JP4380031B2

JP4380031B2 - Ignition semiconductor device

Info

Publication number: JP4380031B2
Application number: JP2000210910A
Authority: JP
Inventors: 昌一古畑; 実西尾
Original assignee: Fuji Electric Device Technology Co Ltd
Current assignee: Fuji Electric Co Ltd
Priority date: 1999-08-20
Filing date: 2000-07-12
Publication date: 2009-12-09
Anticipated expiration: 2020-07-12
Also published as: JP2002004991A

Description

【０００１】
【発明の属する技術分野】
本発明は点火用半導体装置に関し、特に自動車用内燃機関の点火装置系に適用される点火用半導体装置に関する。
【０００２】
【従来の技術】
自動車用内燃機関の点火装置系は、内燃機関の気筒ごとに点火コイルおよび点火用半導体装置を取り付けるようにしたディストリビュータレス点火システムが一般的になってきている。このようなシステムで使われる点火用半導体装置は、点火コイルの１次側電流をオン・オフさせるスイッチングデバイスから構成されている。
【０００３】
各気筒に設けられた点火用半導体装置は、エンジンコントロールユニットによって個々にオン・オフ制御されるが、たとえばエンジンがエンストした場合のように、そのオン・オフ制御が正常に行われなくなる場合がある。特に、スイッチングデバイスに連続した駆動信号が印加されるような場合には、１次側に連続電流が流れることにより点火コイルが破壊または焼損したり、特定の気筒だけが勝手に爆発することによってエンジンが異常振動したりするようになる。
【０００４】
このような異常動作に対処した装置が、たとえば特開平８−２８４１５号公報に記載されている。この公報に記載の技術によれば、連続通電防止回路を備え、エンジンコントロールユニットからの駆動信号によりスイッチングデバイスの通電状態が所定時間以上続いた場合に、そのスイッチングデバイスに入力される駆動信号を強制的に遮断してスイッチングデバイスの駆動を停止させるようにしている。これにより、連続通電によるスイッチングデバイスおよび点火コイルの損傷を防止している。
【０００５】
また、このような点火用半導体装置には、電流制限回路が設けられていて、スイッチングデバイスが過電流を検出した場合に、スイッチングデバイスの駆動信号を抑えることで、スイッチングデバイスが破壊されないようにすることも行われている。
【０００６】
【発明が解決しようとする課題】
しかしながら、従来の点火用半導体装置では、電流制限回路が出力段素子の過電流を防止して点火用半導体装置および点火コイルが熱破壊することを防止し、さらに連続通電防止回路が一定時間以上の連続した駆動信号が印加された場合にその駆動信号をオフさせて点火用半導体装置の出力段素子をオフ動作させているが、特に、一定時間経過後のオフ動作は通常時と同一速度で行っているため、点火コイルの２次巻線に通常動作時と同様の高圧電圧が発生し、気筒内に残っているガソリン混合気が着火してエンジンに異常な回転力を与えてしまうことがあるという問題点があった。
【０００７】
本発明はこのような点に鑑みてなされたものであり、駆動信号が連続して印加後に出力段素子をオフ動作させるが、そのオフ動作時に点火コイルの２次巻線に無用な高圧電圧を発生することがないようにした点火用半導体装置を提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明では上記問題を解決するために、点火コイルと直列に接続されて前記点火コイルに流れる電流をオン・オフ制御するスイッチングデバイスと、前記点火コイルに流れる電流を制限するよう前記スイッチングデバイスを制御する電流制限回路と、前記点火コイルから放出される電圧をクランプする電圧制限回路とを搭載した点火用半導体装置において、前記スイッチングデバイスの駆動端子に印加された入力信号に応答して動作を開始し、前記入力信号の印加から一定時間経過後に出力信号を出力するタイマ回路と、前記タイマ回路の出力信号に応答して、前記入力信号の継続印加に拘らず、前記スイッチングデバイスに流れている電流を低減させる主電流漸減回路と、を備え、前記電流制限回路は、前記スイッチングデバイスと直列に接続されて前記スイッチングデバイスに流れている電流に比例した電圧値を検出するシャント抵抗と、電流制限値に対応した基準電圧値を生成する基準電圧回路と、前記シャント抵抗の電圧値と前記基準電圧値とを入力とする演算増幅器と、前記演算増幅器の出力によって前記スイッチングデバイスの駆動端子に印加される入力信号の電圧を制御する第１のトランジスタとを有し、前記主電流漸減回路は、前記基準電圧回路に並列に接続されたコンデンサと、前記タイマ回路の出力信号に応答してターンオンする第２のトランジスタと、前記コンデンサおよび前記第２のトランジスタと直列に接続されて前記第２のトランジスタのターンオン時に前記コンデンサの電荷を放電させて前記基準電圧値を漸減させる抵抗とを有し、前記タイマ回路の出力信号に応答して前記基準電圧値を漸減させることにより前記スイッチングデバイスをターンオフ動作させることを特徴とする点火用半導体装置が提供される。
【０００９】
このような点火用半導体装置によれば、スイッチングデバイスをオン駆動する入力信号が連続して印加されるような場合、タイマ回路が出力信号を出力し、この出力信号に応答して、主電流漸減回路がスイッチングデバイスに流れている電流を低減させるように制御する。これにより、スイッチングデバイスは通常のオフ動作よりも低速度でオフ動作を行うことにより、点火コイルの１次巻線を流れる電流が低速度で遮断され、したがって、２次巻線に高圧電圧が発生することが抑制される。
【００１０】
【発明の実施の形態】
以下、本発明の実施の形態を図面を参照して詳細に説明する。
図１は本発明による点火用半導体装置の第１の実施の形態における構成例を示す回路図である。この点火用半導体装置１は、出力段素子であるスイッチングデバイスとしてＩＧＢＴ（Insulated Gate Bipolar Transistor：絶縁ゲート型バイポーラトランジスタ）２を使用している。ＩＧＢＴ２のコレクタとゲートとの間には、点火コイルから放出された電圧をクランプするためのツェナーダイオード３が接続されている。ＩＧＢＴ２のエミッタは、シャント抵抗４を介して接地され、ゲートは抵抗５，６を介して入力端子７に接続されている。ＩＧＢＴ２のエミッタとシャント抵抗４との接続点は演算増幅器８の非反転入力に接続され、演算増幅器８の反転入力は抵抗９，１０、コンデンサ１１および定電流素子１２の共通接続点に接続され、演算増幅器８の出力はＦＥＴ（Field-Effect Transistor：電界効果トランジスタ）１３のゲートに接続されている。このＦＥＴ１３のドレインは抵抗５，６の共通接続点に接続され、ソースは接地されている。入力端子７は、また、演算増幅器８の電源端子、定電流素子１２およびタイマ回路１４に接続されている。タイマ回路１４の出力はＦＥＴ１５のゲートに接続されている。このＦＥＴ１５のドレインは抵抗１０に接続され、ソースは接地されている。さらに、ＩＧＢＴ２のコレクタは、点火コイル１６の１次巻線に接続され、この１次巻線の他端は電池１７に接続されている。点火コイル１６の２次巻線は点火プラグのギャップ１８を介して接地されている。
【００１１】
ここで、シャント抵抗４、演算増幅器８、ＦＥＴ１３、抵抗５、抵抗９、定電流素子１２、および抵抗６は、ＩＧＢＴ２の負荷電流を制限するための電流制限回路を構成している。また、定電流素子１２は、演算増幅器８の基準電圧を作る目的の素子であり、その基準電圧は定電流素子１２が流す電流と抵抗９の抵抗値との積で定まる値であり、ＩＧＢＴ２の制限電流値がシャント抵抗４に流れたときの端子電圧に相当する。
【００１２】
さらに、抵抗９に並列に接続されたコンデンサ１１、抵抗１０、ＦＥＴ１５およびタイマ回路１４は、入力信号１９が連続して入力端子７に印加された場合にＩＧＢＴ２をオフ動作させるセルフシャットダウン回路を構成しているが、特に本発明では、このセルフシャットダウン回路は、ＩＧＢＴ２のターンオフ動作を低速で行う主電流漸減回路としている。タイマ回路１４は、入力信号１９が印加されたときからある一定時間経過後にＦＥＴ１５のゲートに駆動信号を出す回路である。
【００１３】
