JP3414690B2 - Circuit for transient voltage absorption - Google Patents
Circuit for transient voltage absorptionInfo
- Publication number
- JP3414690B2 JP3414690B2 JP2000071132A JP2000071132A JP3414690B2 JP 3414690 B2 JP3414690 B2 JP 3414690B2 JP 2000071132 A JP2000071132 A JP 2000071132A JP 2000071132 A JP2000071132 A JP 2000071132A JP 3414690 B2 JP3414690 B2 JP 3414690B2
- Authority
- JP
- Japan
- Prior art keywords
- transient voltage
- terminal
- circuit
- voltage protection
- protection element
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ＩＣなどをＥＳＤ
（静電放電）から守るために設けられる保護回路に関す
る。TECHNICAL FIELD The present invention relates to ESD of an IC or the like.
The present invention relates to a protection circuit provided to protect from (electrostatic discharge).
【０００２】[0002]
【従来の技術】従来、回路基板に組み入れられるＩＣな
どの回路を、静電気などによる過渡電圧から保護するた
めに、図１に示す過渡電圧保護素子が使用されている。
この保護素子としては、正常時は非常に大きな絶縁抵抗
であって回路の入出力信号に影響しない一方、過渡電圧
が発生した際には数ｎｓのオーダーで数Ω以下の低イン
ピーダンスに降下して過渡電圧を接地（ＧＮＤ）へ回避
させるという性質が必要で、ツェナーダイオードやバリ
スタ、ガスアレスタなどが使用される。このような過渡
電圧保護素子は、図示のように回路の端子と接地との間
に接続されて機能する。2. Description of the Related Art Conventionally, a transient voltage protection device shown in FIG. 1 is used to protect a circuit such as an IC incorporated in a circuit board from a transient voltage due to static electricity.
As a protection element, it normally has a very large insulation resistance and does not affect the input / output signals of the circuit, but when a transient voltage occurs, it drops to a low impedance of several Ω or less on the order of several ns. A property of avoiding a transient voltage to the ground (GND) is required, and a Zener diode, a varistor, a gas arrester or the like is used. Such a transient voltage protection device functions by being connected between the terminal of the circuit and the ground as shown.
【０００３】[0003]
【発明が解決しようとする課題】近年、携帯電話やノー
トパソコンなど携帯型の機器が急増しているが、これら
携帯型機器では保護対象の回路側の接地が電気的に浮い
た状態になるため、人体などから放電されたＥＳＤエネ
ルギーの帰還経路がなくなり、十分な過渡電圧吸収機能
を発揮することができないとう問題も発生している。す
なわち、据え置き型の機器であれば、図１に示すように
過渡電圧保護素子の接地は、大地に接地されていたり、
放電側（過渡電圧発生側）の接地とつながっているた
め、回路側から放電側へ帰還する経路ができ十分な保護
機能を期待できるが、携帯型の機器になると、図２に示
すように、回路及び保護素子の接地が電気的に浮いた状
態になることから放電側への帰還経路がなくなり、過渡
電圧保護素子により吸収されたエネルギーが回路側の低
電位（接地端子など）へ一気に流れ込んでしまう。これ
により大きな電位差が発生して回路素子の破壊を招いて
しまう結果となる。In recent years, the number of portable devices such as mobile phones and notebook computers has increased rapidly. However, in these portable devices, the ground on the circuit side to be protected becomes electrically floating. However, there is also a problem that the ESD energy discharged from the human body does not have a return path and the transient voltage absorbing function cannot be sufficiently exerted. That is, in the case of a stationary device, as shown in FIG. 1, the transient voltage protection element is grounded to the ground,
Since it is connected to the ground on the discharge side (transient voltage generation side), a route to return from the circuit side to the discharge side can be provided, and a sufficient protection function can be expected, but when it is a portable device, as shown in FIG. Since the ground of the circuit and the protection element is in an electrically floating state, there is no return path to the discharge side, and the energy absorbed by the transient voltage protection element flows into the low potential (ground terminal, etc.) of the circuit all at once. I will end up. As a result, a large potential difference is generated, resulting in destruction of the circuit element.
