power transistor. Therefore, the thermal-shutdown circuit achieves the aims of reducing the using amount of the transistor to save the area occupied by the thermal-shutdown circuit in the integrated circuit and reduce the consumption of integral power.

Description

Thermal-shutdown circuit and method thereof
Technical field
The present invention relates to a kind of thermal-shutdown circuit, be meant a kind of thermal-shutdown circuit and method thereof that is applied in the integrated circuit especially.
Background technology
The part of the power management design in integrated circuit (IC) generally can design thermal-shutdown circuit, and whether purpose is to detect the integrated circuit internal temperature too high.Because when input voltage or output load current improperly produce, all might cause the IC interior temperature overheating and damage integrated circuit itself.At this moment,, will send a control signal and go to force the running of turning off integrated circuit, to reach the effect of protection integrated circuit itself and application circuit if thermal-shutdown circuit starts.
Please refer to Fig. 1, be applied to the synoptic diagram of the thermal-shutdown circuit of integrated circuit for prior art.This thermal-shutdown circuit is for example to be applied in the integrated circuit of a power management, and it comprises: a temperature sensor 90 and a comparer 91.Wherein, come temperature in the sensing integrated circuit by temperature sensor 90, to produce a negative temperature coefficient voltage V respectively NTCAn and positive temperature coefficient (PTC) voltage V PTC, and then utilize comparer 91 to receive negative temperature coefficient voltage and positive temperature coefficient (PTC) voltage, and compare to export an output voltage V OUTControl the power transistor in the integrated circuit of power management, to reach the protection of excess temperature.
Wherein, when design temperature sensor 90, tend to the temperature error of considering that non-ideal effects causes, wherein non-ideal effects comprise that assembly does not match in the circuit, the absolute value variation of technological parameter and operational amplifier or the offset voltage of comparer (Offset Voltage).And these non-ideal effects all have remarkable influence to the degree of accuracy of temperature sensor 90, so also just be enough to determine the whether accurate situation of running of thermal-shutdown circuit.And if will obtain the temperature sensor 90 of pinpoint accuracy, then most technology can be utilized analog-digital converter (as: Sigma-Delta ADC), with elder generation the error simulation conversion of signals is become digital signal, and then utilize the mode of digital signal processing to do from normal moveout correction.But, utilize digitized processing can allow temperature sensor 90 reach ± 0.1 ℃ pinpoint accuracy approximately really, but relative also just must taking sizable area and expend bigger power.
If but in the more not harsh application of the requirement of degree of accuracy (as the integrated circuit of power management), it is only to need to reduce non-ideal effects by circuit layout or circuit design skill., promptly be the framework that utilizes similar band gap (band-gap) circuit, also to allow positive temperature coefficient (PTC) voltage V just as the method for designing of the temperature sensor among Fig. 1 90 PTCCan be by the I in the circuit diagram PTAT *R2 tries to achieve; And negative temperature coefficient voltage V NTCThen be to provide, and then carry out the comparison of positive and negative temperature coefficient voltage and control power transistor in the integrated circuit of power management by institute after BJT transistor (Q3, the Q4) running.But, also just must use a large amount of transistors thus, except being increased in the puzzlement on the circuit design, equally also can take the area of bigger integrated circuit, and expend bigger power.
Therefore, how to design the few area with the reduction integrated circuit of number of transistors, and can reduce the thermal-shutdown circuit of the consume of power relatively, be to be worth the further place of research at present.
Summary of the invention
In view of this; technical matters to be solved by this invention is; a kind of thermal-shutdown circuit and method thereof are provided; in thermal-shutdown circuit; the characteristics of utilizing vague and general transistor npn npn (Depletion MOS) and reinforced transistor (Enhancement MOS) to have identical trend in the technology variation are designed to temperature sensor; be used for judging that with the control thermal-shutdown circuit excess temperature whether critical value can more accurately and not produce skew; and can reduce transistorized usage quantity and save thermal-shutdown circuit shared area in integrated circuit, and reduce expending of overall power.In addition, the present invention has also designed a magnetic hysteresis mechanism (Hysteresis Mechanism), with the output signal of avoiding thermal-shutdown circuit the repetitive operation that the height voltage level switches takes place under uniform temp.
In order to achieve the above object, the scheme according to proposed by the invention provides a kind of thermal-shutdown circuit, is applied to an integrated circuit, and to control a power transistor of this integrated circuit, these many temperature protection circuits comprise: a temperature sensor and a comparer.Wherein, temperature sensor is in order to produce positive temperature coefficient (PTC) voltage and a negative temperature coefficient voltage, and comparer connects this temperature sensor, is used for relatively this positive temperature coefficient (PTC) voltage and this negative temperature coefficient voltage and export an output voltage, to control the keying of this power transistor.In addition, this temperature sensor further comprises: one first circuit and a second circuit.Wherein, first circuit comprises one first vague and general transistor npn npn and one first reinforced transistor, to produce this positive temperature coefficient (PTC) voltage, and this first vague and general transistor npn npn is being connected of common gate end with this first reinforced transistor, this first vague and general transistor npn npn source terminal connects this first reinforced transistor drain end, and this first reinforced transistor source end ground connection.And this second circuit comprises one second vague and general transistor npn npn, one second reinforced transistor and one the 3rd reinforced transistor, to produce this negative temperature coefficient voltage, this second vague and general transistor npn npn is being connected of common gate end with this second reinforced transistor, this second vague and general transistor npn npn source terminal connects this second reinforced transistor drain end, and this second reinforced source transistor extremely connects the 3rd reinforced transistor drain end, the 3rd reinforced transistor source end ground connection.