以上の構成において、入力信号１９が入力端子７に印加されると、ＩＧＢＴ２がターンオン動作をし、電池１７から点火コイル１６の１次巻線およびＩＧＢＴ２を介して電流が流れる。その後、タイマ回路１４の動作時間より短い時間範囲内で入力信号１９がオフになると、ＩＧＢＴ２はターンオフ動作をし、点火コイル１６の１次巻線に流れていた電流が遮断される。これにより、点火コイル１６の１次巻線に蓄えられたエネルギが２次巻線に誘起され、２次巻線に高圧電圧が発生してギャップ１８にて放電が発生し、気筒内の混合気に点火される。この通常動作でのＩＧＢＴ２のターンオフ動作は、ＩＧＢＴ２の入力容量と抵抗５，６および入力信号回路の抵抗値で決定され、一般に、５０マイクロ秒以下で動作する。
【００１４】
入力端子７に入力信号１９が印加されたとき、入力信号１９の電位が演算増幅器８の電源電圧になるとともに、定電流素子１２により抵抗９に一定の電流を供給し、演算増幅器８の反転入力に基準電圧を与える。これにより、この点火用半導体装置１の電流制限回路が動作する。ＩＧＢＴ２がターンオン動作することにより、シャント抵抗４に電流が流れるが、この電流が異常に増えて、シャント抵抗４の端子電圧が基準電圧を越えると、演算増幅器８の出力電位が反転し、ＦＥＴ１３をターンオンし、抵抗５，６の共通接続点をアースに接続することにより、ＩＧＢＴ２のゲートへの入力信号１９を遮断し、ＩＧＢＴ２を強制的にターンオフ動作させる。
【００１５】
次に、エンストなどにより、入力端子７に入力信号１９が連続して印加されるときのこの点火用半導体装置の動作を図２を参照しながら説明する。
図２は点火コイルの２次側電圧と１次側電流・電圧の関係を示す図であって、（Ａ）は点火コイル周りを示し、（Ｂ）は点火コイルの１次側電流・電圧の変化を示し、（Ｃ）は点火コイルの２次側電圧の変化を示している。図２の（Ａ）において、ＩＧＢＴ２はスイッチで表し、点火コイル１６の１次巻線を流れる電流をＩ_L、ＩＧＢＴ２のコレクタ・エミッタ間電圧をＶ_SW、２次巻線に発生されるギャップ１８の電圧をＶ_C2で表している。
【００１６】
まず、点火用半導体装置１の通常動作から説明する。ＩＧＢＴ２がターンオンすると、（Ｂ）に示したように、電圧Ｖ_SWは電池の電圧から接地電位に低下し、点火コイル１６の１次巻線を流れる電流Ｉ_Lは徐々に上昇する。その後、電流Ｉ_Lが所定の電流値以上になると、電流制限回路が動作し、電流値が制限され、電圧Ｖ_SWが若干上昇する。ＩＧＢＴ２がターンオフ動作をすると、電流Ｉ_Lは０まで低下し、これに伴って、電圧Ｖ_SWが急上昇する。この電圧Ｖ_SWは、ツェナーダイオード３によって決まるツェナー電圧でクランプされると、１次巻線のエネルギが２次巻線側に誘起し、その後低下する。２次巻線側は、その誘起されたエネルギによって、マイナスの電位が生起し、（Ｃ）に示したように、ギャップ１８の電圧Ｖ_C2がマイナス方向に上昇していく。この２次巻線に生起された電圧は、ある位相遅れをもって１次巻線側に帰還され、低下していた電圧Ｖ_SWは再度上昇する。そして、２次巻線の電圧、すなわちギャップ１８の電圧Ｖ_C2がある電圧まで上昇すると、ギャップ１８にて放電が発生し、これにより、点火コイル１６の１次巻線および２次巻線の電圧は低下し、電圧Ｖ_SWは電池電圧に、ギャップ１８の電圧Ｖ_C2は０になる。
【００１７】
次に、エンストが発生して、入力信号１９が連続して印加される場合について説明する。入力信号１９の印加が一定時間以上経過すると、タイマ回路１４がＦＥＴ１５のゲートに駆動信号を出す。すると、ＦＥＴ１５はターンオンし、コンデンサ１１に蓄えられた電荷を抵抗１０を介して放電する。この放電する速度はこれらコンデンサ１１および抵抗１０の時定数によって決められる。
【００１８】
タイマ回路１４がＦＥＴ１５に対して駆動信号を出すとき、ＩＧＢＴ２は演算増幅器８、ＦＥＴ１３などにより電流制限が掛かっている状態にある。この状態のときに、コンデンサ１１が放電されると、演算増幅器８の基準電圧が徐々に低下していくことになる。ＩＧＢＴ２は、シャント抵抗４の端子電圧と演算増幅器８の基準電圧とが同じになるよう電流制御するので、図２の（Ｂ）に破線で示したように、基準電圧の低下に伴って徐々に電流Ｉ_Lを減少させていく。これにより、電圧Ｖ_SWについても、破線で示したように、電流制限されているときの電位から徐々に上昇するようになり、これに伴って、ギャップ１８の電圧Ｖ_C2は、図２の（Ｃ）に破線で示したように変化することになる。このように、ＩＧＢＴ２の電流制限値を変化させてＩＧＢＴ２を低速でターンオフ動作させるようにしたことで、ギャップ１８の電圧Ｖ_C2は放電に至る電圧まで昇圧されることがなくなり、したがって、無用な爆発が起きることもなくなる。
【００１９】
以上の、ＩＧＢＴ２の負荷電流を制限するための電流制限回路およびＩＧＢＴ２のターンオフ動作を低速で行う主電流漸減回路を備えた点火用半導体装置１はそれらの各部品を組み合わせた混成集積回路によって構成することができる。たとえばセラミック基板上に、ＩＧＢＴ２、演算増幅器８、定電流素子１２、タイマ回路１４、ＦＥＴ１３，１５などのシリコンチップを搭載し、抵抗５，６，９，１０として印刷抵抗または抵抗チップを、シャント抵抗４として抵抗チップを、コンデンサ１１としてコンデンサチップを搭載し、それらをワイヤで接続し、樹脂封止することによって１パッケージに納めることができる。
【００２０】
また、点火用半導体装置１は、ＩＧＢＴ２、電流制限回路および主電流漸減回路の複数の半導体チップ（ベアチップ）のみで構成して１パッケージに納めるようにすることもできる。
【００２１】
さらに、点火用半導体装置１のすべての機能を一つのシリコン基板上に形成することにより、点火用半導体装置１を１チップにて構成することもできる。
図３は点火用半導体装置の第２の実施の形態における構成例を示す回路図である。この図３において、図１に示した要素と同じ要素については同じ符号を付してその詳細な説明は省略する。本実施の形態では、主電流漸減回路を、タイマ回路１４と、発振回路２０と、シフト回路２１と、ｎ組の抵抗２２−１〜２２−ｎおよびＦＥＴ２３−１〜２３−ｎとで構成している。
【００２２】
タイマ回路１４は、入力信号１９が印加されたときからある一定時間経過後に主電流漸減開始信号を出す回路であり、その出力は発振回路２０に接続される。発振回路２０の出力はシフト回路２１に接続され、シフト回路２１のｎ個の出力はそれぞれＦＥＴ２３−１〜２３−ｎのゲートに接続されている。抵抗２２−１〜２２−ｎおよびＦＥＴ２３−１〜２３−ｎの各直列回路は、演算増幅器８の基準電圧を生成する抵抗９にそれぞれ並列に接続されている。この抵抗９と抵抗２２−１〜２２−ｎとの並列回路により、演算増幅器８の基準電圧を階段状に低減させる回路を構成している。
【００２３】
発振回路２０は、階段状に低減させる速度を決め、シフト回路２１は、ＦＥＴ２３−１、ＦＥＴ２３−ｎあるいはＦＥＴ２３−１とＦＥＴ２３−ｎとの中間に存在するＦＥＴの、どのＦＥＴを駆動するかを決める回路である。抵抗２２−１〜２２−ｎが同一抵抗値の場合には、１番目のＦＥＴ２３−１からｎ番目のＦＥＴ２３−ｎまで、順番に駆動信号を与えれば、抵抗９の両端低抗値は、抵抗９とｎ個の抵抗値の並列値になり、徐々に抵抗値が下がる。そして抵抗９の両端電圧はオームの法則（抵抗×電流＝電圧）で決まる電圧になり、結果としてＩＧＢＴ２のコレクタ電流をゆっくり減少させることができる。それが、点火コイル１６の２次巻線に高圧電圧が発生するのを抑制することにつながる。
【００２４】
図４は点火用半導体装置の第３の実施の形態における構成例を示す回路図である。この図４において、図１に示した要素と同じ要素については同じ符号を付してその詳細な説明は省略する。本実施の形態では、電流制限回路を、抵抗２４，２５とトランジスタ２６とで構成し、主電流漸減回路を、タイマ回路１４と、抵抗２７と、ＦＥＴ２８とで構成している。
【００２５】
すなわち、電流制限回路では、ＩＧＢＴ２のエミッタとシャント抵抗４との接続点は抵抗２４を介してトランジスタ２６のベースに接続され、トランジスタ２６のコレクタは抵抗５と抵抗６との共通接続点に接続され、エミッタは抵抗２５を介して接地されている。主電流漸減回路では、タイマ回路１４の出力はＦＥＴ２８のゲートに接続され、ドレインは抵抗５と抵抗６との共通接続点に接続され、ソースは接地されている。
【００２６】
入力端子７への入力信号１９の印加によってＩＧＢＴ２がターンオンし、主電流が増加していく途中で、主電流によって生じるシャント抵抗４の端子電圧がトランジスタ２６の順方向バイアス電圧を越えると、トランジスタ２６がターンオンし、抵抗５と抵抗６との共通接続点の電位をアース電位の方向に引き込み、ＩＧＢＴ２のゲート電圧を低下させることにより、主電流を低下させ、主電流を予め決められた値に制限する。
【００２７】
次に、入力信号１９が連続して入力端子７に印加された場合は、入力信号１９の印加時点から所定時間後にタイマ回路１４が駆動信号を出力する。これにより、ＦＥＴ２８がターンオンし、入力信号１９が抵抗２７に分流してＩＧＢＴ２のゲート電圧を下げようとする。また、ＩＧＢＴ２のゲートに蓄えられた電荷は抵抗５および抵抗２７を介し放出され、ＩＧＢＴ２はオフ動作を開始する。ＩＧＢＴ２のターンオフ速度を決めるのは抵抗５および抵抗２７であり、抵抗２７の抵抗値を大きくすることでＩＧＢＴ２のターンオフ速度を遅くすることができる。すなわち、ＩＧＢＴ２および点火コイル１６の１次巻線を流れる電流をゆっくり低減させることができ、点火コイル１６の２次巻線に高圧電圧が発生するのを抑制することができる。