【０００４】また、ＩＣの高集積化でゲート絶縁膜など
半導体素子の絶縁壁が薄くなっており、過渡電圧に対し
てますます弱くなってきている。そのため最近では、過
渡電圧保護素子を設けているにもかかわらず、保護でき
ない場合も出てきている。その原因は、過渡電圧が生じ
てから過渡電圧保護素子が動作し始めるまでのタイムラ
グにあり、そのタイムラグの間に瞬間的にかかる高電圧
が、薄くなった絶縁壁を破壊してしまうものである。Further, as the IC is highly integrated, the insulating wall of a semiconductor element such as a gate insulating film is thinned, and it is becoming weaker against a transient voltage. Therefore, in recent years, there have been cases where protection is not possible despite the provision of a transient voltage protection element. The cause is the time lag between the occurrence of the transient voltage and the start of operation of the transient voltage protection device, and the high voltage applied instantaneously during the time lag destroys the thinned insulating wall. .
【０００５】以上の課題に着目して本発明では、より性
能のよい保護用の回路構成を提供するものである。Focusing on the above problems, the present invention provides a protection circuit configuration with better performance.
【０００６】[0006]
【課題を解決するための手段】本発明によれば、まず、
保護対象の回路の端子に一方の端子を接続し且つ他方の
端子を接地した過渡電圧保護素子を備えるとともに、該
過渡電圧保護素子の他方の端子と前記回路の接地端との
間に所定のダム用容量を設定した過渡電圧吸収用回路を
提供する。この容量がいわばエネルギーのダムとして働
き、過渡電圧保護素子により吸収されたエネルギー（電
流）を一時的に蓄えた後に、徐々に放電させることがで
きる。したがって、接地が電気的に浮いた状態であって
も、吸収エネルギーが一気に流れ込んで高電位をもたら
す現象は回避することができる。According to the present invention, first of all,
A transient voltage protection device in which one terminal is connected to the terminal of the circuit to be protected and the other terminal is grounded is provided, and a predetermined dam is provided between the other terminal of the transient voltage protection device and the ground terminal of the circuit. Provided is a transient voltage absorption circuit in which a capacitance for setting is set. This capacitance acts as an energy dam, so that the energy (current) absorbed by the transient voltage protection element can be temporarily stored and then gradually discharged. Therefore, even when the ground is in an electrically floating state, it is possible to avoid a phenomenon in which absorbed energy flows into the ground all at once and causes a high potential.
【０００７】さらに本発明によれば、保護対象の回路の
端子に一方の端子を接続し且つ他方の端子を接地した過
渡電圧保護素子を備えるとともに、該過渡電圧保護素子
の一方の端子と前記回路の端子との間に所定の抵抗値を
設定し、該抵抗値により、放電側から放電されたＥＳＤ
エネルギーをせき止めて前記過渡電圧保護素子へかかる
電圧を押し上げるようにした過渡電圧吸収用回路を提供
する。その所定の抵抗値は、保護対象の回路の端子にお
ける信号に影響を及ぼさないレベルとする。この抵抗値
は、電圧降下機能をもつのではなく、瞬間的（高周波
的）に過渡電圧保護素子に対する電圧を押し上げる働き
の制限抵抗としての機能をもち、過渡電圧保護素子の動
作開始を高速化させる。Further, according to the present invention, a transient voltage protection element having one terminal connected to the terminal of the circuit to be protected and the other terminal grounded is provided, and one terminal of the transient voltage protection element and the circuit are provided. A predetermined resistance value is set between this terminal and the terminal, and the ESD value is discharged from the discharge side by the resistance value.
Provided is a transient voltage absorption circuit that blocks energy and boosts the voltage applied to the transient voltage protection element. The predetermined resistance value is set to a level that does not affect the signal at the terminal of the circuit to be protected. This resistance value does not have a voltage drop function, but has a function as a limiting resistance for momentarily (high-frequency) increasing the voltage to the transient voltage protection element, and speeds up the operation start of the transient voltage protection element. .
【０００８】そして、これらの容量及び抵抗値は両方と
も備えるようにしておくと、吸収エネルギーのダム機能
と過渡電圧保護素子の動作高速化（タイムラグの抑制）
機能の両方を一度に得られるので、好ましい。If both of these capacitances and resistance values are provided, the dam function of absorbed energy and the operation speed of the transient voltage protection element are accelerated (time lag is suppressed).
It is preferable because both functions can be obtained at one time.