In order to achieve the above object; according to another program proposed by the invention; a kind of over-temperature protection method is provided; be applied to an integrated circuit; keying in order to a power transistor of controlling this integrated circuit; its step comprises: at first; one temperature sensor is provided; to produce positive temperature coefficient (PTC) voltage and a negative temperature coefficient voltage; then, export the output voltage of a high voltage level and close this power transistor if this temperature sensor detects the internal temperature of this integrated circuit when being higher than a critical value.And then start a hysteresis circuit, and descend to allow this negative temperature coefficient voltage produce translation, and by the decline of the internal temperature of this integrated circuit, this positive temperature coefficient (PTC) voltage drop is low to moderate be able to the negative temperature coefficient voltage after descending with this translation to compare.At last, the output voltage of exporting a low-voltage position standard is opened this power transistor.
In order to achieve the above object; according to another scheme proposed by the invention; a kind of over-temperature protection method is provided; be applied to an integrated circuit; keying in order to a power transistor of controlling this integrated circuit; its step comprises: at first; one temperature sensor is provided; to produce positive temperature coefficient (PTC) voltage and a negative temperature coefficient voltage; then, export the output voltage of a high voltage level and close this power transistor if this temperature sensor detects the internal temperature of this integrated circuit when being higher than a critical value.And then start a hysteresis circuit, and rise to allow this positive temperature coefficient (PTC) voltage produce translation, and by the decline of the internal temperature of this integrated circuit, this negative temperature coefficient voltage is promoted to be able to the positive temperature coefficient (PTC) voltage after rising with this translation to compare.At last, the output voltage of exporting a low-voltage position standard is opened this power transistor.
By this, allow designed thermal-shutdown circuit that goes out and method under the situation of using less number of transistors, can also keep certain degree of accuracy, and be minimized the area of integrated circuit, and the consume that reduces overall power relatively.
Above general introduction and ensuing detailed description and accompanying drawing all are to reach mode, means and the effect that predetermined purpose is taked in order to further specify the present invention.And relevant other purpose of the present invention and advantage, will follow-up explanation and graphic in set forth.
Description of drawings
Fig. 1 is applied to the synoptic diagram of the thermal-shutdown circuit of integrated circuit for prior art;
Fig. 2 is the first embodiment circuit diagram of thermal-shutdown circuit of the present invention;
Fig. 3 is the synoptic diagram of thermal-shutdown circuit of the present invention to temperature variations;
Fig. 4 is the output voltage emulation synoptic diagram of thermal-shutdown circuit of the present invention when hysteresis circuit starts;
Fig. 5 is the second embodiment circuit diagram of thermal-shutdown circuit of the present invention;
Fig. 6 is the first embodiment process flow diagram of over-temperature protection method of the present invention;
Fig. 7 is the second embodiment process flow diagram of over-temperature protection method of the present invention; And
Fig. 8 is the synoptic diagram of the slope of different negative temperature coefficient voltages to temperature variations.
Wherein Reference numeral is:
Temperature sensor 90
Comparer 91
Amplifier OP
Positive temperature coefficient (PTC) voltage V PTC
Negative temperature coefficient voltage V NTC
Output voltage V OUT
BJT transistor Q3, Q4
Temperature sensor 11
First circuit 111
Second circuit 112
Comparer 12
Hysteresis circuit 13
The first vague and general transistor npn npn M DN1
The second vague and general transistor npn npn M DN2
The 3rd vague and general transistor npn npn M DN3
The first reinforced transistor M EN1
The second reinforced transistor M EN2
The 3rd reinforced transistor M EN3
The 4th reinforced transistor M EN4
Slender acanthopanax strong type transistor M EN5
Voltage source V DD
Gate terminal G
Drain electrode end D
Source terminal S
Positive temperature coefficient (PTC) voltage V PTC
Negative temperature coefficient voltage V NTC, V NTC1, V NTC2
Negative temperature coefficient voltage V after translation descends NTC.HYS
Output voltage V OUT
Embodiment
The present invention utilizes the characteristic of vague and general transistor npn npn (Depletion MOS) and reinforced transistor (Enhancement MOS) to design temperature sensor, and is applied in thermal-shutdown circuit.In addition, further in thermal-shutdown circuit, designed a magnetic hysteresis mechanism (HysteresisMechanism),, the accurate repetitive operation of switching in high and low position has taken place under uniform temp in order to avoid the output signal of thermal-shutdown circuit.So the present invention also just can use less transistor size, to reach the purpose that reduces area and power consumption.
Please refer to Fig. 2, be the first embodiment circuit diagram of thermal-shutdown circuit of the present invention.A kind of thermal-shutdown circuit that present embodiment provided; be applied to an integrated circuit (as: power management IC) (figure does not show); in order to the power transistor in the control integrated circuit (figure does not show); with when the internal temperature of integrated circuit is too high; thermal-shutdown circuit can start and close power transistor; forcing the running of ending integrated circuit, and then reach the effect of protection integrated circuit itself and application circuit.