【００２８】
図５は点火用半導体装置の第４の実施の形態における構成例を示す回路図である。この図５において、図１に示した要素と同じ要素については同じ符号を付してその詳細な説明は省略する。本実施の形態では、主電流漸減回路を、定電流素子１２と、抵抗９と、ダイオード３５と、コンデンサ１１と、タイマ回路１４と、ＦＥＴ３１，３２，３３とで構成している。
【００２９】
すなわち、主電流漸減回路において、コンデンサ１１は、定電流素子１２から抵抗９へ流れる電流の一部がダイオード３５を介して充電するように接続され、また、定電流放電するように、ＦＥＴ３２のドレインに接続されている。このＦＥＴ３２のソースは接地され、ゲートはＦＥＴ３３のゲートおよびドレインに接続され、このＦＥＴ３３のドレインは定電流素子３４に接続され、ソースは接地されている。これらＦＥＴ３２，３３はカレントミラー回路を構成し、コンデンサ１１は定電流素子３４によって決まる電流で定電流放電することになる。タイマ回路１４の出力はＦＥＴ３１のゲートに接続され、ドレインは抵抗５とダイオード３５との共通接続点に接続され、ソースは接地されている。
【００３０】
入力端子７への入力信号１９の印加によってＩＧＢＴ２がターンオンし、主電流が増加していく途中で、主電流によって生じるシャント抵抗４の端子電圧が定電流素子１２と抵抗９とによって決まる基準電圧を越えると、ＦＥＴ１３がターンオンし、抵抗５と抵抗６との共通接続点の電位をアース電位の方向に引き込み、ＩＧＢＴ２のゲート電圧を低下させることにより、主電流を低下させ、主電流を予め決められた値に制限する。
【００３１】
次に、入力信号１９が連続して入力端子７に印加された場合は、入力信号１９の印加時点から所定時間後にタイマ回路１４が駆動信号を出力し、ＦＥＴ３１をターンオンし、ダイオード３５のアノードをアース電位にする。このとき、ダイオード３５は、コンデンサ１１へ充電しないようにするとともにコンデンサ１１の放電電流が、抵抗９とＦＥＴ３１に流れ込まないようにする。これにより、ＦＥＴ３２はコンデンサ１１に蓄えられた電荷を定電流放電する。
【００３２】
タイマ回路１４がＦＥＴ３１に対して駆動信号を出すとき、ＩＧＢＴ２は演算増幅器８，ＦＥＴ１３などにより電流制限がかかっている状態にある。この状態のときにコンデンサ１１が放電されると、ＦＥＴ３２には、定電流素子３４で決まる定電流が流れるＦＥＴ３３とＦＥＴ３２との比で決まる定電流が流れるため、コンデンサ１１は徐々に放電され、演算増幅器８の基準電圧が徐々に低下していくことになる。これにより、ＩＧＢＴ２および点火コイル１６の１次巻線を流れる電流はゆっくり低減されることになり、点火コイル１６の２次巻線に高圧電圧を発生することが抑制される。
【００３３】
ところで、一般の自動車の電池電圧は１２Ｖ仕様であるが、寒冷地などにおいて電池を２個直列にして始動したり、あるいは夏場であっても電池が劣化し、再始動できない状況下で他の車の電源を利用してエンジン始動する場合がある。当然、１２Ｖ車が電池電圧２４Ｖ車の電源を利用するケースがある。このようなケースにおいて、入力信号１９が連続して入力端子７に印加される場合が発生すると、電流制限動作時にスイッチングデバイスであるＩＧＢＴ２に印加される電圧が多大になり、ＩＧＢＴ２が熱破壊することがあり得る。
【００３４】
たとえば電池電圧１２Ｖ、電流制限値２０Ａ、点火コイル抵抗０．５Ωの場合、ＩＧＢＴ２のコレクタ損失は、２０Ａ×（１２Ｖ−２０Ａ×０．５Ω）＝４０Ｗになる。一方、電池電圧１２Ｖ、電流制限値２０Ａ、点火コイル抵抗０．５Ωの回路に２４Ｖの電源を利用した場合には、２０Ａ×（２４Ｖ−２０Ａ×０．５Ω）＝２８０Ｗにもなってしまう。
【００３５】
そこで、電源電圧が通常時より高い場合でもスイッチングデバイスのＩＧＢＴ２が熱破壊しないようにすることが必要である。次に、このような対策を施した点火用半導体装置について説明する。
【００３６】
図６は点火用半導体装置の第５の実施の形態における構成例を示す回路図である。この図６において、図１に示した要素と同じ要素については同じ符号を付してその詳細な説明は省略する。本実施の形態では、電流制限回路および主電流漸減回路を含む電流制限／主電流漸減回路４０に加え、電池１７の電圧が規定電圧以上であって、連続した入力信号１９がある場合に、ＩＧＢＴ２の主電流を高速に遮断する主電流遮断回路を備えている。
【００３７】
すなわち、主電流遮断回路は、ＩＧＢＴ２のコレクタ電圧を検出する分圧用の抵抗４１，４２と、規定電圧を設定する基準電圧源４３と、非反転入力が抵抗４１，４２の共通接続点に接続され、反転入力が基準電圧源４３に接続された演算増幅器４４と、この演算増幅器４４の出力に接続された抵抗４５と、ドレインがＩＧＢＴ２のゲートに直列に接続された２つの抵抗５ａ，５ｂの接続点に接続され、ソースが接地され、ゲートが抵抗４５を介して演算増幅器４４の出力に接続されたＦＥＴ４６とから構成されている。演算増幅器４４の電源端子は、入力端子７に接続されている。これにより、入力信号１９およびＩＧＢＴ２のコレクタ電圧をモニタし、コレクタ電圧が規定電圧以上のときに入力信号１９が連続して印加された場合、ＩＧＢＴ２のゲート電圧をＩＧＢＴ２がオン状態を持続できない駆動電圧に強制的に低減し、主電流を遮断する回路を構成している。
【００３８】
この構成において、入力信号１９が連続して印加された場合、電流制限／主電流漸減回路４０によりＩＧＢＴ２は一定の主電流を流した後、ゆるやかに主電流を低減させる動作を行う。この場合、電流制限動作時のＩＧＢＴ２のコレクタ電圧は、電池１７の電圧から点火コイル抵抗と電流制限値との積を差し引いた電圧、すなわち、Ｖ_CE＝Ｖ_B−Ｒｃ×Ｉｃｌが加わる。ここで、Ｖ_CEはＩＧＢＴ２のコレクタ・エミッタ間電圧、Ｖ_Bは電池電圧、Ｒｃは点火コイル抵抗、Ｉｃｌは電流制限値である。
【００３９】
この場合、電池電圧が高い場合でも電流制限値の増加は殆どないため、ＩＧＢＴ２のコレクタ電圧は、電池電圧の増加分増加することになる。
以上の構成によれば、まず、抵抗４１，４２および基準電圧源４３で決まるコレクタ電圧値で演算増幅器４４に出力が発生し、ＦＥＴ４６を駆動する。ＦＥＴ４６はＩＧＢＴ２のゲート・エミッタ間に並列に接続されているため、電流制限／主電流漸減回路４０の動作に拘らず、ＩＧＢＴ２のゲート電圧を強制的にグランドに落とし、ＩＧＢＴ２を高遠にターンオフ状態に移行させる働きをする。
【００４０】
なお、演算増幅器４４の非反転入力に加えるコレクタ電圧の分圧は、抵抗４１の代わりにツェナーダイオードとしてもよい。また、ツェナーダイオードと抵抗４１との直列構成でもよい。さらに、抵抗４１と直列に定電流素子を接続し、一定電圧以上のコレクタ電圧を定電流素子で分担させてもよい。
【００４１】
また、電流制限／主電流漸減回路４０として、図１、図４または図５に例示した電流制限回路および主電流漸減回路で構成することができる。
次に、上述のように、一般の自動車の電池電圧は１２Ｖ仕様であるが、寒冷地や電池劣化時などではエンジン始動時に電池電圧が降下することがある。このとき、スイッチングデバイスをオン・オフさせる入力信号１９は、通常電池電圧時に比べて長いオン時間に制御されて入力されることがある。したがって、異常に長い時間の入力信号１９が入力されたときの保護回路として動作する上述の主電流漸減回路は、通常電池電圧時に比べて長い時間に制御された入力信号に合せ、その時間を越えて継続して入力されたときに動作するよう構成すればよい。しかし、そのような構成にすると、逆に、電池電圧が高くなった場合には、スイッチングデバイスが熱破壊する可能性がでてくる。これを防止するには、電池電圧がある電圧以上になると、タイマ回路が主電流漸減回路を漸減動作開始させるための出力信号を出力するまでのタイムアウト時間を短くする必要がある。そのためには、電池電圧をスイッチングテバイスがモニタする必要がある。
【００４２】
一般的に、スイッチングデバイスの主電流回路の一方が負荷である点火コイル１６の１次巻線を介して電池に接続され、他方が接地されているような回路構成では、スイッチングデバイス自身で電池電圧を直接モニタすることはできない。このため、電池電圧をモニタしようとすると、電池から直接電圧信号を受け取るための端子がもう１本必要となる。以下では、このような追加の端子を必要とすることなく、電池電圧をモニタして、スイッチングデバイスの熱破壊を防止する機能を備えた点火用半導体装置について説明する。
【００４３】
図７は点火用半導体装置の第６の実施の形態における構成例を示す回路図である。この図７において、図１に示した要素と同じ要素については同じ符号を付してその詳細な説明は省略する。本実施の形態では、電池１７の電圧をモニタする回路として、ＩＧＢＴ２がターンオフ動作のときにそのコレクタ・エミッタ間にかかる電圧Ｖ_CEを検出して保持するオフ時Ｖ_CE電圧保持回路４７と、電池１７の電圧が高いかどうかを比較するための演算増幅器４８と、電圧比較のための基準電圧源４９とを備え、タイマ制御回路を構成している。なお、この図では、説明のため、主電流漸減回路を構成しているモニタ回路を独立させ、タイマ回路１４ａと電流制限／主電流漸減回路４０ａとで示している。
