CN2896632Y - Inverted-connection protection circuit - Google Patents
Inverted-connection protection circuit Download PDFInfo
- Publication number
- CN2896632Y CN2896632Y CN 200620014093 CN200620014093U CN2896632Y CN 2896632 Y CN2896632 Y CN 2896632Y CN 200620014093 CN200620014093 CN 200620014093 CN 200620014093 U CN200620014093 U CN 200620014093U CN 2896632 Y CN2896632 Y CN 2896632Y
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- diode
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- power sense
- sense circuit
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Abstract
The model utility discloses a reversed polarity protection circuit comprising a power supply detection circuit; a resistance unit connected with the power supply detection circuit in parallel; a diode unit with a positive pole connected with the power supply detection circuit and a negative pole connected with a grounding terminal; or the positive pole is connected with power supply inlet port while the negative pole is connected with power supply detection circuit. In view of that the protection circuit accomplished with current technologies is costly and larger while the circuit performance is not reliable, the model utility adopts a rated resistance to limit voltages and adopts diodes to limit reversed current so as to accomplish a reliable reversed joint protection circuit with lower costs and a smaller volume.
Description
Technical field
The utility model relates to electronic circuit field, specifically, relates to a kind of reverse-connection protection circuit.
Background technology
In Circuits System management and the control, often need to detect power supply circuits and whether power on.Since detected voltage and different with reference to the voltage levvl and the reference ground thereof of ground and testing circuit, thus need to adopt isolation technology that detected voltage and testing circuit are isolated, to protect testing circuit.As shown in Figure 1, be a kind of power sense circuit commonly used, input voltage is connected to the drive end of the Light-Emitting Diode D1 of optocoupler through current limliting divider resistance R1, and behind the power supply electrifying, the light-emitting diode of optocoupler is lighted, and the output stage of optocoupler is opened.Late-class circuit just can judge by the electric current of power sense circuit and the variation of voltage under the on off state that detects optocoupler whether power supply powers on.
The resistance of current limliting divider resistance R1 is determined that by the size of detected voltage the principle of selecting R1 is to make the value of the current i that flows into testing circuit be fit to the input current level of D1 when operate as normal.Generally, the forward conduction voltage of light-emitting diode is approximately 0.7V, so the computing formula of i is:
The conclusion that draws is that the value of i is a milliampere rank.
As shown in Figure 2; when project installation; through regular meeting since misoperation the input voltage of equipment is connect instead; the light-emitting diode D1 of optocoupler is in reverse blocking state; the current i that can flow through is minimum, and reverse current i's is big or small different under different light-emitting diodes and the different temperatures environment, but the most very much not can surpass tens microamperes of ranks; the voltage at R1 two ends will be than little thousands of times under the normal power supply situation, and promptly the voltage of input almost all drops to the D1 two ends.If detected voltage is greater than the reverse withstand voltage of the light-emitting diode D1 of optocoupler, optocoupler will be reversed and puncture to damaging, and causes the circuit cisco unity malfunction.
At above problem, prior art has a kind of reverse-connection protection circuit, adopt at testing circuit front end oppositely clamping diode in parallel, and the method for connecting with resettable fuse realizes the protection to power sense circuit.As shown in Figure 3, under the situation of normal power supply, the light-emitting diode forward conduction of optocoupler, electric current through inflow power sense circuit after the current limliting divider resistance R1 current limliting is very little, oppositely clamping diode D2 oppositely ends, and flows through minimum electric current, and resettable fuse is in conducting state.
Under power supply reversal connection situation; reverse clamping diode D2 forward conduction; flow through very big electric current; resettable fuse enters the insurance guard mode; show very big impedance; input voltage almost all drops to the resettable fuse two ends, and the voltage at power sense circuit two ends has only the forward conduction voltage swing of D2, can not cause power sense circuit to damage.
But there is following shortcoming in this reverse-connection protection circuit of prior art:
1. oppositely clamping diode needs to bear other forward conduction electric current of ampere level, oppositely withstand voltage need be greater than the absolute value of detected supply voltage, device cost is higher;
2. need to use resettable fuse, cause the circuit volume big, overall cost height;
3. power supply connects inverse time, and the electric current that flows through protective circuit is very big, oppositely on clamping diode and the resettable fuse sizable power consumption is arranged all, requires wiring board to walk live width, otherwise device and circuit board burnt easily, and circuit performance is unreliable.
The utility model content
The utility model is at protective circuit cost height in the prior art, and volume is big, and the insecure shortcoming of circuit performance provides the reverse-connection protection circuit that a kind of cost is low, volume is little, reliability is high.