The thermal-shutdown circuit of present embodiment comprises: a temperature sensor 11, a comparer 12 and a hysteresis circuit 13.Wherein, temperature sensor 11 is in order to produce a positive temperature coefficient (PTC) voltage V PTCAn and negative temperature coefficient voltage V NTC, and further comprise: one first circuit 111 and a second circuit 112.
The design of first circuit 111 comprises one first vague and general transistor npn npn M DN1And one first reinforced transistor M EN1, in order to produce this positive temperature coefficient (PTC) voltage V PTCWherein, the first vague and general transistor npn npn M DN1With the first reinforced transistor M EN1Be connection for common gate end (Gate), and the first vague and general transistor npn npn M DN1Source terminal (Source) connects the first reinforced transistor M EN1Drain electrode end (Drain), and the first reinforced transistor M EN1Source terminal ground connection.
The design of second circuit 112 then comprises one second vague and general transistor npn npn M DN2, one second reinforced transistor M EN2And one the 3rd reinforced transistor M EN3, in order to produce negative temperature coefficient voltage V NTCWherein, the second vague and general transistor npn npn M DN2With the second reinforced transistor M EN2Belong to the connection of common gate end, and the second vague and general transistor npn npn M DN2Source terminal connects the second reinforced transistor M EN2Drain electrode end, and the second reinforced transistor M EN2Source terminal further connects the 3rd reinforced transistor M EN3Drain electrode end, and the 3rd reinforced transistor M EN3Source terminal ground connection.
In addition, in the present embodiment, first circuit 111 and second circuit 112 are to carry out collocation design according to transistorized breadth length ratio (W/L) respectively, to produce this positive temperature coefficient (PTC) voltage V PTCAnd this negative temperature coefficient voltage V NTCAnd, the first vague and general transistor npn npn M wherein DN1, the second vague and general transistor npn npn M DN2, the first reinforced transistor M EN1, the second reinforced transistor M EN2And the 3rd reinforced transistor M EN3All be to adopt n channel metal oxide semiconductor field-effect transistor (N-Channel MOSFET) in design.
Then, can recognize in first circuit 111 and the second circuit 112 it is to arrange in pairs or groups by vague and general transistor npn npn and reinforced transistor respectively to connect design by the above, and refer again to the explanation of following formula about design concept wherein:
At first, if illustrate the voltage (V that it can produce with the temperature sensing circuit that a pair of vague and general transistor npn npn and reinforced transistor constituted TC) the mathematical notation formula be:
V TC = V TH . EN + ( W / L ) DN / ( W / L ) EN × V TH . DN
Wherein, V THENAnd V TH.DNThe conducting critical voltage of representing reinforced transistor and vague and general transistor npn npn respectively; And (W/L) ENAnd (W/L) DNThen be to represent employed reinforced transistor and the breadth length ratio of vague and general transistor npn npn on specification respectively.And then, calculate the voltage (V that is produced TC) temperature coefficient the time, then add temperature variations and calculate, can get following formula:
∂ V TC ∂ T = ∂ T TH . EN ∂ T + ( W / L ) DN / ( W / L ) EN × ∂ V TH . DN ∂ T
So, as the voltage (V that produces TC) temperature coefficient greater than zero the time, the expression voltage that temperature sensing circuit produced is positive temperature coefficient (PTC) voltage V PTCAnd if the voltage (V that produces TC) temperature coefficient less than zero the time, the voltage of then representing temperature sensing circuit and being produced is negative temperature coefficient voltage V NTCAnd in second circuit 112, promptly be to increase by the 3rd reinforced transistor M EN3Design make the voltage that second circuit 112 produced temperature coefficient less than zero, so second circuit 112 promptly is in order to produce negative temperature coefficient voltage V NTC
Moreover the comparer 12 in the present embodiment is to connect temperature sensor 11, wherein the positive temperature coefficient (PTC) voltage V that produced of first circuit 111 PTCBe a positive input (+) that is connected to comparer 12, and the negative temperature coefficient voltage V that second circuit 112 is produced NTCIt is a reverse input end (-) that is connected to comparer 12.Make that comparer 12 is in order to compare positive temperature coefficient (PTC) voltage V PTCAnd negative temperature coefficient voltage V NTCAnd export an output voltage V OUT, with the transistorized keying of power controlling.
And in design, comparer 12 is to compare positive temperature coefficient (PTC) voltage V PTCAnd negative temperature coefficient voltage V NTCAfterwards, further determine a critical value earlier, and then control this output voltage V of output based on this critical value OUTJust when the internal temperature of integrated circuit was higher than this critical value, comparer 12 was output voltage V of output one high voltage level OUT, to close power transistor; And when the internal temperature of integrated circuit was lower than this critical value, comparer 12 was output voltage V of output one low-voltage position standard OUT, to open power transistor.
Certainly, the power transistor in the present embodiment is for example to design with the P channel transistor, so the output voltage V of the height voltage level that comparer 12 is exported OUTBe to carry out the transistorized keying of power controlling smoothly.And the people who is familiar with this technology should understand the design that power transistor also can be the circuit of N channel transistor or other form, so comparer 12 just can be according to the difference of this power transistor, and designs different output voltage V thereupon OUTVoltage level come in response to demand for control, there is no at this and limited.