【００４４】
タイマ制御回路において、オフ時Ｖ_CE電圧保持回路４７は、ＩＧＢＴ２のコレクタに接続されてＩＧＢＴ２がターンオフ動作のときにコレクタに印加される電圧（＝電池１７の電圧）を入力し、電池１７の電圧をその変化に追従して記憶するようにし、ＩＧＢＴ２がターンオン動作する入力信号１９が入力端子７に印加されると、入力信号１９の印加直前に記憶された電圧値を保持し、出力するよう構成されている。ＩＧＢＴ２がターンオフ動作のときにそのコレクタ・エミッタ間電圧Ｖ_CEをモニタすることで、電池１７の電圧値を正確に検知することができる。演算増幅器４８は、ＩＧＢＴ２がターンオン動作する入力信号１９が入力端子７に印加されたとき動作し、非反転入力に印加されたオフ時Ｖ_CE電圧保持回路４７に保持されている電池１７の電圧と反転入力に印加された基準電圧源４９の電圧とを比較し、その比較結果をタイマ回路１４ａに供給する構成にしてある。タイマ回路１４ａは、入力信号１９が印加されてからある一定時間経過後に電流制限／主電流漸減回路４０ａに主電流漸減開始信号を出す回路であるが、演算増幅器４８から電池１７の電圧が高い状態を表す電圧比較結果を受けた場合は、たとえばその時定数を小さく切り換えて、入力信号１９の印加から主電流漸減開始信号を出力するまでの時間が短くなるように構成されている。
【００４５】
このような回路によれば、入力信号１９が入力端子７に印加される前では、オフ時Ｖ_CE電圧保持回路４７によって、入力信号１９の印加前のＶ_CE電圧、すなわち電池１７の電圧を保持し、入力信号１９が印加されると同時に演算増幅器４８が作動して、オフ時Ｖ_CE電圧保持回路４７によって保持されていたＶ_CE電圧と基準電圧源４９の電圧との比較の結果を出力し、タイマ回路１４ａに電圧比較結果信号が入力される。電圧比較結果信号が入力されたタイマ回路１４ａは、電圧比較結果信号に応じた時間で主電流漸減開始信号を出力する。すなわち、タイマ回路１４ａは、電圧比較の結果、電池１７の電圧が高い場合に、主電流漸減開始信号を短い時間で出力する。
【００４６】
図８は点火用半導体装置の第６の実施の形態における構成をより具体的に示した回路図である。
この図において、タイマ制御回路のオフ時Ｖ_CE電圧保持回路４７は、２つのデプレッションＩＧＢＴ５０，５１と、抵抗５２〜５５と、２つのＭＯＳＦＥＴ（Metal-Oxide Semiconductor Field-Effect Transistor）５６，５７と、コンデンサ５８とから構成されている。
【００４７】
デプレッションＩＧＢＴ５０，５１は、それぞれコレクタがＩＧＢＴ２のコレクタに接続され、ゲートおよびエミッタはともに接続され、抵抗５２，５３および抵抗５４，５５を介して接地されている。ＭＯＳＦＥＴ５６のゲートは、抵抗５４，５５の共通接続点に接続され、ドレインは抵抗５２，５３の共通接続点に接続され、ソースはコンデンサおよび演算増幅器４８の非反転入力に接続されている。また、ＭＯＳＦＥＴ５７のゲートは、入力端子７に接続され、ドレインはデプレッションＩＧＢＴ５１のゲートおよびエミッタと抵抗５４との共通接続点に接続され、ソースは接地されている。演算増幅器４８では、その電源端子が入力端子７に接続され、非反転入力は基準電圧源４９に接続され、出力はタイマ回路１４ａに接続されている。
【００４８】
この回路によれば、入力信号１９によりＩＧＢＴ２がターンオフ動作しているときには、ＩＧＢＴ２のコレクタ・エミッタ間電圧Ｖ_CEに比例した電流がデプレッションＩＧＢＴ５０に流れ、抵抗５２，５３の共通接続点に分圧された電圧が生じる。このとき、デプレッションＩＧＢＴ５１、抵抗５４，５５に流れる電流によって抵抗５４，５５の共通接続点に分圧された電圧によりＭＯＳＦＥＴ５６がターンオン動作状態になるため、抵抗５２，５３の共通接続点に分圧された電圧は、ＭＯＳＦＥＴ５６を介してコンデンサ５８に充電され、保持される。
【００４９】
次に、入力端子７に入力信号１９が印加されると、ＭＯＳＦＥＴ５７がターンオン動作状態となり、ＭＯＳＦＥＴ５６のゲート電圧をアース電位の方向に引き込むため、ＭＯＳＦＥＴ５６はターンオフ動作状態になり、コンデンサ５８は、入力信号１９の印加直前の電池１７の電圧に対応した電圧を保持することになる。このとき、入力信号１９の印加と同時に、入力信号１９を電源とする演算増幅器４８が動作し、コンデンサ５８の電圧は、演算増幅器４８によって基準電圧源４９の電圧と比較され、その比較結果はタイマ回路１４ａに出力される。演算増幅器４８からの信号が入力されたタイマ回路１４ａは、演算増幅器４８の電圧比較の結果、電池１７の電圧が高い場合には、電池１７の電圧が低い場合よりも短い時間で主電流漸減開始信号を電流制限／主電流漸減回路４０ａに出力し、スイッチングデバイスが熱破壊するのを防止する。
【００５０】
なお、上記の例では、１組の演算増幅器４８および基準電圧源４９を設けて、電池１７の電圧がある規定電圧より高いか低いかを判断し、高い場合に低い場合よりも短い時間で主電流漸減開始信号を出力するようにしたが、そのような演算増幅器および基準電圧源を複数組設けて、電池１７の電圧の高さに応じて主電流漸減開始信号が出力するまでの時間を順次短くするようにタイマ回路１４ａを制御してもよい。
【００５１】
また、電流制限／主電流漸減回路４０ａとして、図１、図４または図５に例示した電流制限回路および主電流漸減回路で構成することができる。
図９は点火用半導体装置を１チップで構成した例を示す図である。この図９において、図４に示した要素と同じ要素については同じ符号を付してその詳細な説明は省略する。この点火用半導体装置１は、点火コイル１６に流れる主電流を制御する出力段素子のＩＧＢＴ２ａと、主電流の電流検出用のＩＧＢＴ２ｂと、主電流を制限する電流制限回路と、点火コイルから放出される電圧を制限（クランプ）するツェナーダイオード３と、主電流漸減回路とを１つのシリコン基板上に形成したモノリシック集積回路とし、外部端子として、入力端子７と、出力端子５９と、グランド端子６０とを備えている。この回路において、電力容量値の大きなシャント抵抗４をシリコン基板上に作ることができないので、主電流制御用のＩＧＢＴ２ａに電流検出用のＩＧＢＴ２ｂを並列に接続し、このＩＧＢＴ２ｂに主電流の一部を分流させ、その分流電流を検出することで、主電流の値を検出するようにしている。
【００５２】
図示の例では、電流制限回路および主電流漸減回路として図４に例示したものを示したが、もちろん、図１、図３または図５に示した電流制限回路および主電流漸減回路で構成してもよい。また、同時に、図６に示した主電流遮断回路または図８に示したタイマ制御回路を含むように構成することもできる。
【００５３】
【発明の効果】
以上説明したように、本発明では、入力信号が長時間連続して印加された場合に入力信号に無関係に点火コイル電流を遮断するようにしたセルフシャットダウン回路として、出力段素子を低速でターンオフ動作させるように構成した。これにより、セルフシャットダウンのとき、出力段素子は通常動作時のターンオフ動作よりもゆっくりオフ状態になるため、点火コイルに高圧電圧が発生することが抑制され、エンジンに異常な回転力を与えることがなくなる。また、異常な回転力を与えないため、エンジンからの異常音、異常振動が発生せず、静粛な車両を提供することが可能になる。
【００５４】
また、電池電圧が高い場合であって駆動信号が連続して印加された場合に、スイッチングデバイスの主電流を強制的に高速で遮断する回路を備える構成にした。これにより、スイッチングデバイスに過大な電圧が加わることによる熱破壊を防止することが可能になる。
【００５５】
さらに、スイッチングデバイスがオフ時にこのスイッチングデバイスに印加される電池電圧を記憶保持する手段と、電池電圧に応じてタイマ回路が主電流漸減開始信号を出力するまでの時間を制御する構成にした。これにより、点火用半導体装置を、電池電圧をモニタするための端子を設けることなく、入力端子、点火コイル接続用の出力端子および接地用のグランド端子からなる既存の３端子パッケージのままで構成することができ、かつ、電池電圧に応じて主電流漸減開始信号を出力するまでの時間を制御するようにしたことで、スイッチングデバイスの熱破壊を防止することができるようになる。
【図面の簡単な説明】
【図１】本発明による点火用半導体装置の第１の実施の形態における構成例を示す回路図である。
【図２】点火コイルの２次側電圧と１次側電流・電圧の関係を示す図であって、（Ａ）は点火コイル周りを示し、（Ｂ）は点火コイルの１次側電流・電圧の変化を示し、（Ｃ）は点火コイルの２次側電圧の変化を示している。
【図３】点火用半導体装置の第２の実施の形態における構成例を示す回路図である。
【図４】点火用半導体装置の第３の実施の形態における構成例を示す回路図である。