【０００９】[0009]
【発明の実施の形態】図３に、ＩＣ（保護対象の回路）
の入力端子と接地との間に過渡電圧保護素子を設け、さ
らに、その過渡電圧保護素子の接地とＩＣの接地（comm
onGND）との間にダム用の容量を設けた過渡電圧吸収用
回路の例を示す。図示のＩＣは携帯型機器に入れられて
いるもので、接地が電気的に浮いた状態にある。DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows an IC (circuit to be protected).
The transient voltage protection element is provided between the input terminal of the
An example of a transient voltage absorption circuit in which a dam capacitor is provided between the on GND) and the The illustrated IC is placed in a portable device, and the ground is in an electrically floating state.
【００１０】本例のダム用容量のキャパシタンスは、放
電側容量及び電圧の積を、ダム用容量に設定される電圧
で除した値以上としている。たとえば、IEC61000-4-2で
規定される人体モデルの場合、容量１５０ｐＦ及び電圧
８ｋＶなので、ダム用容量に設定される電圧を５Ｖとす
れば、０．２４μＦ以上とする。The capacitance of the dam capacitor of this example is equal to or greater than the product of the discharge-side capacitance and the voltage divided by the voltage set for the dam capacitor. For example, in the case of the human body model defined by IEC61000-4-2, the capacity is 150 pF and the voltage is 8 kV, so if the voltage set for the dam capacity is 5 V, it is 0.24 μF or more.
【００１１】ＩＣの入力、出力インピーダンスは過渡電
圧保護素子の動作状態における数Ωに比べて極端に高い
ので、本例のようにダム用容量を設けると、放電側から
発生して過渡電圧保護素子により吸収されたエネルギー
は確実にダム用容量へ流れ込むことになる。その吸収エ
ネルギーは、ダム用容量で一時的に蓄えられた後、徐々
に放電されていく。Since the input and output impedances of the IC are extremely higher than several Ω in the operating state of the transient voltage protection element, if a dam capacitor is provided as in this example, the transient voltage protection element is generated from the discharge side. The energy absorbed by will certainly flow into the dam capacity. The absorbed energy is temporarily stored in the dam capacity and then gradually discharged.
【００１２】図４には、上記のダム用容量に加えて、過
渡電圧保護素子とＩＣの入力端子との間に抵抗値として
抵抗素子を設けた制限抵抗付きの例を示す。この抵抗素
子は高周波的に働くため、インダクタンス成分を含むも
のとする。FIG. 4 shows an example with a limiting resistor in which a resistance element is provided as a resistance value between the transient voltage protection element and the input terminal of the IC in addition to the dam capacitance. Since this resistance element works at high frequencies, it is assumed that it contains an inductance component.
【００１３】このように制限抵抗を設定することによ
り、放電側から放電されたＥＳＤエネルギーが制限抵抗
により一旦せき止められる状態となるので、過渡電圧保
護素子へかかる電圧が押し上げられるかたちとなり、よ
り高速に過渡電圧保護素子を動作開始させることができ
る。このせき止め状態を得る働きのため、制限抵抗は過
渡電圧保護素子へできるだけ近づけて配置するのがよ
い。By setting the limiting resistance in this way, the ESD energy discharged from the discharge side is temporarily stopped by the limiting resistance, so that the voltage applied to the transient voltage protection element is pushed up and the speed is further increased. The transient voltage protection device can be activated. Due to the effect of obtaining this dampening state, it is desirable to place the limiting resistor as close as possible to the transient voltage protection element.
【００１４】[0014]
【発明の効果】本発明の過渡電圧吸収用回路によれば、
保護対象の回路の接地と過渡電圧保護素子の接地との間
に所定の容量を設定することにより、回路の接地へ流れ
込む吸収エネルギーを一時的に蓄えてから徐々に放電さ
せられるので、高電位の発生を抑止することができ、保
護機能を高めることができる。また、保護対象の回路の
端子と過渡電圧保護素子との間に所定の抵抗値を設定す
ることにより、過渡電圧のエネルギーをせき止めて過渡
電圧保護素子へ集中させられるので、過渡電圧保護素子
の動作高速化を図れ、保護機能を高めることができる。
そして、これらを併用することで、いっそう効果の高い
過渡電圧吸収用回路が提供される。According to the transient voltage absorbing circuit of the present invention,
By setting a predetermined capacity between the ground of the circuit to be protected and the ground of the transient voltage protection element, the absorbed energy flowing into the ground of the circuit can be temporarily stored and then gradually discharged, so that a high potential The occurrence can be suppressed and the protection function can be enhanced. Also, by setting a predetermined resistance value between the terminal of the circuit to be protected and the transient voltage protection element, the energy of the transient voltage can be blocked and concentrated in the transient voltage protection element. The speed can be increased and the protection function can be enhanced.
