CN101958538B - Circuit protection system - Google Patents
Circuit protection system Download PDFInfo
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- CN101958538B CN101958538B CN 201010169970 CN201010169970A CN101958538B CN 101958538 B CN101958538 B CN 101958538B CN 201010169970 CN201010169970 CN 201010169970 CN 201010169970 A CN201010169970 A CN 201010169970A CN 101958538 B CN101958538 B CN 101958538B
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Abstract
The invention relates to a circuit protection system comprising a static protection element and a leakage current protection circuit, wherein the static protection element is perforatively coupled with the input end of an integrated circuit, and the input end of the integrated circuit is used for receiving an input signal from a signal source; the leakage current protection circuit is provided with a filter capacitor coupled with the static protection element; and when the input signal has leakage currents and the leakage currents contain AC components, the filter capacitor has high impedance so as to prevent the leakage currents generated due to an AC power supply from entering the static protection element.
Description
Technical field
The present invention is relevant for a kind of circuit protection system, particularly relevant for a kind of circuit protection system of avoiding being subjected to the leakage current that produces because of AC power to damage.
Background technology
Please refer to Fig. 1.The schematic diagram of the electrostatic protection element of Fig. 1 prior art.Electrostatic protection element 100 is used for preventing that integrated circuit (integrated circuit, IC) 101 is subject to electrostatic damage.Electrostatic protection element 100 is coupled to the input P of integrated circuit 101
INInput P
INIn order to from signal source S
INReceive input signal.Electrostatic protection element 100 comprises Zener diode (Zener diode) ZD
1With ZD
2Zener diode ZD
1First end be coupled to input P
INZener diode ZD
1The second end be coupled to Zener diode ZD
2The second end.Zener diode ZD
2First end hold (ground) with being coupled to.When input signal has the composition of static, because the current potential of static is higher, and make Zener diode ZD
1Reverse conducting.So, electrostatic protection element 100 sees through Zener diode ZD
1With ZD
2Static is guided to end, be subject to electrostatic damage to prevent integrated circuit 101.
Yet, except static, signal source S
INMay also can be subject to AC power V
ACLeakage current I
LEAKImpact.When input signal has leakage current I
LEAKAnd this leakage current I
LEAKHave frequency and be essentially AC power V
ACThe composition of frequency (that is to say I
LEAKFor because of AC power V
ACAnd the leakage current that produces) time, the current potential of input signal can be higher and make electrostatic protection element 100 conductings.This moment AC power V
ACLeakage current I
LEAKSee through electrostatic protection element 100 and flow to ground end (as shown in Figure 1).Due to AC power V generally speaking
ACLeakage current I
LEAKExceed the electric current that electrostatic protection element 100 can carry, so electrostatic protection element 100 can be damaged.So, when there being again static to input to input P
INThe time, this moment, the electrostatic protection element 100 that damaged can't Protective IC 101, and made integrated circuit 101 be subject to electrostatic damage.
Summary of the invention
In view of this, the invention provides a kind of circuit protection system, except the effect of playing electrostatic protection, can also prevent the destruction of the leakage current that AC power produces.
According to the circuit protection system that purpose of the present invention proposes, be coupled to the input of integrated circuit, this input is in order to receive input signal from signal source, and this circuit protection system comprises: electrostatic protection element; And leakage current protective circuit, this leakage current protective circuit comprises: the first filter capacitor, be coupled to this electrostatic protection element, when this input signal has leakage current and this leakage current when having alternating component, this first filter capacitor is that high impedance is to avoid entering this electrostatic protection element because of this leakage current, when this input signal has frequency and is the composition of frequency of static, this first filter capacitor be Low ESR so that this electrostatic current through this electrostatic protection element; And first current-limiting resistance, be coupled between this signal source and this integrated circuit, be used for limiting the size of current that inputs to this integrated circuit from this signal source, to prevent that this integrated circuit is subjected to damage because of the leakage current that AC power produces; Wherein, design the capacitance of this first filter capacitor according to the input impedance of this first current-limiting resistance and this integrated circuit.