【図５】点火用半導体装置の第４の実施の形態における構成例を示す回路図である。
【図６】点火用半導体装置の第５の実施の形態における構成例を示す回路図である。
【図７】点火用半導体装置の第６の実施の形態における構成例を示す回路図である。
【図８】点火用半導体装置の第６の実施の形態における構成をより具体的に示した回路図である。
【図９】点火用半導体装置を１チップで構成した例を示す図である。
【符号の説明】
１点火用半導体装置
２ＩＧＢＴ
３ツェナーダイオード
４シャント抵抗
５，５ａ，５ｂ，６抵抗
７入力端子
８演算増幅器
９，１０抵抗
１１コンデンサ
１２定電流素子
１３ＦＥＴ
１４，１４ａタイマ回路
１５ＦＥＴ
１６点火コイル
１７電池
１８ギャップ
１９入力信号
２０発振回路
２１シフト回路
２２−１〜２２−ｎ抵抗
２３−１〜２３−ｎＦＥＴ
２４，２５抵抗
２６トランジスタ
２７抵抗
２８ＦＥＴ
３１，３２，３３ＦＥＴ
３４定電流素子
３５ダイオード
４０，４０ａ電流制限／主電流漸減回路
４１，４２抵抗
４３基準電圧源
４４演算増幅器
４５抵抗
４６ＦＥＴ
４７オフ時Ｖ_CE電圧保持回路
４８演算増幅器
４９基準電圧源
５０，５１デプレッションＩＧＢＴ
５２〜５５抵抗
５６，５７ＭＯＳＦＥＴ
５８コンデンサ
５９出力端子
６０グランド端子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ignition semiconductor device, and more particularly to an ignition semiconductor device applied to an ignition system of an internal combustion engine for an automobile.
[0002]
[Prior art]
As an ignition system for an internal combustion engine for automobiles, a distributorless ignition system in which an ignition coil and a semiconductor device for ignition are attached to each cylinder of the internal combustion engine has become common. The ignition semiconductor device used in such a system is composed of a switching device that turns on and off the primary current of the ignition coil.
[0003]
The ignition semiconductor device provided in each cylinder is individually on / off controlled by the engine control unit, but the on / off control may not be performed normally, for example, when the engine is stalled. . In particular, when a continuous drive signal is applied to the switching device, the continuous current flows to the primary side, causing the ignition coil to be destroyed or burnt out, or only a specific cylinder to explode. Will vibrate abnormally.
[0004]
An apparatus that copes with such abnormal operation is described in, for example, Japanese Patent Application Laid-Open No. 8-28415. According to the technology described in this publication, a continuous energization prevention circuit is provided, and when the energization state of the switching device continues for a predetermined time or more by the drive signal from the engine control unit, the drive signal input to the switching device is forcibly The driving of the switching device is stopped by interrupting it. This prevents the switching device and the ignition coil from being damaged due to continuous energization.
[0005]
In addition, such a semiconductor device for ignition is provided with a current limiting circuit, and when the switching device detects an overcurrent, the switching device is prevented from being destroyed by suppressing the drive signal of the switching device. Things are also done.
[0006]
[Problems to be solved by the invention]
However, in the conventional ignition semiconductor device, the current limiting circuit prevents an overcurrent of the output stage element to prevent the ignition semiconductor device and the ignition coil from being thermally destroyed, and the continuous energization preventing circuit has a predetermined time or more. When a continuous drive signal is applied, the output signal of the ignition semiconductor device is turned off by turning off the drive signal. In particular, the turn-off operation after a certain period of time is performed at the same speed as normal. Therefore, a high voltage similar to that during normal operation is generated in the secondary winding of the ignition coil, and the gasoline mixture remaining in the cylinder may ignite and give an abnormal rotational force to the engine. There was a problem.
[0007]
The present invention has been made in view of such a point, and after the drive signal is continuously applied, the output stage element is turned off, and an unnecessary high voltage is applied to the secondary winding of the ignition coil during the off operation. An object of the present invention is to provide a semiconductor device for ignition that is prevented from being generated.
