CN202616987U - Circuit for reducing input impact current - Google Patents
Circuit for reducing input impact current Download PDFInfo
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- CN202616987U CN202616987U CN 201220185412 CN201220185412U CN202616987U CN 202616987 U CN202616987 U CN 202616987U CN 201220185412 CN201220185412 CN 201220185412 CN 201220185412 U CN201220185412 U CN 201220185412U CN 202616987 U CN202616987 U CN 202616987U
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Abstract
The utility model provides a circuit for reducing an input impact current, comprising an insurance and forward diode, a divider resistor, an RC loop, an MOS (Metal Oxide Semiconductor) transistor, a Zener diode and a current-limiting resistor, and a DC-DC (Direct Current-Direct Current) loop with a switch; wherein, the insurance and forward diode, the divider resistor, the RC loop and the MOS transistor are connected in order; the Zener diode and the current-limiting resistor are connected with the DC-DC loop with the switch; the Zener diode and the current-limiting resistor are connected with a power supply; the divider resistor, the RC loop, and the DC-DC loop with the switch are respectively grounded. An input power supply current limiting circuit comprises multiple current limiting loops, and can effectively provide a working current to an ATM (Automated Teller Machine) display and prevent an impact current of the ATM display in a boot moment thereof, thus the input power supply current limiting circuit has high consistency and high reliability.
Description
Technical field
The utility model relates to electronic technology field, relates in particular to a kind of minimizing ATM LCD impulse current circuit.
Background technology
ATM (ATM is the abbreviation of Automated Teller Machine, is translated into ATM) machine all has very big application in the whole world, the display of ATM is a window to the client, work in 24 hours.Because the region that relates to is wide, repair the comparison difficulty, cause cost height very.And for reliability, requiring display is more little good more to the influence of the system of ATM.The harshness very so whole design parameter just becomes.Being connected of ATM display and system is respectively power supply and signal.So the designing requirement to the part of power supply is very high.The design of ATM display must be to design according to non-maintaining mode.
General display all can add one or two bigger electrochemical capacitor at input, and for example 100 μ F/25V are used to reduce the ripple of importing power supply, and most important purpose is the interference that the assurance display is not imported power supply, steady operation.In power supply opening,, be equivalent to the electric capacity shorted to earth, can produce very big impulse current, like Fig. 1 because the voltage of electrochemical capacitor can not suddenly change.
When the 24V power supply powered on, system produced the impulse current of 13.6A, and times 500 μ S is like Fig. 2 and Fig. 3.The fuse of system end is the quick fuse of 2A/32V, according to the operating chacteristics of fuse, can not satisfy client's life requirements.
Traditional approach can be at the connect thermistor of NTC of input, like Fig. 4.(NTC is the abbreviation of Negative Temperature Coefficient, and so-called NTC thermistor is exactly a negative tempperature coefficient thermistor).Under situation about powering on; Because resistance generates heat suddenly, be resistance value is bigger, control impulse current in this way; But in the application of our this little electric current; It is very little that the resistance of the resistance of NTC can not become always, to such an extent as to that the pressure drop on thermistor becomes is very big, from but bigger voltage ripple is introduced in the circuit input of back.Like Fig. 5, impulse current reduces to about 9A.
The utility model content
Do not meet the predicament that environment for use requires for solving existing loop, be necessary to provide a kind of cheap, consistency and reliability all to need very high power supply to import current-limiting circuit.
A kind of minimizing input impulse current circuit; It comprises insurance and forward diode, divider resistance, RC loop, metal-oxide-semiconductor, voltage stabilizing didoe and current-limiting resistance and belt switch DC-DC loop; Said insurance is connected with forward diode, divider resistance, RC loop and metal-oxide-semiconductor successively; Said voltage stabilizing didoe and current-limiting resistance are connected with belt switch DC-DC loop; Said voltage stabilizing didoe and current-limiting resistance are connected with power supply, and said divider resistance, RC loop and belt switch DC-DC loop be ground connection respectively.
As the further improvement of the utility model, said divider resistance comprises the resistance R 90 and resistance R 91 of series connection.
As the further improvement of the utility model, said RC loop comprises the capacitor C 70 and resistance R 91 of series connection.
As the further improvement of the utility model, the two ends of capacitor C 70 are electrically connected with said metal-oxide-semiconductor, an end ground connection of resistance R 91.
As the further improvement of the utility model, said voltage stabilizing didoe and current-limiting resistance comprise the resistance R 93 and voltage stabilizing didoe D18 of series connection, and resistance R 93 is connected with belt switch DC-DC loop, and voltage stabilizing didoe D18 is connected with power supply.
As the further improvement of the utility model, said belt switch DC-DC loop comprises soft starting circuit.
Further improvement as the utility model is provided with inductance L 3 between said insurance and forward diode and the divider resistance.
As the further improvement of the utility model, the fuse electric current reduction coefficient in insurance and the forward diode 10 is 0.75.
Compared to prior art; This input power supply current-limiting circuit comprises multiple electric current limit circuit; Can be effectively for the ATM display provide operating current, and prevent it at the start impulse current of moment, thus make above-mentioned input power supply current-limiting circuit consistency height and reliability high.