According to the circuit protection system that purpose of the present invention proposes, wherein the scope of the capacitance of this first filter capacitor is 0.5 μ F ~ 4 μ F.
According to the circuit protection system that purpose of the present invention proposes, wherein this first filter capacitor and this electrostatic protection element are serially connected with between this input and ground end.
According to the circuit protection system that purpose of the present invention proposes, wherein this electrostatic protection element comprises: the first Zener diode comprises: first end is coupled to this input; And second end; And second Zener diode, comprise: first end, end with being coupled to; And second end, be coupled to this second end of this first Zener diode; Wherein this first filter capacitor is coupled between this first end of this input and this first Zener diode, or this first filter capacitor is coupled between this first end and this ground end of this second Zener diode.
Circuit protection system according to purpose proposition of the present invention; wherein this leakage current protective circuit separately comprises: the second filter capacitor; be coupled between this first end and this ground end of this second Zener diode, and this first filter capacitor is coupled between this first end of this input and this first Zener diode.
According to the circuit protection system that purpose of the present invention proposes, wherein this electrostatic protection element comprises: the first diode comprises: first end is coupled to this input; And second end, be coupled to the first voltage source; And second diode, comprise: first end is coupled to the second voltage source; And second end, be coupled to this first end of this first diode; Wherein this first filter capacitor is coupled to this first end of this input, this first diode and this second end of this second diode.
According to the circuit protection system that purpose of the present invention proposes, wherein this first current-limiting resistance is coupled between this input and this integrated circuit, or this first current-limiting resistance is coupled between this signal source and this input.
Circuit protection system according to purpose proposition of the present invention; wherein when this first current-limiting resistance is coupled between this input and this integrated circuit; this leakage current protective circuit separately comprises the second current-limiting resistance and is coupled between this signal source and this input, is used for coordinating this first current-limiting resistance to input to the size of current of this integrated circuit from this signal source with restriction.
By above-mentioned leakage current protective circuit; when making AC power produce the higher leakage current of frequency; utilize the high impedance filter capacitor to prevent that this leakage current from pouring in electrostatic protection element, the effect that realization can be played electrostatic protection can prevent again the effect that leakage current destroys.
Below in conjunction with accompanying drawing, the present invention is elaborated.
Description of drawings
Fig. 1 is the schematic diagram of the electrostatic protection element of explanation prior art.
Fig. 2 is the schematic diagram according to the circuit protection system of the first embodiment of the present invention.
Fig. 3 is the schematic diagram of circuit protection system according to a second embodiment of the present invention.
Fig. 4 is the schematic diagram of the circuit protection system of a third embodiment in accordance with the invention.
Fig. 5 is the schematic diagram of the circuit protection system of a fourth embodiment in accordance with the invention.
Fig. 6 is the schematic diagram of circuit protection system according to a fifth embodiment of the invention.
Fig. 7 is the schematic diagram that the D-sub joint is used the example of circuit protection system of the present invention.