And when the design thermal-shutdown circuit, all must consider the temperature error that non-ideal effects caused, because these temperature errors will determine the degree of accuracy of thermal-shutdown circuit.So please also refer to Fig. 3, be the synoptic diagram of thermal-shutdown circuit of the present invention to temperature variations.As shown in FIG., as positive temperature coefficient (PTC) voltage V PTCAnd negative temperature coefficient voltage V NTCWhen being subjected to non-ideal effects and influencing, critical value T SHDNWill produce the temperature error of Δ t.
Yet, because the vague and general transistor npn npn and the reinforced transistorized technological parameter variation trend of institute of the present invention collocation design are identical, therefore at positive temperature coefficient (PTC) voltage V PTCAnd negative temperature coefficient voltage V NTCVariation will have equidirectional change.In other words, positive temperature coefficient (PTC) voltage V PTCAnd negative temperature coefficient voltage V NTCThe meeting while is translation Δ V up or down pWith Δ V n(as: the V shown in the figure PTC' and V NTC'), so when design, need only, adjust the temperature coefficient of needed positive and negative temperature coefficient voltage by selecting transistorized breadth length ratio, therefore the temperature error of critical value will dwindle.
Next, about the part of the hysteresis circuit 13 of present embodiment, its main purpose is to avoid the output signal of thermal-shutdown circuit, and the accurate repetitive operation of switching in height position takes place under uniform temp.Be design in design, be connected between the output terminal and second circuit 112 of comparer 12, and hysteresis circuit 13 itself is according to this output voltage V for a switch OUTCarry out open-close on-off, the negative temperature coefficient voltage V that is produced with further control second circuit 112 NTC
Hysteresis circuit 13 further comprises: one the 4th reinforced transistor M EN4An and slender acanthopanax strong type transistor M EN5The 4th reinforced transistor M wherein EN4Be to be connected to the second reinforced transistor M altogether EN2With the 3rd reinforced transistor M EN3Contact, and the 4th reinforced transistor M EN4Source terminal is a ground connection.And slender acanthopanax strong type transistor M EN5Gate terminal is the output terminal that connects comparer 12, and slender acanthopanax strong type transistor M EN5Source terminal is to connect the 4th reinforced transistor M EN4Drain electrode end is by this to form hysteresis circuit 13.In addition, because slender acanthopanax strong type transistor M EN5Operate in three and draw the district, therefore can be considered as so-called switch designs.
So when the internal temperature of integrated circuit was higher than critical value, thermal-shutdown circuit can start, just comparer 12 is output voltage V of meeting output HIGH voltage position standard OUT, this moment slender acanthopanax strong type transistor M EN5The meeting conducting makes hysteresis circuit 13 start; Otherwise if the internal temperature of integrated circuit is in critical value the time, then thermal-shutdown circuit can not start, and 12 of comparers are the output voltage V of output LOW voltage position standard OUT, this moment slender acanthopanax strong type transistor M EN5Can conducting, making hysteresis circuit 13 is to be in closed condition.
To this, please, be the output voltage emulation synoptic diagram of thermal-shutdown circuit of the present invention when hysteresis circuit starts again simultaneously with reference to figure 4.As shown in the figure, the internal temperature when integrated circuit is increased to gradually above critical value T SHDNThe time, thermal-shutdown circuit can start, and also just shown in the path of curve among the figure 1, comparer 12 is output voltage V of output HIGH voltage position standard immediately OUT, make when hysteresis circuit 13 also starts, can control second circuit 112 and allow negative temperature coefficient voltage V NTCThe generation translation descends, the negative temperature coefficient voltage V of the decline of the translation shown in the figure just back NTC.HYSSo, when the internal temperature of integrated circuit begins to descend because of the startup of thermal-shutdown circuit, positive temperature coefficient (PTC) voltage V PTCAlso can reduce the negative temperature coefficient voltage V after descending with temperature with translation NTC.HYSWhen being able to compare by comparer 12, promptly can be shown in the path of curve among the figure 2, comparer 12 recovers to become the output voltage V of output LOW voltage position standard OUT
And the zone (T that is surrounded by curve 1 and curve 2 among Fig. 4 HYS) can be described as temperature magnetic hysteresis window (Temperature Hysteresis Windows).And the practice of the magnetic hysteresis mechanism of present embodiment can make the magnetic hysteresis window comparatively fixing, because the size of magnetic hysteresis window is by the 3rd reinforced transistor M EN3And the 4th reinforced transistor M EN4The dimension scale specification determine.So as the second vague and general transistor npn npn M DN2Electric current when changed by non-ideal effects, the 3rd reinforced transistor M that matches each other EN3And the 4th reinforced transistor M EN4Can allow the magnetic hysteresis window unaffected.
Refer again to Fig. 5, be the second embodiment circuit diagram of thermal-shutdown circuit of the present invention.Present embodiment is identical with the first embodiment circuit diagram in the design of temperature sensor 11 and comparer 12, and with the first embodiment circuit diagram maximum be not both the design that is hysteresis circuit 13.The hysteresis circuit 13 of present embodiment is to be connected between the output terminal and first circuit 111 of comparer 12, is used for controlling the positive temperature coefficient (PTC) voltage V that lifting first circuit 111 is produced PTCAnd by positive temperature coefficient (PTC) voltage V PTCLifting also can reach the magnetic hysteresis effect identical with the first embodiment circuit diagram.