Description of drawings
Fig. 1 is a prior art power supply input current-limiting circuit;
Fig. 2 is the measured current waveform that Fig. 1 imports current-limiting circuit;
Fig. 3 is that Fig. 1 imports the measured current waveform that current-limiting circuit is dwindled;
Fig. 4 is another power supply input current-limiting circuit of prior art;
Fig. 5 is the measured current waveform that Fig. 4 imports current-limiting circuit;
Fig. 6 is the block diagram of the utility model structure input power supply current-limiting circuit preferred embodiments;
Fig. 7 is the electrical block diagram of input power supply current-limiting circuit shown in Figure 6;
Fig. 8 is the measured current waveform of input current-limiting circuit shown in Figure 7;
Fig. 9 is a temperature reduction curve;
Figure 10 is that metal-oxide-semiconductor is the security interval curve.
Embodiment
Below in conjunction with description of drawings and embodiment the utility model is further specified.
Like Fig. 6 and shown in Figure 7; A kind of minimizing input impulse current circuit; It comprises insurance and forward diode 10, divider resistance 20, RC loop 30, metal-oxide-semiconductor 40, voltage stabilizing didoe and current-limiting resistance 50 and belt switch DC-DC loop 60; Said insurance is connected with forward diode 10, divider resistance 20, RC loop 30 and metal-oxide-semiconductor 40 successively; Said voltage stabilizing didoe and current-limiting resistance 50 are connected with belt switch DC-DC loop 60, and said voltage stabilizing didoe and current-limiting resistance 50 are connected with power supply, and said divider resistance 20, RC loop 30 and belt switch DC-DC loop 60 be ground connection respectively.
Said divider resistance 20 comprises the resistance R 90 and resistance R 91 of series connection.Said RC loop 30 comprises the capacitor C 70 and resistance R 91 of series connection.The two ends of capacitor C 70 are electrically connected with said metal-oxide-semiconductor 40, an end ground connection of resistance R 91.Said voltage stabilizing didoe and current-limiting resistance 50 comprise the resistance R 93 and voltage stabilizing didoe D18 of series connection, and resistance R 93 is connected with belt switch DC-DC loop 60, and voltage stabilizing didoe D18 is connected with power supply.Said belt switch DC-DC loop 60 comprises soft starting circuit.Be provided with inductance L 3 between said insurance and forward diode 10 and the divider resistance 20.
Wherein insurance and forward diode 10 are responsible for two functions: the protection of overcurrent and the protection of reverse voltage continuously.Divider resistance 20 is responsible for the GS voltage difference of metal-oxide-semiconductor.When powering on, the voltage of electrochemical capacitor C70 (see figure 7) can not suddenly change, and making the voltage between the GS of metal-oxide-semiconductor is 0, and metal-oxide-semiconductor does not carry out conducting, along with the charging interval decision metal-oxide-semiconductor of C70 and R91 gets into the saturation region by the amplification region, the last complete conducting of metal-oxide-semiconductor.The conducting resistance of metal-oxide-semiconductor is smaller, can not introduce too big power supply ripple.Computing formula is: F=1/RC.Voltage stabilizing didoe and current-limiting resistance 50 mainly are responsible for when input voltage does not reach rated voltage, and work can not carried out in the DC-DC loop of back.Belt switch DC-DC loop 60 mainly provides the ON/OFF switch.In addition, this loop comprises the SOFT-START soft start function, thereby guarantees that more impulse current is excessive.
Through test, the impulse current behind the modification circuit is 2.385A, and the attack time is 2mS.Like Fig. 8.
Through following calculating, can meet the demands with 1.5A/32V, when abnormal conditions took place, the 1.5A fuse was disconnected earlier, thus the fuse of protection system 2A/32V makes the fail safe of system reach designing requirement.
Fuse is selected:
1) fuse electric current reduction coefficient: Of=0.75
2) the temperature reduction coefficient 60 ℃ the time: (find from temperature reduction curve, like Fig. 9, Fig. 9 abscissa is an ambient temperature to Tf=0.95, and ordinate is: reduction coefficient)
3) primary election fuse rated current (peak current 0.436mA):
In=0.436/0.75/0.95=0.612A,
Selecting rated current for use is 1A or above FUSE; The 1A of 451/453 series that Littlefuse provides and the rated voltage of above fuse have all surpassed the 24VDC of project demand, so the surge current peak value 2.385A of the no problem mainboard of rated voltage all greater than 24V; Specified breaking capacity 50A less than fuse; Fail safe during disjunction does not have problem, (if the surge peak value greater than 50A, then need be considered from the power angle).