A kind of reverse-connection protection circuit comprises power sense circuit;
Resistance unit, in parallel with power sense circuit;
Diode, its positive pole links to each other with power sense circuit, and its negative pole links to each other with an earth terminal; Or its positive pole links to each other with power input, and its negative pole links to each other with power sense circuit.
Described resistance unit is a fixed value resistance or at least two fixed value resistance series/parallels.
The equivalent impedance of the resistance of described resistance unit during much larger than the power sense circuit forward conduction, and much smaller than power sense circuit oppositely by the time the backward impedance value.
Described diode is a diode or at least two diode series/parallels.
The forward conduction voltage of described diode deducts the forward conduction voltage of power sense circuit less than detected voltage, and the electric current of diode forward maximum permissible current during greater than the power sense circuit forward conduction, and diode is reverse withstand voltage greater than detected voltage.
The utility model adopts fixed value resistance to carry out pressure limiting; adopt the diode limits reverse current, fixed value resistance and diode are very general electronic devices, and cost is low; volume is little; connect under the anti-situation at power supply, power consumption own is little, and is less demanding to the cabling of wiring board; the dependable performance of circuit; so this reverse-connection protection circuit that the utility model provides has cost low, volume is little, the advantage that reliability is high.
Description of drawings
Fig. 1 is prior art power sense circuit figure;
Fig. 2 is the power sense circuit figure of prior art electric voltage reverse-connection;
Fig. 3 is prior art reverse-connection protection circuit figure;
Fig. 4 is the utility model reverse-connection protection circuit figure;
Reverse current distribution map when Fig. 5 adopts the BAV99 diode for the utility model.
Embodiment
Below by drawings and Examples, the technical solution of the utility model is described in further detail.
As shown in Figure 4; reverse-connection protection circuit comprises power sense circuit; fixed value resistance R2 is connected across the power sense circuit two ends; in parallel with it; the positive pole of diode D2 links to each other with power sense circuit, and its negative pole links to each other with an earth terminal, and wherein power sense circuit comprises a light-emitting diode D1, certain value resistance R 1; the positive pole of light-emitting diode D1 links to each other with power input by certain value resistance R 1, and the negative pole of light-emitting diode D1 links to each other with the positive pole of diode D2.Fixed value resistance R2 also can adopt the mode of two fixed value resistance series/parallels or two above fixed value resistance series/parallels to substitute in actual applications; Diode D2 equally also can adopt the mode of two diode series/parallels or two above diode series/parallels to substitute.Power sense circuit is a prior art, and a simple embodiment only is provided among Fig. 4, and the power sense circuit in the practical application has multiple.
The situation, the positive pole of diode D2 links to each other with power input in Fig. 4, and its negative pole links to each other with power sense circuit, equally also can realize reverse connecting protection.
Equivalent impedance when wherein the resistance of fixed value resistance R2 is much larger than the power sense circuit forward conduction, and much smaller than power sense circuit oppositely by the time the backward impedance value; The forward conduction voltage of diode deducts the forward conduction voltage of power sense circuit less than detected voltage, and the electric current of diode forward maximum permissible current during greater than the power sense circuit forward conduction, and diode is reverse withstand voltage greater than detected voltage.
Fixed value resistance R2 and diode D2 needs when satisfying above-mentioned requirements are adjusted according to the size that detects voltage.
With the BAV99 diode is example, the relation of reverse current and voltage and ambient temperature as shown in Figure 5 when diode D2 oppositely ended, abscissa is the reverse voltage at diode D2 two ends, ordinate is the reverse current of diode under the varying environment temperature, and the reverse current of visible diode D2 can not surpass 10 microamperes of ranks.If the scope of detected voltage is in 10V to 50V scope, between 5M ohm, select for use 100 kilohms fixed value resistance to satisfy above-mentioned requirements this moment to the resistance value that diode reverse shows when ending at 1M ohm.Common BAB99 diode, its reverse withstand voltage is 70 volts, selects 100 kilohms fixed value resistance for use, can be the effect that the power sense circuit of 5V to 70V reaches reverse connecting protection to input voltage.
In Fig. 4, when normally powering on, input supply voltage, the diode D2 and the diode D1 that gives out light are in the forward conduction state, the voltage at diode D2 two ends is about 0.7V, and is very little with respect to input voltage, so input supply voltage almost all drops between the AB two ends, be that voltage between the AB two ends almost just equals input voltage, thereby adopt diode D2 can not influence the normal detection of power supply.The voltage at light-emitting diode D1 two ends when forward conduction also is about 0.7V, electric current is 10 milliamperes of ranks, therefore, light-emitting diode D1 impedance when forward conduction is about 70 ohm, this moment, the resistance of fixed value resistance R2 was very big with respect to the resistance of power sense circuit, the electric current that flows through fixed value resistance R2 is very little, so can not cause circuit abnormality.
