CN1430317A - Over-heat protective circuit - Google Patents
Over-heat protective circuit Download PDFInfo
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- CN1430317A CN1430317A CN 01138094 CN01138094A CN1430317A CN 1430317 A CN1430317 A CN 1430317A CN 01138094 CN01138094 CN 01138094 CN 01138094 A CN01138094 A CN 01138094A CN 1430317 A CN1430317 A CN 1430317A
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- resistance
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Abstract
An over-heat protector is composed of a temp detector for detecting the no-state voltage of power FET to obtain a temp signal proportional to current and outputting it to comparator, a current detector for detecting the drain current of Power FET to obtain a signal proportional to current and used as the reference of temp comparison, and a comparator for comparing the temp signal with the said reference for outputting protecting signal. Its advantage is no influence of load to over-heat protection.
Description
Technical field
The present invention relates to Switching Power Supply, be specifically related to the overheat protector of power field effect pipe.
Background technology
In the high-power low-voltage output module power supply, the power density of module is more and more higher in existing, and the thermal design of module becomes one of emphasis of modular design.In order to improve the reliability of module, middle high power module generally all has overheat protective function.In existing overtemperature protection scheme; mostly adopt thermistor or temperature switch as overheat detector spare; these devices all are to be placed near the thermals source such as power field effect pipe; sometimes because the needs of layout; overheat detector spare is distant from power field effect pipe; what therefore overheat detector spare detected is not the junction temperature of power device, but the mean temperature of module.The junction temperature of power device is high more a lot of than external temperature in fact, and what really should detect is the junction temperature of power field effect pipe, and above excess temperature detection means can't realize at all.
Because the conducting resistance R of power field effect pipe
Ds (on)Characteristic with positive temperature coefficient is so pass through the R of detection power field effect transistor
Ds (on)Just can obtain the junction temperature of power field effect pipe indirectly.Again because the forward conduction voltage drop U of power field effect pipe
DS (on)=R
Ds (on)* I
D, R wherein
Ds (on)Be the conducting resistance of power field effect pipe, I
DBe the drain current of power field effect pipe, so the forward conduction voltage drop U of detection power field effect transistor
DS (on)Just can detect R indirectly
Ds (on)But the forward conduction voltage drop U of verification and measurement ratio field effect transistor merely
DS (on)The problem that load effect overheat protector point can occur.Because when underloading, owing to flow through the electric current I of power field effect pipe
DVery little, even the junction temperature of power field effect pipe is very high, R
Ds (on)Very big, its conducting voltage is all very little, even that is to say when underloading the power field effect pipe excess temperature, depends merely on the conducting voltage U of detection power field effect transistor
DS (on)Can not make the thermal-shutdown circuit action of module, the overheat protector point during underloading will be very high like this, even can not realize overheat protector.
Summary of the invention
Technical problem to be solved by this invention is to overcome above-mentioned shortcoming, provide a kind of thermal-shutdown circuit of directly detection power field effect transistor junction temperature, and overheat protector point is not subjected to the influence of load variations.
The present invention includes: the temperature sensing circuit of power field effect pipe, current detection circuit, comparison circuit;
Temperature sensing circuit is used for the conducting voltage of detection power field effect transistor, obtains a temperature signal U who is directly proportional with electric current
DS (on), this signal is a potential pulse, and this signal is outputed to comparison circuit; U wherein
DS (on)=R
Ds (on)* I
D, R
Ds (on)Be the conducting resistance of power field effect pipe, I
DIt is the drain current of power field effect pipe;
Current detection circuit is used for the drain current of detection power field effect transistor, obtains a signal U who is directly proportional with electric current
REF, as temperature reference signal relatively, this signal is the potential pulse that is directly proportional with electric current, and this signal is outputed to comparison circuit; U wherein
REF=R
REF* I
D, R
REFBe the gain of current detection circuit, I
DIt is the drain current of power field effect pipe;
Comparison circuit, the temperature detection signal and the temperature reference signal that are used for being imported compare judgement, when temperature detection signal greater than the temperature reference signal time output overheat protector signal, this signal is used for blocking the gate drive signal DRIVE of power field effect pipe.
The present invention utilizes power field effect pipe conducting resistance R
Ds (on)This specific character of positive temperature coefficient, the forward conduction voltage drop U of detection power field effect transistor
DS (on)=R
Ds (on)* I
DDetect the electric current that flows through the power field effect pipe drain electrode simultaneously, obtain a temperature reference signal U who is directly proportional with electric current
REF=R
REF* I
DCompare U then
DS (on)And U
REF (on), be exactly in fact to compare conducting resistance R
Ds (on)With given resistance R
REF, eliminated the influence of load like this to overheat protector point, underloading will be very consistent with the overheat protector point of heavy duty.