Embodiment
Please refer to Fig. 2, the first embodiment of the present invention, circuit protection system 200 comprises electrostatic protection element 210, and leakage current protective circuit 220.Electrostatic protection element 210 is used for preventing that integrated circuit 201 is subject to electrostatic damage.Electrostatic protection element 210 is coupled to the input P of integrated circuit 201
INInput P
INIn order to from signal source S
INReceive input signal.Electrostatic protection element 210 comprises Zener diode ZD
1With ZD
2, its operation principle is as described in the explanation of Fig. 1, therefore repeat no more.Need be appreciated that except electrostatic protection element of the present invention, may still have other electrostatic protection elements to can be applicable to the present invention.Leakage current protective circuit 220 comprises filter capacitor C
F1, and current-limiting resistance R
L1Filter capacitor C
F1Be coupled to electrostatic protection element 210 and input P
INBetween.Generally speaking, the impedance of electric capacity can represent by following formula:
Z=1/(j×2×π×f×C)…(1)；
Wherein Z represents impedance, and j represents imaginary number, and π represents circumference ratio, and f represents the frequency by the signal of filter capacitor, and C represents the capacitance of electric capacity.Therefore, worked as by filter capacitor C as can be known by formula (1)
F1The frequency of signal when being high frequency, filter capacitor C
F1Impedance lower; When passing through filter capacitor C
F1The frequency of signal when being low frequency, filter capacitor C
F1Impedance higher.In Fig. 2, signal source S
INInput signal may be subject to static and AC power V
ACImpact, wherein the radio-frequency component that comprises of the discharge waveform of static is to more than 300MHz, the characteristic of static is known, therefore repeat no more.And AC power V
ACFrequency (that is to say, the frequency of static is relative AC power V for 60Hz
ACFrequency be high frequency).Therefore, as long as according to current-limiting resistance R
L1Suitably design filter capacitor C with the input impedance of integrated circuit 201
F1Capacitance, can have frequency in input signal source and be essentially AC power V
ACThe composition of frequency the time, make filter capacitor C
F1Be high impedance, and when input signal has frequency and is essentially the composition of frequency of static, make filter capacitor C
F1Be Low ESR.Thus, has leakage current I when input signal
LEAKWhen having alternating component, due to filter capacitor C
FBe high impedance, so filter capacitor C
FCan avoid the leakage current I because of the AC power generation
LEAKEnter electrostatic protection element 210, impaired to prevent electrostatic protection element 210.At this moment, leakage current I
LEAKCan be from input P
INFlow to integrated circuit 201.Yet due to current-limiting resistance R
L1Can limit from signal source S
INFlow to the size of the electric current of integrated circuit 201, so leakage current protective circuit 220 also can be avoided leakage current I
LEAK Integrated circuit 201 is caused damage.When input signal has frequency and is essentially the composition of frequency of static, due to filter capacitor C
F1Be Low ESR, so static is from input P
INFlow to electrostatic protection element 210.This moment, static can make Zener diode ZD
1Reverse conducting, so electrostatic protection element 210 sees through Zener diode ZD
1With ZD
2Static is guided to end, to eliminate static.Generally speaking, can design filter capacitor C
F1Capacitance between 0.5 μ F ~ 4 μ F, especially as filter capacitor C
F1Capacitance between 1 μ F ~ 2.2 μ F the time, it prevents that electrostatic protection element 210 is subjected to leakage current I
LEAKDamage and the best results of keeping electrostatic protection element 210 elimination static.
Please refer to Fig. 3, the second embodiment of the present invention, circuit protection system 300 comprises electrostatic protection element 210, and leakage current protective circuit 320.Compared to leakage current protective circuit 220, in leakage current protective circuit 320, filter capacitor C
F1Be coupled between electrostatic protection element 210 and ground end.Yet, due to filter capacitor C
F1Still maintain on the discharge path of electrostatic protection element 200, so filter capacitor C
F1Still keep and have the described function of Fig. 2.In addition, the two ends (as Fig. 2,3) that two filter capacitors lay respectively at electrostatic protection element 210 can be set simultaneously, also can reach previous described function.
Please refer to Fig. 4, the third embodiment of the present invention, circuit protection system 500 comprises electrostatic protection element 210, and leakage current protective circuit 520.Compared to leakage current protective circuit 220, the current-limiting resistance R in leakage current protective circuit 520
L1Be coupled to signal source S
INWith input P
INBetween.At this moment, current-limiting resistance R
L1Restriction is from signal source S
INFlow to input P
INThe size of electric current.In other words, current-limiting resistance R
L1Still can limit from signal source S
INFlow to the size of the electric current of integrated circuit 201.Therefore, when because of AC power V
ACThe leakage current I that produces
LEAKFrom signal source S
INSee through input P
INWhen flowing to integrated circuit 201, current-limiting resistance R
L1But limit leakage current I
LEAKSize of current, impaired to prevent integrated circuit 201.Similarly, the current-limiting resistance in Fig. 2 and Fig. 4 also can exist simultaneously.