Power supply connects inverse time; input supply voltage; diode D2 and light-emitting diode D1 are in reverse blocking state; diode D2 and light-emitting diode D1 show very big impedance; because fixed value resistance R2 is in parallel with power sense circuit; so the impedance between the AB two ends mainly shows as the resistance of fixed value resistance R2; this impedance is very little with the impedance phase ratio at diode D2 two ends; so input voltage mainly drops to diode D2 two ends; the voltage that drops to the testing circuit two ends is minimum; be that voltage between the AB two ends is minimum, can not cause testing circuit to damage, thereby reach the purpose of protection testing circuit.
The forward conduction voltage of diode about 0.7V, is a very little value all in the practical application, and forward allows maximum current tens milliamperes of ranks, and oppositely withstand voltage big diode is very general, and low price, and volume is also very little.Also very general on the market of fixed value resistance, and cost is low.So the reverse-connection protection circuit that the utility model provides has the advantage that cost is low, volume is little, reliability is high.
The above; only for the preferable embodiment of the present invention, but protection scope of the present invention is not limited thereto, and anyly is familiar with those skilled in the art in the technical scope that the present invention discloses; the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claim.
Claims (5)
1, a kind of reverse-connection protection circuit is characterized in that, comprising:
Power sense circuit;
Resistance unit, in parallel with power sense circuit;
Diode, its positive pole links to each other with power sense circuit, and its negative pole links to each other with an earth terminal; Or its
Positive pole links to each other with power input, and its negative pole links to each other with power sense circuit.
2, circuit according to claim 1 is characterized in that, described resistance unit is a fixed value resistance or at least two fixed value resistance series/parallels.
3, circuit according to claim 2 is characterized in that, the equivalent impedance of the resistance of described resistance unit during much larger than the power sense circuit forward conduction, and much smaller than power sense circuit oppositely by the time the backward impedance value.
4, circuit according to claim 1 is characterized in that, described diode is a diode or at least two diode series/parallels.
5, circuit according to claim 4, it is characterized in that, the forward conduction voltage of described diode deducts the forward conduction voltage of power sense circuit less than detected voltage, and the electric current of diode forward maximum permissible current during greater than the power sense circuit forward conduction, and diode is reverse withstand voltage greater than detected voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200620014093 CN2896632Y (en) | 2006-05-19 | 2006-05-19 | Inverted-connection protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200620014093 CN2896632Y (en) | 2006-05-19 | 2006-05-19 | Inverted-connection protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2896632Y true CN2896632Y (en) | 2007-05-02 |
Family
ID=38066205
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200620014093 Expired - Fee Related CN2896632Y (en) | 2006-05-19 | 2006-05-19 | Inverted-connection protection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2896632Y (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105896516A (en) * | 2016-06-12 | 2016-08-24 | 许继集团有限公司 | Misconnection protection circuit for two paths of different input voltage grades |
| CN107561338A (en) * | 2016-09-30 | 2018-01-09 | 国家电网公司 | Straight-flow system overhauls voltage detector |
| WO2021253155A1 (en) * | 2020-06-15 | 2021-12-23 | 华为数字能源技术有限公司 | Protection circuit for preventing misconnection of input ends, and photovoltaic power generation system |
-
2006
- 2006-05-19 CN CN 200620014093 patent/CN2896632Y/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105896516A (en) * | 2016-06-12 | 2016-08-24 | 许继集团有限公司 | Misconnection protection circuit for two paths of different input voltage grades |
| CN105896516B (en) * | 2016-06-12 | 2018-11-09 | 许继集团有限公司 | A kind of misconnection protection circuit of two-way difference input voltage grade |
| CN107561338A (en) * | 2016-09-30 | 2018-01-09 | 国家电网公司 | Straight-flow system overhauls voltage detector |
| CN107561338B (en) * | 2016-09-30 | 2024-03-08 | 国家电网公司 | DC system maintenance voltage detector |
| WO2021253155A1 (en) * | 2020-06-15 | 2021-12-23 | 华为数字能源技术有限公司 | Protection circuit for preventing misconnection of input ends, and photovoltaic power generation system |
| CN114080741A (en) * | 2020-06-15 | 2022-02-22 | 华为数字能源技术有限公司 | Protection circuit for preventing input end misconnection and photovoltaic power generation system |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20070502 Termination date: 20100519 |