Description of drawings
Fig. 1 is a theory diagram of the present invention.
Fig. 2 realizes physical circuit figure of the present invention.
Fig. 3 is the logic relation picture of each point in the embodiment of the invention.
Embodiment
The present invention is described in further detail below in conjunction with drawings and Examples:
Fig. 1 is a theory diagram of the present invention: comprising: temperature sensing circuit 101, current detection circuit 102, comparison circuit 103;
The conducting voltage of power field effect pipe Q1 is directly delivered to temperature sensing circuit 101, obtain a temperature signal U who is directly proportional with electric current by temperature sensing circuit
DS (on)=R
Ds (on)* I
D, this signal is a potential pulse;
The drain current of power field effect pipe Q1 is delivered to current detection circuit 102, obtain a signal U who is directly proportional with electric current by current detection circuit 102
REF=R
REF* I
D, as temperature reference signal relatively, this signal is the potential pulse that is directly proportional with electric current, wherein R
REFIt is the gain of current detection circuit;
Respectively temperature detection signal and the temperature reference signal of being imported compared judgement then, export an overheat protector signal at last, this signal is used for blocking the gate drive signal DRIVE of power field effect pipe.
Fig. 2 realizes physical circuit figure of the present invention.
Voltage reference Vref connects the anode of the first diode VD1, the 3rd diode VD3 and the 4th diode VD4 simultaneously through resistance R 1, resistance R 6 is connected across between the negative electrode and ground of the 4th diode VD4, the negative electrode of the first diode VD1 links to each other with drive signal Driver, has constituted temperature sensing circuit 101;
The first diode VD1 in the temperature sensing circuit 101, the negative electrode of the 3rd diode VD3 are received in the grid of power field effect pipe and drain electrode respectively; The former edge joint of current transformer T2 in the current detection circuit 102 is between the source electrode and ground of power field effect pipe Q1;
The negative electrode of the 4th diode VD4 of temperature sensing circuit 101 links to each other through the inverting input of resistance R 2 with comparator D1A;
The negative electrode of the second diode VD2 of current detection circuit 102 links to each other through the in-phase input end of resistance R 3 with comparator D1A;
The output output temperature protection signal of the comparator D1A of comparison circuit 103.
The work wave of each point is as shown in Figure 3 among Fig. 2: for convenience of description, suppose that the power field effect pipe junction temperature is normal in T1～T3 time, and T3～T5 time, power field effect pipe junction temperature excess temperature, it is normal that T5～T6 temporal power field effect transistor junction temperature is recovered.
Its operation principle is as follows:
In T1～T2 time, the A point is a high level, the Q1 conducting, and VD1 ends, the VD3 conducting, the current potential that B is ordered is the conduction voltage drop U of Q1
DS (on)=R
Ds (on)* I
D, the while obtains flowing through the drain current I of Q1 at the C point
DDetection signal U
REF=R5 * I
D/ N, at this moment U
DS (on)Waveform be the same with current detection signal, only amplitude is different; VD5 ends in addition, and voltage reference VREF can be not influential to the C point voltage.The comparator that constitutes by D1A obtains the impulse waveform that D is ordered subsequently.Because junction temperature is normal, so the current potential that D is ordered is a high level.In T2～T3 time, the current potential that A is ordered is 0, and Q1 ends, the VD1 conducting, and VD3 ends, because the effect of VD4 obtains 0 current potential at the B point, simultaneously, and the VD5 conducting, the C point has a very little direct voltage, and the D current potential of ordering still remains high level like this.
At T3 constantly, at this moment the junction temperature of Q1 rises a lot, under the identical situation of electric current, and U
DS (on)Increase thereupon, B point current potential rising like this, when the current potential of ordering as B is higher than the current potential that C orders, the current potential vanishing level that D is ordered.At T4 constantly, because the protective circuit action, power field effect pipe Q1 closes, so B point current potential becomes 0, C point current potential is a very little DC level again, and D point current potential becomes high level; When next switch periods begins, if Q1 excess temperature still can repeat the process of T3～T5.If the junction temperature of Q1 is normal, can allow the Q1 operate as normal, as T1～T3, T5～T6 time period.