Please refer to Fig. 5, the fourth embodiment of the present invention, circuit protection system 900 comprises electrostatic protection element 910, and leakage current protective circuit 220.The structure of leakage current protective circuit 220 and operation principle are described as the explanation of Fig. 2, therefore repeat no more.Compared to circuit protection system 200, the electrostatic protection element 910 in circuit protection system 900 comprises diode D
1With D
2Diode D
1The second end be coupled to voltage source V
SSDiode D
1First end be coupled to diode D
2The second end; Diode D
2First end be coupled to voltage source V
DDGenerally speaking, V
DDBe the supply voltage of integrated circuit 201, and diode D
1With D
2Conducting voltage V
ONBe about 0.7V.When input signal has frequency and is essentially the composition of frequency of static, filter capacitor C
F1Be Low ESR, this moment, static flowed to electrostatic protection element 910 from input PIN.If the current potential of static is higher than (V
DD+ V
ON) time, diode D
2Conducting with static guiding to voltage source V
DDIf the current potential of static is lower than (V
SS-V
ON) time, diode D
1Conducting can prevent that to eliminate static integrated circuit 201 is subject to electrostatic damage.
Please refer to Fig. 6, the fifth embodiment of the present invention, the current-limiting resistance R of circuit protection system 1000
L1Function narration as relevant in Fig. 4, therefore repeat no more.Similarly, the current-limiting resistance in Fig. 5 and Fig. 6 also can exist simultaneously.
Please refer to Fig. 7.Fig. 7 is the schematic diagram that a D-sub joint 1302 is used the example of circuit protection system of the present invention.In this example, D-sub joint 1302 is coupled between the integrated circuit 1301 of image original device and projector.For example, the image original device can be computer.D-sub joint 1302 is coupled to the input P of the integrated circuit 1301 in projector
IN1~ P
IN2, to transmit horizontal-drive signal H_SYNC and vertical synchronizing signal V_SYNC to integrated circuit 1301.Circuit protection system 1310 ~ 1320 can prevent that integrated circuit 1301 is subject to electrostatic damage, even and D-sub joint 1302 when transmitting synchronizing signal H_SYNC and V_SYNC with AC power V
ACThe leakage current I that produces
LEAK, circuit protection system 1310 ~ 1320 can not be subject to leakage current I yet
LEAKDamage.
By the detailed description of above better embodiment, hope can be known description feature of the present invention and spirit more, and with above-mentioned disclosed better embodiment, claim scope of the present invention is limited.On the contrary, its objective is that hope can contain in the scope of claim of being arranged in of various changes and tool equality institute of the present invention wish application.
Claims (8)
1. circuit protection system is coupled to the input of integrated circuit, and this input is characterized in that in order to receive input signal from signal source this circuit protection system comprises:
Electrostatic protection element; And
The leakage current protective circuit, this leakage current protective circuit comprises:
The first filter capacitor, be coupled to this electrostatic protection element, when this input signal has leakage current and this leakage current when having alternating component, this first filter capacitor is that high impedance is to avoid entering this electrostatic protection element because of this leakage current, when this input signal has frequency and is the composition of frequency of static, this first filter capacitor be Low ESR so that this electrostatic current through this electrostatic protection element; And
The first current-limiting resistance is coupled between this signal source and this integrated circuit, is used for limiting the size of current that inputs to this integrated circuit from this signal source, to prevent that this integrated circuit is subjected to damage because of the leakage current that AC power produces; Wherein, design the capacitance of this first filter capacitor according to the input impedance of this first current-limiting resistance and this integrated circuit.
2. circuit protection system as claimed in claim 1, it is characterized in that: the scope of the capacitance of this first filter capacitor is 0.5 μ F ~ 4 μ F.
3. circuit protection system as claimed in claim 1 is characterized in that: this first filter capacitor and this electrostatic protection element are serially connected with between this input and ground end.
4. circuit protection system as claimed in claim 1, it is characterized in that: this electrostatic protection element comprises:
The first Zener diode comprises:
First end is coupled to this input; And
The second end; And
The second Zener diode comprises:
First end, end with being coupled to; And
The second end is coupled to this second end of this first Zener diode;
Wherein this first filter capacitor is coupled between this first end of this input and this first Zener diode, or this first filter capacitor is coupled between this first end and this ground end of this second Zener diode.