Then, by using these together, a transient voltage absorbing circuit having a higher effect is provided.
【図１】過渡電圧保護素子の従来例を示す回路図。FIG. 1 is a circuit diagram showing a conventional example of a transient voltage protection device.
【図２】携帯型機器における過渡電圧保護素子の従来例
を示す回路図。FIG. 2 is a circuit diagram showing a conventional example of a transient voltage protection element in a portable device.
【図３】本発明による過渡電圧吸収用回路の一例を示す
回路図。FIG. 3 is a circuit diagram showing an example of a transient voltage absorbing circuit according to the present invention.
【図４】本発明による過渡電圧吸収用回路の他の例を示
す回路図。FIG. 4 is a circuit diagram showing another example of a transient voltage absorbing circuit according to the present invention.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平10−173134（ＪＰ，Ａ) 特開 平11−289053（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) H01L 21/822 H01L 27/04 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-10-173134 (JP, A) JP-A-11-289053 (JP, A) (58) Fields investigated (Int.Cl. 7 , DB name) H01L 21/822 H01L 27/04
Claims (3)
続し且つ他方の端子を接地した過渡電圧保護素子を備え
るとともに、該過渡電圧保護素子の他方の端子と前記回
路の接地端との間に所定のダム用容量を設定した過渡電
圧吸収用回路。1. A transient voltage protection device, in which one terminal is connected to a terminal of a circuit to be protected and the other terminal is grounded, and the other terminal of the transient voltage protection device and the ground terminal of the circuit are provided. A transient voltage absorption circuit with a specified dam capacity set between them.
続し且つ他方の端子を接地した過渡電圧保護素子を備え
るとともに、該過渡電圧保護素子の一方の端子と前記回
路の端子との間に所定の抵抗値を設定し、該抵抗値によ
り、放電側から放電されたＥＳＤエネルギーをせき止め
て前記過渡電圧保護素子へかかる電圧を押し上げるよう
にした過渡電圧吸収用回路。2. A transient voltage protection element having one terminal connected to a terminal of a circuit to be protected and the other terminal grounded, and between the one terminal of the transient voltage protection element and the terminal of the circuit. A circuit for absorbing transient voltage, in which a predetermined resistance value is set, and the ESD energy discharged from the discharge side is blocked by the resistance value to boost the voltage applied to the transient voltage protection element.
続し且つ他方の端子を接地した過渡電圧保護素子を備え
るとともに、該過渡電圧保護素子の一方の端子と前記回
路の端子との間に所定の抵抗値を設定し、該抵抗値によ
り、放電側から放電されたＥＳＤエネルギーをせき止め
て前記過渡電圧保護素子へかかる電圧を押し上げるよう
にし、さらに、前記過渡電圧保護素子の他方の端子と前
記回路の接地端との間に所定のダム用容量を設定した過
渡電圧吸収用回路。3. A transient voltage protection element having one terminal connected to the terminal of the circuit to be protected and the other terminal grounded, and between the one terminal of the transient voltage protection element and the terminal of the circuit. Is set to a predetermined resistance value to prevent the ESD energy discharged from the discharge side by the resistance value to push up the voltage applied to the transient voltage protection element, and further to the other terminal of the transient voltage protection element. A transient voltage absorbing circuit in which a predetermined dam capacitance is set between the circuit and the ground terminal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000071132A JP3414690B2 (en) | 2000-03-14 | 2000-03-14 | Circuit for transient voltage absorption |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000071132A JP3414690B2 (en) | 2000-03-14 | 2000-03-14 | Circuit for transient voltage absorption |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001267494A JP2001267494A (en) | 2001-09-28 |
| JP3414690B2 true JP3414690B2 (en) | 2003-06-09 |
Family
ID=18589757
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000071132A Expired - Fee Related JP3414690B2 (en) | 2000-03-14 | 2000-03-14 | Circuit for transient voltage absorption |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3414690B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2016219716A (en) * | 2015-05-26 | 2016-12-22 | 住友ベークライト株式会社 | Transient voltage protection element, resin composition and protective member |
-
2000
- 2000-03-14 JP JP2000071132A patent/JP3414690B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2001267494A (en) | 2001-09-28 |
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