As shown in Figure 5, the hysteresis circuit 13 of present embodiment comprises: one the 3rd vague and general transistor npn npn M DN3And one the 4th vague and general transistor npn npn M EN4Wherein, the 3rd vague and general transistor npn npn M DN3Gate terminal is directly to connect the 3rd vague and general transistor npn npn M DN3Source terminal, and the 3rd vague and general transistor npn npn M DN3Drain electrode end connects voltage source V DDAnd the 4th reinforced transistor M EN4Gate terminal is the output terminal that connects comparer 12, and the 4th reinforced transistor M EN4Source terminal is connected in the first reinforced transistor M EN1Gate terminal, and the 4th reinforced transistor M EN4Drain electrode end connects the 3rd vague and general transistor npn npn M DN3Source terminal.
So, can provide a similar charge path to promote the positive temperature coefficient (PTC) voltage V that first circuit 111 is produced by the design of this hysteresis circuit 13 PTCAnd that is to say with regard to whole thermal-shutdown circuit, when over-temperature protection does not start, the 4th reinforced transistor M EN4Can't conducting, so hysteresis circuit 13 just can not start yet; And when over-temperature protection starts, the output voltage V of comparer 12 output HIGH voltage position standards OUT, this moment the 4th reinforced transistor M EN4Also will conducting, and by the 3rd vague and general transistor npn npn M DN3And the 4th reinforced transistor M EN4Form charge path, make the circuit 111 positive temperature coefficient (PTC) voltage V that produces that wins PTCPromote, and finish the effect of magnetic hysteresis.
Following the explanation of following two flow implementation examples, is in order to further specify actual operation flow process of the present invention.Fig. 6 is the first embodiment process flow diagram of over-temperature protection method of the present invention.As shown in the figure, present embodiment provides a kind of over-temperature protection method, and it is to be applied to an integrated circuit equally, in order to the keying of the power transistor of control integrated circuit.The step of over-temperature protection method comprises: at first, provide a temperature sensor 11 (S601), and produce a positive temperature coefficient (PTC) voltage V in order to design PTCAn and negative temperature coefficient voltage V NTC, then, whether the internal temperature that detects integrated circuit is higher than a critical value (S603).
If the testing result of step (S603) is that the internal temperature of then representing integrated circuit is not in normal range, and thermal-shutdown circuit need not start, and continues the output voltage V of output one low-voltage position standard OUT, continue running to open power transistor, and proceed to detect the internal temperature of integrated circuit.Otherwise, too high and must the startup thermal-shutdown circuit if the testing result of step (S603), is then represented temperature for being, so export the output voltage V of a high voltage level OUTClose power transistor (S605), cause damage to avoid integrated circuit to continue running.
And then, start a hysteresis circuit 13, to allow negative temperature coefficient voltage V NTCProduce translation and descend (S607), and because power transistor has been closed in the startup of thermal-shutdown circuit, so just can reduce the internal temperature (S609) of integrated circuit.And and then, just judge positive temperature coefficient (PTC) voltage V PTCWhether be reduced to negative temperature coefficient voltage V after being able to descend with this translation because of the internal temperature of integrated circuit NTC.HYSCompare (S611).If judged result is for being then to recover the output voltage V of output LOW voltage position standard OUT, to open power transistor (S613).Opposite, if the judged result of step (S611) is then represented positive temperature coefficient (PTC) voltage V for not PTCBe not reduced to the voltage of specific temperature spot as yet, thereby the negative temperature coefficient voltage V after failing to descend with this translation NTC.HYSCompare, then the step of being repeated to (S609), to continue to reduce the internal temperature of integrated circuit.
By this,, can reach the running of present embodiment over-temperature protection method, and allow integrated circuit when the excess temperature situation produces, have over-temperature protection and the effect of closing, and after the releasing of excess temperature situation, resume operation automatically by repeating above-mentioned steps.
Fig. 7 is the second embodiment process flow diagram of over-temperature protection method of the present invention.As shown in the figure, present embodiment is roughly identical with the first embodiment process flow diagram, and maximum difference is the difference that the running of hysteresis circuit 13 designs, and present embodiment is at positive temperature coefficient (PTC) voltage V PTCDo the adjustment that translation is risen, and first embodiment is at negative temperature coefficient voltage V NTCDo the adjustment that translation descends.
And detailed process is described as follows: at first, provide a temperature sensor 11 (S701), and produce a positive temperature coefficient (PTC) voltage V in order to design PTCAn and negative temperature coefficient voltage V NTC, then, whether the internal temperature that detects integrated circuit is higher than a critical value (S703).
If the testing result of step (S703) is that the internal temperature of then representing integrated circuit is not in normal range, and thermal-shutdown circuit need not start, and continues the output voltage V of output one low-voltage position standard OUT, continue running to open power transistor, and proceed to detect the internal temperature of integrated circuit.Otherwise, too high and must the startup thermal-shutdown circuit if the testing result of step (S703), is then represented temperature for being, so export the output voltage V of a high voltage level OUTClose power transistor (S705), cause damage to avoid integrated circuit to continue running.