[0008]
[Means for Solving the Problems]
In the present invention, in order to solve the above problem, a switching device connected in series with the ignition coil to control on / off of the current flowing through the ignition coil, and the switching device controlled to limit the current flowing through the ignition coil. In an ignition semiconductor device equipped with a current limiting circuit for clamping and a voltage limiting circuit for clamping a voltage discharged from the ignition coil, the operation is started in response to an input signal applied to the drive terminal of the switching device. A timer circuit that outputs an output signal after a lapse of a certain time from the application of the input signal, and in response to the output signal of the timer circuit, the current flowing through the switching device regardless of the continuous application of the input signal. A main current gradual reduction circuit for reducing The current limiting circuit is connected in series with the switching device and detects a voltage value proportional to the current flowing through the switching device, and a reference voltage for generating a reference voltage value corresponding to the current limiting value. A circuit, an operational amplifier having the voltage value of the shunt resistor and the reference voltage value as inputs, and a first transistor for controlling a voltage of an input signal applied to a drive terminal of the switching device by an output of the operational amplifier The main current gradual reduction circuit includes a capacitor connected in parallel to the reference voltage circuit, a second transistor that is turned on in response to an output signal of the timer circuit, the capacitor, and the second The capacitor is connected in series to discharge the capacitor charge when the second transistor is turned on. It has a resistance and a gradually decreasing the serial reference voltage value, to turn-off operation of the switching device by response gradually decreasing the reference voltage value to an output signal of said timer circuit An ignition semiconductor device is provided.
[0009]
According to such an ignition semiconductor device, when an input signal for driving the switching device to be turned on is continuously applied, the timer circuit outputs an output signal, and in response to the output signal, the main current gradually decreases. The circuit is controlled to reduce the current flowing through the switching device. As a result, the switching device performs the off operation at a lower speed than the normal off operation, whereby the current flowing through the primary winding of the ignition coil is cut off at a low speed, and thus a high voltage is generated in the secondary winding. Is suppressed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a circuit diagram showing a configuration example of a first embodiment of an ignition semiconductor device according to the present invention. The ignition semiconductor device 1 uses an IGBT (Insulated Gate Bipolar Transistor) 2 as a switching device which is an output stage element. A Zener diode 3 for clamping a voltage discharged from the ignition coil is connected between the collector and the gate of the IGBT 2. The emitter of the IGBT 2 is grounded via a shunt resistor 4, and the gate is connected to the input terminal 7 via resistors 5 and 6. The connection point between the emitter of the IGBT 2 and the shunt resistor 4 is connected to the non-inverting input of the operational amplifier 8, and the inverting input of the operational amplifier 8 is connected to the common connection point of the resistors 9 and 10, the capacitor 11 and the constant current element 12, The output of the operational amplifier 8 is connected to the gate of an FET (Field-Effect Transistor) 13. The drain of the FET 13 is connected to the common connection point of the resistors 5 and 6, and the source is grounded. The input terminal 7 is also connected to the power supply terminal of the operational amplifier 8, the constant current element 12, and the timer circuit 14. The output of the timer circuit 14 is connected to the gate of the FET 15. The drain of the FET 15 is connected to the resistor 10 and the source is grounded. Further, the collector of the IGBT 2 is connected to the primary winding of the ignition coil 16, and the other end of the primary winding is connected to the battery 17. The secondary winding of the ignition coil 16 is grounded via a spark plug gap 18.
[0011]
Here, the shunt resistor 4, the operational amplifier 8, the FET 13, the resistor 5, the resistor 9, the constant current element 12, and the resistor 6 constitute a current limiting circuit for limiting the load current of the IGBT 2. The constant current element 12 is an element for generating a reference voltage for the operational amplifier 8, and the reference voltage is a value determined by the product of the current flowing through the constant current element 12 and the resistance value of the resistor 9. This corresponds to the terminal voltage when the limiting current value flows through the shunt resistor 4.
[0012]
Further, the capacitor 11, the resistor 10, the FET 15, and the timer circuit 14 connected in parallel to the resistor 9 constitute a self-shutdown circuit that turns off the IGBT 2 when the input signal 19 is continuously applied to the input terminal 7. However, particularly in the present invention, the self-shutdown circuit is a main current gradually decreasing circuit that performs the turn-off operation of the IGBT 2 at a low speed. The timer circuit 14 is a circuit that outputs a drive signal to the gate of the FET 15 after a lapse of a certain time from when the input signal 19 is applied.
[0013]
In the above configuration, when the input signal 19 is applied to the input terminal 7, the IGBT 2 is turned on, and a current flows from the battery 17 through the primary winding of the ignition coil 16 and the IGBT 2. Thereafter, when the input signal 19 is turned off within a time range shorter than the operation time of the timer circuit 14, the IGBT 2 performs a turn-off operation, and the current flowing through the primary winding of the ignition coil 16 is cut off. As a result, the energy stored in the primary winding of the ignition coil 16 is induced in the secondary winding, a high voltage is generated in the secondary winding, and a discharge is generated in the gap 18, and the air-fuel mixture in the cylinder is generated. Is ignited. The turn-off operation of the IGBT 2 in the normal operation is determined by the input capacitance of the IGBT 2, the resistors 5 and 6, and the resistance value of the input signal circuit, and generally operates in 50 microseconds or less.
[0014]
When the input signal 19 is applied to the input terminal 7, the potential of the input signal 19 becomes the power supply voltage of the operational amplifier 8, and a constant current is supplied to the resistor 9 by the constant current element 12. Is given a reference voltage. As a result, the current limiting circuit of the ignition semiconductor device 1 operates. When the IGBT 2 is turned on, a current flows through the shunt resistor 4. When this current increases abnormally and the terminal voltage of the shunt resistor 4 exceeds the reference voltage, the output potential of the operational amplifier 8 is inverted, and the FET 13 is turned on. By turning on and connecting the common connection point of the resistors 5 and 6 to the ground, the input signal 19 to the gate of the IGBT 2 is cut off, and the IGBT 2 is forcibly turned off.
[0015]
Next, the operation of the ignition semiconductor device when the input signal 19 is continuously applied to the input terminal 7 due to engine stall or the like will be described with reference to FIG.
FIG. 2 is a diagram showing the relationship between the secondary voltage of the ignition coil and the primary current / voltage, where (A) shows the periphery of the ignition coil, and (B) shows the primary current / voltage of the ignition coil. (C) shows the change of the secondary side voltage of the ignition coil. In FIG. 2A, IGBT2 is represented by a switch, and the current flowing through the primary winding of the ignition coil 16 is represented by I. _L , IGBT2 collector-emitter voltage is V _SW The voltage of the gap 18 generated in the secondary winding is V _C2 It is represented by
[0016]
First, the normal operation of the ignition semiconductor device 1 will be described. When IGBT2 is turned on, as shown in (B), the voltage V _SW Decreases from the battery voltage to the ground potential, and the current I flowing through the primary winding of the ignition coil 16 _L Gradually rises. Then, the current I _L When the current value exceeds a predetermined current value, the current limiting circuit operates, the current value is limited, and the voltage V _SW Will rise slightly. When the IGBT 2 is turned off, the current I _L Decreases to 0, and accordingly, the voltage V _SW Soars. This voltage V _SW Is clamped at a Zener voltage determined by the Zener diode 3, the energy of the primary winding is induced on the secondary winding side and then decreases. On the secondary winding side, a negative potential is generated by the induced energy, and as shown in FIG. _C2 Will rise in the negative direction. The voltage generated in the secondary winding is fed back to the primary winding side with a certain phase delay, and the voltage V that has been reduced is reduced. _SW Will rise again. And the voltage of the secondary winding, that is, the voltage V of the gap 18 _C2 When the voltage rises to a certain voltage, a discharge is generated in the gap 18, whereby the voltages of the primary winding and the secondary winding of the ignition coil 16 are lowered and the voltage V _SW Is the battery voltage and the voltage V of the gap 18 _C2 Becomes 0.
[0017]
Next, a case where an engine stall occurs and the input signal 19 is continuously applied will be described. When application of the input signal 19 elapses for a certain time or more, the timer circuit 14 outputs a drive signal to the gate of the FET 15. Then, the FET 15 is turned on, and the electric charge stored in the capacitor 11 is discharged through the resistor 10. The discharging speed is determined by the time constants of the capacitor 11 and the resistor 10.