4) calculate the energy value of surge current according to the impulse waveform of known applications
Ir2t?=?2.3852*0.004=?5.688*0.004=0.02275A2s
Need bear more than 100,000 times
The general relation of the If2t of Littelfuse fuse and Ir2t
Ir2t≤22% If2t 100,000 times
Ir2t≤29% If2t 10,000 times
Ir2t≤38% If2t 1,000 time
If2t?≥?0.02275/22%?≥?0.1034?A2s
The I-t curve is found 0451/453 1.5A and when 2.385A, is fused summary at 0.15s, greater than 4ms, is safe and reliable.Like Figure 10.The abscissa of Figure 10 is a drain source voltage, and ordinate is a drain-source current, and abscissa unit is a volt, and the unit of ordinate is an ampere.
Above content is the further explain that combines concrete preferred implementation that the utility model is done, and can not assert that the practical implementation of the utility model is confined to these explanations.For the those of ordinary skill of technical field under the utility model, under the prerequisite that does not break away from the utility model design, can also make some simple deduction or replace, all should be regarded as belonging to the protection range of the utility model.
Claims (8)
1. one kind is reduced input impulse current circuit; It is characterized in that: it comprises insurance and forward diode (10), divider resistance (20), RC loop (30), metal-oxide-semiconductor (40), voltage stabilizing didoe and current-limiting resistance (50) and belt switch DC-DC loop (60); Said insurance is connected with forward diode (10), divider resistance (20), RC loop (30) and metal-oxide-semiconductor (40) successively; Said voltage stabilizing didoe and current-limiting resistance (50) are connected with belt switch DC-DC loop (60); Said voltage stabilizing didoe and current-limiting resistance (50) are connected with power supply, and said divider resistance (20), RC loop (30) and belt switch DC-DC loop (60) be ground connection respectively.
2. minimizing input impulse current circuit according to claim 1, it is characterized in that: said divider resistance (20) comprises the resistance R 90 and resistance R 91 of series connection.
3. minimizing input impulse current circuit according to claim 2, it is characterized in that: said RC loop (30) comprises the capacitor C 70 and resistance R 91 of series connection.
4. minimizing input impulse current circuit according to claim 3, it is characterized in that: the two ends of capacitor C 70 are electrically connected with said metal-oxide-semiconductor (40), an end ground connection of resistance R 91.
5. minimizing input impulse current circuit according to claim 4; It is characterized in that: said voltage stabilizing didoe and current-limiting resistance (50) comprise the resistance R 93 and voltage stabilizing didoe D18 of series connection; Resistance R 93 is connected with belt switch DC-DC loop (60), and voltage stabilizing didoe D18 is connected with power supply.
6. according to any described minimizing input impulse current circuit of claim 1 to 5, it is characterized in that: said belt switch DC-DC loop (60) comprises soft starting circuit.
7. according to any described minimizing input impulse current circuit of claim 1 to 5, it is characterized in that: be provided with inductance L 3 between said insurance and forward diode (10) and the divider resistance (20).
8. according to any described minimizing input impulse current circuit of claim 1 to 5, it is characterized in that: the fuse electric current reduction coefficient in insurance and the forward diode (10) is 0.75.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220185412 CN202616987U (en) | 2012-04-27 | 2012-04-27 | Circuit for reducing input impact current |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220185412 CN202616987U (en) | 2012-04-27 | 2012-04-27 | Circuit for reducing input impact current |
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| Publication Number | Publication Date |
|---|---|
| CN202616987U true CN202616987U (en) | 2012-12-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220185412 Expired - Lifetime CN202616987U (en) | 2012-04-27 | 2012-04-27 | Circuit for reducing input impact current |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103199688A (en) * | 2013-04-09 | 2013-07-10 | 许继集团有限公司 | Switching power supply and power-on impact current suppression method thereof |
-
2012
- 2012-04-27 CN CN 201220185412 patent/CN202616987U/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103199688A (en) * | 2013-04-09 | 2013-07-10 | 许继集团有限公司 | Switching power supply and power-on impact current suppression method thereof |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C56 | Change in the name or address of the patentee |
Owner name: SHENZHEN BIGTIDE TECHNOLOGY CO., LTD. Free format text: FORMER NAME: SHENZHEN JUCHAO TECHNOLOGY CO., LTD. |
|
| CP03 | Change of name, title or address |
Address after: 518000 Guangdong Province, Shenzhen New District of Longhua City, Huarong Road No. 397 Fu Long Industrial Zone 8 Patentee after: SHENZHEN BIGTIDE TECHNOLOGY CO., LTD. Address before: 518000, Shenzhen, Guangdong province Nanshan District Ping Shan Road, Pingshan large industrial park, 10 Patentee before: Shenzhen Juchao Technology Co., Ltd. |
|
| CP02 | Change in the address of a patent holder | ||
| CP02 | Change in the address of a patent holder |
Address after: 518000 517, building 7, Hengda fashion Huigu building (East District), Fulong Road, Tongsheng community, Dalang street, Longhua District, Shenzhen City, Guangdong Province Patentee after: SHENZHEN BIGTIDE TECHNOLOGY Co.,Ltd. Address before: Building 8, longfu Industrial Zone, 397 Huarong Road, Longhua New District, Shenzhen, Guangdong 518000 Patentee before: SHENZHEN BIGTIDE TECHNOLOGY Co.,Ltd. |
|
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20121219 |