And then, start hysteresis circuit 13, to allow positive temperature coefficient (PTC) voltage V PTCProduce translation and rise (S707), and because power transistor has been closed in the startup of thermal-shutdown circuit, so just can reduce the internal temperature (S709) of integrated circuit.And and then, just judge negative temperature coefficient voltage V NTCWhether compare (S711) because of the internal temperature of the integrated circuit positive temperature coefficient (PTC) voltage that is promoted to after being able to rise that descends with this translation.If judged result is for being then to recover the output voltage V of output LOW voltage position standard OUT, to open power transistor (S713), the running that recovers integrated circuit.Opposite, if the judged result of step (S711) is then represented negative temperature coefficient voltage V for not NTCDo not rise to the voltage of specific temperature spot as yet, thereby the positive temperature coefficient (PTC) voltage after failing to rise with this translation compares, then the step of being repeated to (S709), to continue to reduce the internal temperature of integrated circuit.At last, by repeating above-mentioned steps, can reach the running of present embodiment over-temperature protection method.
Subsidiary one carry be, in the solution of the temperature error that aforementioned reduction non-ideal effects is caused, more can be further by increasing positive temperature coefficient (PTC) voltage V PTCOr negative temperature coefficient voltage V NTCSlope reach and dwindle the error that non-ideal effects causes temperature.As shown in Figure 8, be the synoptic diagram of the slope of different negative temperature coefficient voltages to temperature variations.As we can see from the figure, as positive temperature coefficient (PTC) voltage V PTCBe subjected to the influence of non-ideal effects, make positive temperature coefficient (PTC) voltage V PTCTranslation Δ V makes progress pAnd become V PTC 'And different negative temperature coefficient voltage V NTC1And V NTC2(V NTC1Slope is greater than V NTC2Slope) will have different temperature error results, wherein, negative temperature coefficient voltage V NTC1The temperature error Δ t1 that produces will be less than negative temperature coefficient voltage V NTC2The temperature error Δ t2 that is produced.
In sum; thermal-shutdown circuit of the present invention; be that the characteristics of utilizing vague and general transistor npn npn and reinforced transistor to have identical trend in the technology variation are designed to temperature sensor; be used for judging that with the control thermal-shutdown circuit excess temperature whether critical value can more accurately and not produce skew; and and then transistorized usage quantity can be reduced and save thermal-shutdown circuit shared area in integrated circuit, and reduce expending of overall power.In addition, more design has the mechanism of hysteresis circuit, with the output signal of avoiding thermal-shutdown circuit the repetitive operation that the height voltage level switches takes place under uniform temp.
Though the present invention discloses as above with preferred embodiment; right its is not in order to limit the present invention; under the situation that does not deviate from spirit of the present invention and essence thereof; those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection domain of the appended claim of the present invention.

Claims (20)

1. a thermal-shutdown circuit is characterized in that, is applied to an integrated circuit, and in order to control a power transistor of this integrated circuit, this thermal-shutdown circuit comprises:
One temperature sensor, in order to producing positive temperature coefficient (PTC) voltage and a negative temperature coefficient voltage, and this temperature sensor further comprises:
One first circuit, comprise one first vague and general transistor npn npn and one first reinforced transistor, in order to produce this positive temperature coefficient (PTC) voltage, wherein this first vague and general transistor npn npn is being connected of common gate end with this first reinforced transistor, and this first vague and general transistor npn npn source terminal connects this first reinforced transistor drain end, and this first reinforced transistor source end ground connection; And
One second circuit, comprise one second vague and general transistor npn npn, one second reinforced transistor and one the 3rd reinforced transistor, in order to produce this negative temperature coefficient voltage, wherein this second vague and general transistor npn npn is being connected of common gate end with this second reinforced transistor, and this second vague and general transistor npn npn source terminal connects this second reinforced transistor drain end, and this second reinforced source transistor extremely connects the 3rd reinforced transistor drain end, and the 3rd reinforced transistor source end ground connection;
One comparer connects this temperature sensor, is used for relatively that this positive temperature coefficient (PTC) voltage and this negative temperature coefficient voltage decide a critical value, and then exports an output voltage based on this critical value, to control the keying of this power transistor; When the internal temperature of this integrated circuit is higher than this critical value, this comparer is exported the output voltage of a high voltage level, to close this power transistor, and when if the internal temperature of this integrated circuit is lower than this critical value, this comparer is exported the output voltage of a low-voltage position standard, to open this power transistor; And
One hysteresis circuit is the design of a switch, is connected in an output terminal and this second circuit of this comparer, in order to carry out open-close on-off according to this output voltage, to control this negative temperature coefficient voltage that this second circuit is produced;
By this, when this comparer is exported the output voltage of this high voltage level, this hysteresis circuit can start, descend to allow this negative temperature coefficient voltage produce translation, and descend at the internal temperature of this positive temperature coefficient (PTC) voltage along with this integrated circuit, and being reduced to negative temperature coefficient voltage after descending with this translation when being able to compare by this comparer, this comparer reverts to the output voltage of this low-voltage position standard of output.
2. thermal-shutdown circuit as claimed in claim 1; it is characterized in that; this positive temperature coefficient (PTC) voltage that described first circuit is produced provides the positive input to this comparer, and this negative temperature coefficient voltage that this second circuit produced provides the reverse input end to this comparer.
3. thermal-shutdown circuit as claimed in claim 1 is characterized in that, described first circuit and this second circuit carry out collocation design according to transistorized breadth length ratio respectively, to produce this positive temperature coefficient (PTC) voltage and this negative temperature coefficient voltage.
4. thermal-shutdown circuit as claimed in claim 1; it is characterized in that the described first vague and general transistor npn npn, this second vague and general transistor npn npn, this first reinforced transistor, this second reinforced transistor and the 3rd reinforced transistor are the designs of adopting the n channel metal oxide semiconductor field-effect transistor.