Wherein, the 3rd diode VD3 should choose withstand voltage than higher diode, and its voltage withstand class is identical with power field effect pipe Q1; The first diode VD1, the 3rd diode VD3 and the 4th diode VD4 should choose the device of same model, help like this guaranteeing that overheat protector point as far as possible accurately;
The resistance of the choosing of the turn ratio N of current transformer T2, resistance R 5 is chosen the conducting resistance R with power field effect pipe
Ds (on)Relevant.If junction temperature is t1 during overheat protector, corresponding conducting resistance is R
Ds (on) (t1), then have following relation: R5/N=R
Ds (on) (t1)
Follow following principle during the choosing of the resistance of resistance R 8, resistance R 7 and power supply benchmark VREF in addition: when power field effect pipe Q1 conducting, the not influence of voltage that VREF is ordered to C; When Q1 ends, make the C point that a very little DC level be arranged.If choose rationally, can when load is very little, realize overheat protector, and overheat protector point and can be consistent when heavily loaded.
As seen from the above analysis; the present invention has realized the overheat protector of power field effect pipe really, and circuit is simple, and cost is lower than adding special-purpose temperature switch; the more important thing is the junction temperature protection that has realized power field effect pipe, more effectively protected power field effect pipe.The present invention is suitable for the occasion of all utilization power field effect pipes as main switch, can both use the overheat protector of the present invention as module in various circuit topologies, and protection is reliable, is the overheat protector of power field effect pipe truly.
Claims (6)
1, a kind of thermal-shutdown circuit comprises temperature sensing circuit (101), current detection circuit (102), comparison circuit (103); Described temperature sensing circuit (101) is used for the conducting voltage of detection power field effect transistor, obtains a temperature signal U who is directly proportional with electric current
DS (on), and this signal outputed to comparison circuit (103); U wherein
DS (on)=R
Ds (on)* I
D, R
Ds (on)Be the conducting resistance of power field effect pipe, I
DIt is the drain current of power field effect pipe;
Described current detection circuit (102) is used for the drain current of detection power field effect transistor, obtains a signal U who is directly proportional with electric current
REF,, and this signal outputed to comparison circuit as temperature reference signal relatively; U wherein
REF=R
REF* I
D, R
REFBe the gain of current detection circuit, I
DIt is the drain current of power field effect pipe;
Described comparison circuit (103), the temperature detection signal and the temperature reference signal that are used for being imported compare judgement, when temperature detection signal greater than the temperature reference signal time output overheat protector signal.
2, a kind of thermal-shutdown circuit according to claim 1; it is characterized in that described temperature sensing circuit (101) comprising: voltage reference Vref connects the anode of the first diode VD1, the 3rd diode VD3 and the 4th diode VD4 simultaneously through resistance R 1; resistance R 6 is connected across between the negative electrode and ground of the 4th diode VD4, and the negative electrode of the first diode VD1 links to each other with drive signal Driver.
3, a kind of thermal-shutdown circuit according to claim 1 and 2; it is characterized in that described current detection circuit (102) comprising: resistance R 4 is attempted by between the output and ground of current transformer T2; anode with the second diode VD2 is connected then, and resistance R 5 is connected across between the negative electrode and ground of the second diode VD2.
4, a kind of thermal-shutdown circuit according to claim 1 and 2, it is characterized in that described comparison circuit (103) comprising: resistance R 2 links to each other with the inverting input of comparator D1A; Voltage reference VREF links to each other with the anode of the 5th diode VD5 by resistance R 8, and resistance R 7 is connected across between this point and the ground; Resistance R 3 is connected across between the anode of the in-phase input end of D1A and the 5th diode VD5.
5, a kind of thermal-shutdown circuit according to claim 3, the resistance that it is characterized in that turn ratio N, the resistance R 5 of described current transformer T2 is chosen the conducting resistance R with power field effect pipe
Ds (on)Satisfy: R5/N=R
Ds (on) (t1), the junction temperature when wherein t1 is overheat protector, R
Ds (on) (t1)Conducting resistance for correspondence.