[0018]
When the timer circuit 14 outputs a drive signal to the FET 15, the IGBT 2 is in a state where current is limited by the operational amplifier 8, the FET 13, and the like. When the capacitor 11 is discharged in this state, the reference voltage of the operational amplifier 8 gradually decreases. Since the IGBT 2 controls the current so that the terminal voltage of the shunt resistor 4 and the reference voltage of the operational amplifier 8 become the same, as shown by the broken line in FIG. Current I _L Will decrease. As a result, the voltage V _SW As shown by the broken line, the voltage gradually increases from the potential when the current is limited, and accordingly, the voltage V of the gap 18 is increased. _C2 Changes as indicated by a broken line in FIG. In this way, the current limit value of the IGBT 2 is changed so that the IGBT 2 is turned off at a low speed. _C2 Is not boosted to a voltage that leads to a discharge, and therefore no unnecessary explosion occurs.
[0019]
The ignition semiconductor device 1 including the current limiting circuit for limiting the load current of the IGBT 2 and the main current gradually decreasing circuit for performing the turn-off operation of the IGBT 2 at a low speed is constituted by a hybrid integrated circuit in which those components are combined. be able to. For example, a silicon chip such as IGBT2, operational amplifier 8, constant current element 12, timer circuit 14, FETs 13 and 15 is mounted on a ceramic substrate, and a printing resistor or a resistor chip is used as resistors 5, 6, 9, and 10, and a shunt resistor is installed. A resistor chip is mounted as 4 and a capacitor chip is mounted as the capacitor 11, which are connected by a wire and sealed with resin, so that they can be accommodated in one package.
[0020]
Further, the ignition semiconductor device 1 can be configured by only a plurality of semiconductor chips (bare chips) of the IGBT 2, the current limiting circuit, and the main current gradually decreasing circuit and accommodated in one package.
[0021]
Furthermore, by forming all the functions of the ignition semiconductor device 1 on a single silicon substrate, the ignition semiconductor device 1 can be configured with one chip.
FIG. 3 is a circuit diagram showing a configuration example of the ignition semiconductor device according to the second embodiment. 3, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. In the present embodiment, the main current gradual reduction circuit is configured by a timer circuit 14, an oscillation circuit 20, a shift circuit 21, n sets of resistors 22-1 to 22-n, and FETs 23-1 to 23-n. ing.
[0022]
The timer circuit 14 is a circuit that outputs a main current gradual decrease start signal after a lapse of a certain time from when the input signal 19 is applied, and its output is connected to the oscillation circuit 20. The output of the oscillation circuit 20 is connected to the shift circuit 21, and the n outputs of the shift circuit 21 are connected to the gates of the FETs 23-1 to 23-n, respectively. The series circuits of the resistors 22-1 to 22-n and the FETs 23-1 to 23-n are connected in parallel to the resistor 9 that generates the reference voltage of the operational amplifier 8, respectively. The parallel circuit of the resistor 9 and the resistors 22-1 to 22-n constitutes a circuit that reduces the reference voltage of the operational amplifier 8 in a stepwise manner.
[0023]
The oscillation circuit 20 determines the speed of reduction in a stepped manner, and the shift circuit 21 determines which FET of the FETs 23-1, FET23-n, or the FET existing between the FETs 23-1 and 23-n to be driven. It is a circuit to decide. When the resistors 22-1 to 22-n have the same resistance value, the resistance value at both ends of the resistor 9 is the resistance value if the drive signals are sequentially applied from the first FET 23-1 to the n-th FET 23-n. It becomes a parallel value of 9 and n resistance values, and the resistance value gradually decreases. The voltage across the resistor 9 becomes a voltage determined by Ohm's law (resistance × current = voltage), and as a result, the collector current of the IGBT 2 can be decreased slowly. This leads to suppression of generation of a high voltage in the secondary winding of the ignition coil 16.
[0024]
FIG. 4 is a circuit diagram showing a configuration example of the ignition semiconductor device according to the third embodiment. In FIG. 4, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. In the present embodiment, the current limiting circuit is configured by resistors 24 and 25 and a transistor 26, and the main current gradually decreasing circuit is configured by a timer circuit 14, a resistor 27, and an FET 28.
[0025]
That is, in the current limiting circuit, the connection point between the emitter of the IGBT 2 and the shunt resistor 4 is connected to the base of the transistor 26 via the resistor 24, and the collector of the transistor 26 is connected to the common connection point between the resistor 5 and the resistor 6. The emitter is grounded via a resistor 25. In the main current gradual reduction circuit, the output of the timer circuit 14 is connected to the gate of the FET 28, the drain is connected to the common connection point of the resistors 5 and 6, and the source is grounded.
[0026]
When the IGBT 2 is turned on by the application of the input signal 19 to the input terminal 7 and the main current increases, the terminal voltage of the shunt resistor 4 generated by the main current exceeds the forward bias voltage of the transistor 26. Is turned on, the potential of the common connection point of the resistors 5 and 6 is pulled in the direction of the ground potential, and the gate voltage of the IGBT 2 is lowered, thereby reducing the main current and limiting the main current to a predetermined value. To do.
[0027]
Next, when the input signal 19 is continuously applied to the input terminal 7, the timer circuit 14 outputs a drive signal after a predetermined time from when the input signal 19 is applied. As a result, the FET 28 is turned on, and the input signal 19 is shunted to the resistor 27 so as to lower the gate voltage of the IGBT 2. Further, the electric charge stored in the gate of the IGBT 2 is released through the resistor 5 and the resistor 27, and the IGBT 2 starts an off operation. The turn-off speed of the IGBT 2 is determined by the resistor 5 and the resistor 27. By increasing the resistance value of the resistor 27, the turn-off speed of the IGBT 2 can be reduced. That is, the current flowing through the primary winding of the IGBT 2 and the ignition coil 16 can be reduced slowly, and the generation of a high voltage in the secondary winding of the ignition coil 16 can be suppressed.
[0028]
FIG. 5 is a circuit diagram showing a configuration example of the ignition semiconductor device according to the fourth embodiment. In FIG. 5, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. In the present embodiment, the main current gradual reduction circuit includes the constant current element 12, the resistor 9, the diode 35, the capacitor 11, the timer circuit 14, and the FETs 31, 32, and 33.
[0029]
That is, in the main current gradual reduction circuit, the capacitor 11 is connected so that a part of the current flowing from the constant current element 12 to the resistor 9 is charged through the diode 35, and the drain of the FET 32 is discharged so that constant current is discharged. It is connected to the. The source of the FET 32 is grounded, the gate is connected to the gate and drain of the FET 33, the drain of the FET 33 is connected to the constant current element 34, and the source is grounded. These FETs 32 and 33 constitute a current mirror circuit, and the capacitor 11 is discharged at a constant current with a current determined by the constant current element 34. The output of the timer circuit 14 is connected to the gate of the FET 31, the drain is connected to the common connection point of the resistor 5 and the diode 35, and the source is grounded.
[0030]
The IGBT 2 is turned on by the application of the input signal 19 to the input terminal 7, and the reference voltage in which the terminal voltage of the shunt resistor 4 generated by the main current is determined by the constant current element 12 and the resistor 9 is increased while the main current is increasing. If exceeded, the FET 13 is turned on, the potential at the common connection point of the resistor 5 and the resistor 6 is pulled in the direction of the ground potential, and the gate voltage of the IGBT 2 is lowered, thereby reducing the main current and the main current can be determined in advance. Limit to
[0031]
Next, when the input signal 19 is continuously applied to the input terminal 7, the timer circuit 14 outputs a drive signal after a predetermined time from the application time point of the input signal 19, turns on the FET 31, and turns on the anode of the diode 35. Set to ground potential. At this time, the diode 35 prevents the capacitor 11 from being charged, and prevents the discharge current of the capacitor 11 from flowing into the resistor 9 and the FET 31. Thereby, the FET 32 discharges the electric charge stored in the capacitor 11 with a constant current.
[0032]
When the timer circuit 14 outputs a drive signal to the FET 31, the IGBT 2 is in a state where current is limited by the operational amplifier 8, the FET 13, and the like. When the capacitor 11 is discharged in this state, a constant current determined by the ratio between the FET 33 and the FET 32 in which a constant current determined by the constant current element 34 flows in the FET 32. Therefore, the capacitor 11 is gradually discharged and the calculation is performed. The reference voltage of the amplifier 8 gradually decreases. As a result, the current flowing through the primary winding of the IGBT 2 and the ignition coil 16 is slowly reduced, and generation of a high voltage in the secondary winding of the ignition coil 16 is suppressed.