5. thermal-shutdown circuit as claimed in claim 1 is characterized in that, this hysteresis circuit comprises:
One the 4th reinforced transistor, the 4th reinforced transistor gate are connected to this second reinforced transistor AND gate the 3rd reinforced transistorized contact extremely altogether, and the 4th reinforced source transistor extremely is a ground connection; And
One slender acanthopanax strong type transistor, this slender acanthopanax strong type transistor gate extremely connects the output terminal of this comparer, and this slender acanthopanax strong type source transistor extremely connects the 4th reinforced transistor drain end.
6. a thermal-shutdown circuit is characterized in that, is applied to an integrated circuit, and in order to control a power transistor of this integrated circuit, this thermal-shutdown circuit comprises:
One temperature sensor, in order to producing positive temperature coefficient (PTC) voltage and a negative temperature coefficient voltage, and this temperature sensor further comprises:
One first circuit, comprise one first vague and general transistor npn npn and one first reinforced transistor, in order to produce this positive temperature coefficient (PTC) voltage, wherein this first vague and general transistor npn npn is being connected of common gate end with this first reinforced transistor, and this first vague and general transistor npn npn source terminal connects this first reinforced transistor drain end, and this first reinforced transistor source end ground connection; And
One second circuit, comprise one second vague and general transistor npn npn, one second reinforced transistor and one the 3rd reinforced transistor, in order to produce this negative temperature coefficient voltage, wherein this second vague and general transistor npn npn is being connected of common gate end with this second reinforced transistor, and this second vague and general transistor npn npn source terminal connects this second reinforced transistor drain end, and this second reinforced source transistor extremely connects the 3rd reinforced transistor drain end, and the 3rd reinforced transistor source end ground connection;
One comparer connects this temperature sensor, is used for relatively that this positive temperature coefficient (PTC) voltage and this negative temperature coefficient voltage decide a critical value, and then exports an output voltage based on this critical value, to control the keying of this power transistor; When the internal temperature of this integrated circuit is higher than this critical value, this comparer is exported the output voltage of a high voltage level, to close this power transistor, and when if the internal temperature of this integrated circuit is lower than this critical value, this comparer is exported the output voltage of a low-voltage position standard, to open this power transistor; And
One hysteresis circuit; Be the design of a switch, be connected in an output terminal and this first circuit of this comparer, in order to carry out open-close on-off, to control this positive temperature coefficient (PTC) voltage that this first circuit is produced according to this output voltage;
By this, when this comparer system exports the output voltage of this high voltage level, this hysteresis circuit can start, rise to allow this positive temperature coefficient (PTC) voltage produce translation, and descend at the internal temperature of this negative temperature coefficient voltage along with this integrated circuit, and when rising to positive temperature coefficient (PTC) voltage after rising with this translation and being able to be compared by this comparer, this comparer reverts to the output voltage of this low-voltage position standard of output.
7. thermal-shutdown circuit as claimed in claim 6; it is characterized in that; this positive temperature coefficient (PTC) voltage that described first circuit is produced provides the positive input to this comparer, and this negative temperature coefficient voltage that this second circuit produced provides the reverse input end to this comparer.
8. thermal-shutdown circuit as claimed in claim 6 is characterized in that, described first circuit and this second circuit carry out collocation design according to transistorized breadth length ratio respectively, to produce this positive temperature coefficient (PTC) voltage and this negative temperature coefficient voltage.
9. thermal-shutdown circuit as claimed in claim 6; it is characterized in that the described first vague and general transistor npn npn, this second vague and general transistor npn npn, this first reinforced transistor, this second reinforced transistor and the 3rd reinforced transistor are the designs of adopting the n channel metal oxide semiconductor field-effect transistor.
10. thermal-shutdown circuit as claimed in claim 6 is characterized in that, this hysteresis circuit comprises:
One the 3rd vague and general transistor npn npn, the 3rd vague and general transistor npn npn gate terminal is connected with the 3rd vague and general transistor npn npn source terminal, and the 3rd vague and general transistor npn npn drain electrode end connects a voltage source; And
One the 4th reinforced transistor, the 4th reinforced transistor gate extremely connects the output terminal of this comparer, and it is extreme that the 4th reinforced source transistor extremely is connected in this first reinforced transistor gate, and the 4th reinforced transistor drain end connects the 3rd vague and general transistor npn npn source terminal.
11. an over-temperature protection method is characterized in that, is applied to an integrated circuit, in order to the keying of a power transistor of controlling this integrated circuit, its step comprises:
One temperature sensor is provided, to produce positive temperature coefficient (PTC) voltage and a negative temperature coefficient voltage, and this temperature sensor further comprises: one first circuit, comprise one first vague and general transistor npn npn and one first reinforced transistor, in order to produce this positive temperature coefficient (PTC) voltage, wherein this first vague and general transistor npn npn is being connected of common gate end with this first reinforced transistor, and this first vague and general transistor npn npn source terminal connects this first reinforced transistor drain end, and this first reinforced transistor source end ground connection; An and second circuit, comprise one second vague and general transistor npn npn, one second reinforced transistor and one the 3rd reinforced transistor, in order to produce this negative temperature coefficient voltage, wherein this second vague and general transistor npn npn is being connected of common gate end with this second reinforced transistor, and this second vague and general transistor npn npn source terminal connects this second reinforced transistor drain end, and this second reinforced source transistor extremely connects the 3rd reinforced transistor drain end, and the 3rd reinforced transistor source end ground connection;
If when the internal temperature that this temperature sensor detects this integrated circuit is higher than a critical value, exports the output voltage of a high voltage level and close this power transistor;
Start a hysteresis circuit, descend to allow this negative temperature coefficient voltage produce translation;
By the decline of the internal temperature of this integrated circuit, reduce the negative temperature coefficient voltage of this positive temperature coefficient (PTC) voltage after be able to descend and compare with this translation; And
Export the output voltage of a low-voltage position standard and open this power transistor.