6, a kind of thermal-shutdown circuit according to claim 4, the resistance and the choosing of power supply benchmark VREF that it is characterized in that described resistance R 8, resistance R 7 be satisfied: when power field effect pipe Q1 conducting, make the input voltage not influence of VREF to resistance R 3; When Q1 ends, make the input point of resistance R 3 that a very little DC level be arranged.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB011380942A CN100416962C (en) | 2001-12-31 | 2001-12-31 | Over-heat protective circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB011380942A CN100416962C (en) | 2001-12-31 | 2001-12-31 | Over-heat protective circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1430317A true CN1430317A (en) | 2003-07-16 |
| CN100416962C CN100416962C (en) | 2008-09-03 |
Family
ID=4674381
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB011380942A Expired - Fee Related CN100416962C (en) | 2001-12-31 | 2001-12-31 | Over-heat protective circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100416962C (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100407572C (en) * | 2004-08-02 | 2008-07-30 | 阎跃军 | Field effect transistor biasing circuit |
| CN101192597B (en) * | 2007-03-15 | 2010-04-07 | 中兴通讯股份有限公司 | High low temperature protective circuit |
| CN102290995A (en) * | 2011-07-16 | 2011-12-21 | 西安电子科技大学 | Rectifier diode temperature compensation circuit in flyback converter |
| CN101826717B (en) * | 2009-10-23 | 2012-04-18 | 索凌电气有限公司 | Temperature measurement and protection control method |
| CN103675654A (en) * | 2012-09-06 | 2014-03-26 | 苏州工业园区新宏博通讯科技有限公司 | Temperature simulator |
| CN104362582A (en) * | 2014-10-31 | 2015-02-18 | 杭州华为企业通信技术有限公司 | Treatment method and device for preventing circuit board from being burnt |
| CN107732875A (en) * | 2016-08-12 | 2018-02-23 | 通用电气公司 | Solid circuit breaker and motor driven systems |
| CN111124002A (en) * | 2018-10-30 | 2020-05-08 | 宁波方太厨具有限公司 | Accurate temperature control method for household appliance |
| CN108124500B (en) * | 2015-09-23 | 2021-12-17 | 伊西康有限责任公司 | Surgical stapler with temperature-based motor control |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4896245A (en) * | 1989-03-13 | 1990-01-23 | Motorola Inc. | FET overtemperature protection circuit |
| JPH04340320A (en) * | 1991-05-13 | 1992-11-26 | Fujitsu General Ltd | Circuit protective device |
| US5737169A (en) * | 1996-02-28 | 1998-04-07 | Eni, A Division Of Astec America, Inc. | Intrinsic element sensing integrated SOA protection for power MOSFET switches |
-
2001
- 2001-12-31 CN CNB011380942A patent/CN100416962C/en not_active Expired - Fee Related
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100407572C (en) * | 2004-08-02 | 2008-07-30 | 阎跃军 | Field effect transistor biasing circuit |
| CN101192597B (en) * | 2007-03-15 | 2010-04-07 | 中兴通讯股份有限公司 | High low temperature protective circuit |
| CN101826717B (en) * | 2009-10-23 | 2012-04-18 | 索凌电气有限公司 | Temperature measurement and protection control method |
| CN102290995A (en) * | 2011-07-16 | 2011-12-21 | 西安电子科技大学 | Rectifier diode temperature compensation circuit in flyback converter |
| CN102290995B (en) * | 2011-07-16 | 2013-09-25 | 西安电子科技大学 | Rectifier diode temperature compensation circuit in flyback converter |
| CN103675654A (en) * | 2012-09-06 | 2014-03-26 | 苏州工业园区新宏博通讯科技有限公司 | Temperature simulator |
| CN104362582A (en) * | 2014-10-31 | 2015-02-18 | 杭州华为企业通信技术有限公司 | Treatment method and device for preventing circuit board from being burnt |
| CN108124500B (en) * | 2015-09-23 | 2021-12-17 | 伊西康有限责任公司 | Surgical stapler with temperature-based motor control |
| CN107732875A (en) * | 2016-08-12 | 2018-02-23 | 通用电气公司 | Solid circuit breaker and motor driven systems |
| US10591547B2 (en) | 2016-08-12 | 2020-03-17 | General Elecric Company | Solid state circuit breaker and motor driving system |
| CN111124002A (en) * | 2018-10-30 | 2020-05-08 | 宁波方太厨具有限公司 | Accurate temperature control method for household appliance |
| CN111124002B (en) * | 2018-10-30 | 2021-06-15 | 宁波方太厨具有限公司 | Accurate temperature control method for household appliance |
Also Published As
| Publication number | Publication date |
|---|---|
| CN100416962C (en) | 2008-09-03 |
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| C06 | Publication | ||
| PB01 | Publication | ||
| ASS | Succession or assignment of patent right |
Owner name: SHENZHENG CITY ZTE CO., LTD. Free format text: FORMER OWNER: SHENZHENG CITY ZTE CO., LTD. SHANGHAI SECOND INSTITUTE Effective date: 20030723 |
|
| C41 | Transfer of patent application or patent right or utility model | ||
| TA01 | Transfer of patent application right |
Effective date of registration: 20030723 Applicant after: Zhongxing Communication Co., Ltd., Shenzhen City Applicant before: Shanghai Inst. of No.2, Zhongxing Communication Co., Ltd., Shenzhen City |
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Granted publication date: 20080903 Termination date: 20171231 |
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| CF01 | Termination of patent right due to non-payment of annual fee |