5. circuit protection system as claimed in claim 4; it is characterized in that this leakage current protective circuit separately comprises: the second filter capacitor; be coupled between this first end and this ground end of this second Zener diode, and this first filter capacitor is coupled between this first end of this input and this first Zener diode.
6. circuit protection system as claimed in claim 1, it is characterized in that: this electrostatic protection element comprises:
The first diode comprises:
First end is coupled to this input; And
The second end is coupled to the first voltage source; And
The second diode comprises:
First end is coupled to the second voltage source; And
The second end is coupled to this first end of this first diode;
Wherein this first filter capacitor is coupled to this first end of this input, this first diode and this second end of this second diode.
7. circuit protection system as claimed in claim 1, it is characterized in that: this first current-limiting resistance is coupled between this input and this integrated circuit, or this first current-limiting resistance is coupled between this signal source and this input.
8. circuit protection system as claimed in claim 7; it is characterized in that: when this first current-limiting resistance is coupled between this input and this integrated circuit; this leakage current protective circuit separately comprises the second current-limiting resistance and is coupled between this signal source and this input, is used for coordinating this first current-limiting resistance to input to the size of current of this integrated circuit from this signal source with restriction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201010169970 CN101958538B (en) | 2010-04-07 | 2010-04-07 | Circuit protection system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201010169970 CN101958538B (en) | 2010-04-07 | 2010-04-07 | Circuit protection system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101958538A CN101958538A (en) | 2011-01-26 |
| CN101958538B true CN101958538B (en) | 2013-06-05 |
Family
ID=43485723
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201010169970 Expired - Fee Related CN101958538B (en) | 2010-04-07 | 2010-04-07 | Circuit protection system |
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| CN (1) | CN101958538B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9899832B2 (en) | 2015-08-23 | 2018-02-20 | Htc Corporation | Wearable device and electrostatic discharge protection circuit of the same |
| CN107425876A (en) * | 2017-08-31 | 2017-12-01 | 广东欧珀移动通信有限公司 | Electrostatic protection apparatus, radio circuit and electronic equipment |
| CN107359606A (en) * | 2017-08-31 | 2017-11-17 | 广东欧珀移动通信有限公司 | Electrostatic protection apparatus, radio circuit and electronic equipment |
| CN108054742A (en) * | 2017-12-21 | 2018-05-18 | 帝晶光电（深圳）有限公司 | One kind is used for TP anti-static protection circuits |
| CN110212508B (en) * | 2019-05-15 | 2021-09-10 | 明基智能科技（上海）有限公司 | Overcurrent protection system |
| TWI713279B (en) | 2019-05-17 | 2020-12-11 | 明基電通股份有限公司 | Over current protection system |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101517743A (en) * | 2006-09-29 | 2009-08-26 | 飞兆半导体公司 | Tapered voltage polysilicon diode electrostatic discharge circuit for power mosfets and ics |
| CN101584082A (en) * | 2007-01-10 | 2009-11-18 | 深圳Tcl新技术有限公司 | System and method for providing electrostatic discharge (esd) protection and electromagnetic interference (emi) protection |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007287853A (en) * | 2006-04-14 | 2007-11-01 | Fuji Xerox Co Ltd | Electrostatic electricity protection circuit, signal line, and power supply line |
-
2010
- 2010-04-07 CN CN 201010169970 patent/CN101958538B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101517743A (en) * | 2006-09-29 | 2009-08-26 | 飞兆半导体公司 | Tapered voltage polysilicon diode electrostatic discharge circuit for power mosfets and ics |
| CN101584082A (en) * | 2007-01-10 | 2009-11-18 | 深圳Tcl新技术有限公司 | System and method for providing electrostatic discharge (esd) protection and electromagnetic interference (emi) protection |
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| Publication number | Publication date |
|---|---|
| CN101958538A (en) | 2011-01-26 |
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Granted publication date: 20130605 Termination date: 20140407 |