12. over-temperature protection method as claimed in claim 11; it is characterized in that; described temperature sensor utilizes the one first reinforced transistorized design of arranging in pairs or groups of one first vague and general transistor npn npn to produce this positive temperature coefficient (PTC) voltage, and utilizes arrange in pairs or groups one second reinforced transistor and one the 3rd reinforced transistorized design of one second vague and general transistor npn npn to produce this negative temperature coefficient voltage.
13. over-temperature protection method as claimed in claim 12 is characterized in that, described temperature sensor carries out collocation design according to transistorized breadth length ratio, to produce this positive temperature coefficient (PTC) voltage and this negative temperature coefficient voltage respectively.
14. over-temperature protection method as claimed in claim 12; it is characterized in that the described first vague and general transistor npn npn, this second vague and general transistor npn npn, this first reinforced transistor, this second reinforced transistor and the 3rd reinforced transistor adopt the design of n channel metal oxide semiconductor field-effect transistor.
15. over-temperature protection method as claimed in claim 11 is characterized in that, described critical value is by relatively this positive temperature coefficient (PTC) voltage and this negative temperature coefficient voltage form.
16. an over-temperature protection method is characterized in that, is applied to an integrated circuit, in order to the keying of a power transistor of controlling this integrated circuit, its step comprises:
One temperature sensor is provided, to produce positive temperature coefficient (PTC) voltage and a negative temperature coefficient voltage, and this temperature sensor further comprises: one first circuit, comprise one first vague and general transistor npn npn and one first reinforced transistor, in order to produce this positive temperature coefficient (PTC) voltage, wherein this first vague and general transistor npn npn is being connected of common gate end with this first reinforced transistor, and this first vague and general transistor npn npn source terminal connects this first reinforced transistor drain end, and this first reinforced transistor source end ground connection; An and second circuit, comprise one second vague and general transistor npn npn, one second reinforced transistor and one the 3rd reinforced transistor, in order to produce this negative temperature coefficient voltage, wherein this second vague and general transistor npn npn is being connected of common gate end with this second reinforced transistor, and this second vague and general transistor npn npn source terminal connects this second reinforced transistor drain end, and this second reinforced source transistor extremely connects the 3rd reinforced transistor drain end, and the 3rd reinforced transistor source end ground connection;
If when the internal temperature that this temperature sensor detects this integrated circuit is higher than a critical value, exports the output voltage of a high voltage level and close this power transistor;
Start a hysteresis circuit, rise to allow this positive temperature coefficient (PTC) voltage produce translation;
By the decline of the internal temperature of this integrated circuit, promote the positive temperature coefficient (PTC) voltage of this negative temperature coefficient voltage after be able to rise and compare with this translation; And
Export the output voltage of a low-voltage position standard and open this power transistor.
17. over-temperature protection method as claimed in claim 16; it is characterized in that; described temperature sensor utilizes the one first reinforced transistorized design of arranging in pairs or groups of one first vague and general transistor npn npn to produce this positive temperature coefficient (PTC) voltage, and utilizes arrange in pairs or groups one second reinforced transistor and one the 3rd reinforced transistorized design of one second vague and general transistor npn npn to produce this negative temperature coefficient voltage.
18. over-temperature protection method as claimed in claim 17 is characterized in that, described temperature sensor is to carry out collocation design according to transistorized breadth length ratio, to produce this positive temperature coefficient (PTC) voltage and this negative temperature coefficient voltage respectively.
19. over-temperature protection method as claimed in claim 17; it is characterized in that the described first vague and general transistor npn npn, this second vague and general transistor npn npn, this first reinforced transistor, this second reinforced transistor and the 3rd reinforced transistor adopt the design of n channel metal oxide semiconductor field-effect transistor.
20. over-temperature protection method as claimed in claim 16 is characterized in that, described critical value is by relatively this positive temperature coefficient (PTC) voltage and this negative temperature coefficient voltage form.
CN2008100827860A 2008-03-19 2008-03-19 Thermal-shutdown circuit and method thereof Expired - Fee Related CN101540497B (en)

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CN102013669B (en) * 2010-11-16 2013-09-18 中国电子科技集团公司第五十八研究所 Adjustable overheat protection circuit in switching power supply
TWI521819B (en) * 2013-09-24 2016-02-11 新唐科技股份有限公司 Integrated circuit and operation system with protection function
CN108988292A (en) * 2018-07-27 2018-12-11 南昌黑鲨科技有限公司 Thermal-shutdown circuit and data line with it
JP6477964B1 (en) * 2018-09-13 2019-03-06 ミツミ電機株式会社 Secondary battery protection circuit
CN114123105B (en) * 2021-11-19 2023-07-04 深圳市迪浦电子有限公司 Over-temperature protection circuit and method for power management LDO system

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