[0033]
By the way, although the battery voltage of a general automobile is 12V specification, it can be started with two batteries connected in series in a cold region, etc., or even in summer, the battery deteriorates and cannot be restarted. The engine may be started using the power source. Naturally, there are cases where a 12V vehicle uses the power source of a battery voltage 24V vehicle. In such a case, when the case where the input signal 19 is continuously applied to the input terminal 7 occurs, the voltage applied to the IGBT 2 that is the switching device during the current limiting operation becomes large, and the IGBT 2 is thermally destroyed. There can be.
[0034]
For example, when the battery voltage is 12V, the current limit value is 20A, and the ignition coil resistance is 0.5Ω, the collector loss of the IGBT2 is 20A × (12V−20A × 0.5Ω) = 40W. On the other hand, when a 24V power source is used in a circuit having a battery voltage of 12V, a current limit value of 20A, and an ignition coil resistance of 0.5Ω, the power consumption is 20A × (24V−20A × 0.5Ω) = 280W.
[0035]
Therefore, it is necessary to prevent the IGBT 2 of the switching device from being thermally destroyed even when the power supply voltage is higher than normal. Next, an ignition semiconductor device to which such measures are taken will be described.
[0036]
FIG. 6 is a circuit diagram showing a configuration example of the semiconductor device for ignition in the fifth embodiment. 6, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. In the present embodiment, in addition to the current limiting / main current gradually decreasing circuit 40 including the current limiting circuit and the main current gradually decreasing circuit, when the voltage of the battery 17 is equal to or higher than the specified voltage and there is a continuous input signal 19, the IGBT 2 Is provided with a main current cut-off circuit that cuts off the main current at a high speed.
[0037]
That is, the main current cut-off circuit is configured such that voltage dividing resistors 41 and 42 for detecting the collector voltage of the IGBT 2, a reference voltage source 43 for setting a specified voltage, and a non-inverting input are connected to a common connection point of the resistors 41 and 42. An operational amplifier 44 whose inverting input is connected to the reference voltage source 43, a resistor 45 connected to the output of the operational amplifier 44, and a connection of two resistors 5a and 5b whose drain is connected in series to the gate of the IGBT 2 The FET 46 is connected to the point, the source is grounded, and the gate is connected to the output of the operational amplifier 44 through the resistor 45. The power supply terminal of the operational amplifier 44 is connected to the input terminal 7. As a result, the collector voltage of the input signal 19 and the IGBT 2 is monitored, and when the input signal 19 is continuously applied when the collector voltage is equal to or higher than the specified voltage, the gate voltage of the IGBT 2 cannot be maintained in the ON state. The circuit is configured to forcibly reduce the current and cut off the main current.
[0038]
In this configuration, when the input signal 19 is continuously applied, the current limiting / main current gradual reduction circuit 40 causes the IGBT 2 to perform the operation of gradually reducing the main current after flowing a constant main current. In this case, the collector voltage of the IGBT 2 during the current limiting operation is a voltage obtained by subtracting the product of the ignition coil resistance and the current limiting value from the voltage of the battery 17, that is, V _CE = V _B −Rc × Icl is added. Where V _CE Is the collector-emitter voltage of IGBT2, V _B Is the battery voltage, Rc is the ignition coil resistance, and Icl is the current limit value.
[0039]
In this case, even when the battery voltage is high, there is almost no increase in the current limit value, so the collector voltage of the IGBT 2 increases by the increase in the battery voltage.
According to the above configuration, first, an output is generated in the operational amplifier 44 with a collector voltage value determined by the resistors 41 and 42 and the reference voltage source 43, and the FET 46 is driven. Since the FET 46 is connected in parallel between the gate and the emitter of the IGBT 2, the gate voltage of the IGBT 2 is forcibly dropped to the ground regardless of the operation of the current limiting / main current gradual reduction circuit 40, and the IGBT 2 is turned off at a high distance. Work to transition.
[0040]
The collector voltage applied to the non-inverting input of the operational amplifier 44 may be a Zener diode instead of the resistor 41. Further, a series configuration of a Zener diode and a resistor 41 may be used. Further, a constant current element may be connected in series with the resistor 41, and a collector voltage higher than a certain voltage may be shared by the constant current element.
[0041]
Further, the current limiting / main current gradually decreasing circuit 40 can be configured by the current limiting circuit and the main current gradually decreasing circuit illustrated in FIG. 1, FIG. 4, or FIG.
Next, as described above, the battery voltage of a general automobile is 12V specification, but the battery voltage may drop when the engine is started in a cold region or when the battery is deteriorated. At this time, the input signal 19 for turning on / off the switching device may be input while being controlled to have a longer on-time compared to the normal battery voltage. Therefore, the above-described main current gradual reduction circuit that operates as a protection circuit when the input signal 19 for an abnormally long time is input matches the input signal controlled to a longer time than the normal battery voltage and exceeds that time. It may be configured to operate when continuously input. However, with such a configuration, conversely, when the battery voltage increases, the switching device may be thermally destroyed. In order to prevent this, when the battery voltage exceeds a certain voltage, it is necessary to shorten the time-out period until the timer circuit outputs an output signal for starting the gradual decrease operation of the main current gradual decrease circuit. For this purpose, it is necessary for the switching device to monitor the battery voltage.
[0042]
In general, in a circuit configuration in which one of the main current circuits of the switching device is connected to the battery via the primary winding of the ignition coil 16 that is a load and the other is grounded, the switching device itself uses the battery voltage. Cannot be monitored directly. For this reason, when the battery voltage is to be monitored, another terminal for receiving a voltage signal directly from the battery is required. Hereinafter, an ignition semiconductor device having a function of monitoring the battery voltage and preventing thermal destruction of the switching device without requiring such an additional terminal will be described.
[0043]
FIG. 7 is a circuit diagram showing a configuration example in the sixth embodiment of the semiconductor device for ignition. In FIG. 7, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. In the present embodiment, as a circuit for monitoring the voltage of the battery 17, the voltage V applied between the collector and the emitter when the IGBT 2 is turned off. _CE OFF when detecting and holding V _CE The timer control circuit is configured by including a voltage holding circuit 47, an operational amplifier 48 for comparing whether or not the voltage of the battery 17 is high, and a reference voltage source 49 for voltage comparison. In addition, in this figure, the monitor circuit which comprises the main current gradual reduction circuit is made independent for explanation, Timer A circuit 14a and a current limiting / main current gradually decreasing circuit 40a are shown.
[0044]
When the timer control circuit is off, V _CE The voltage holding circuit 47 is connected to the collector of the IGBT 2 and inputs a voltage (= the voltage of the battery 17) applied to the collector when the IGBT 2 is turned off, and stores the voltage of the battery 17 following the change. In this way, when the input signal 19 for turning on the IGBT 2 is applied to the input terminal 7, the voltage value stored immediately before the input signal 19 is applied is held and output. When the IGBT 2 is turned off, its collector-emitter voltage V _CE By monitoring this, it is possible to accurately detect the voltage value of the battery 17. The operational amplifier 48 operates when the input signal 19 for turning on the IGBT 2 is applied to the input terminal 7, and the operational amplifier 48 is applied to the non-inverting input at the off time V. _CE The voltage of the battery 17 held in the voltage holding circuit 47 is compared with the voltage of the reference voltage source 49 applied to the inverting input, and the comparison result is supplied to the timer circuit 14a. The timer circuit 14a is a circuit that outputs a main current gradual decrease start signal to the current limit / main current gradual decrease circuit 40a after a predetermined time has elapsed since the input signal 19 was applied, but the voltage of the battery 17 from the operational amplifier 48 is high. When the voltage comparison result indicating is received, for example, the time constant is switched to be small, and the time from the application of the input signal 19 to the output of the main current gradual decrease start signal is shortened.
[0045]
According to such a circuit, before the input signal 19 is applied to the input terminal 7, the off-state voltage V _CE The voltage holding circuit 47 allows V before the input signal 19 is applied. _CE The voltage, that is, the voltage of the battery 17 is maintained, and the operational amplifier 48 is activated at the same time as the input signal 19 is applied. _CE V held by the voltage holding circuit 47 _CE The comparison result between the voltage and the voltage of the reference voltage source 49 is output, and the voltage comparison result signal is input to the timer circuit 14a. The timer circuit 14a to which the voltage comparison result signal is input outputs a main current gradually decreasing start signal at a time corresponding to the voltage comparison result signal. That is, when the voltage of the battery 17 is high as a result of the voltage comparison, the timer circuit 14a outputs the main current gradually decreasing start signal in a short time.
[0046]
FIG. 8 is a circuit diagram more specifically showing the configuration of the ignition semiconductor device according to the sixth embodiment.
In this figure, when the timer control circuit is off, V _CE The voltage holding circuit 47 includes two depletion IGBTs 50 and 51, resistors 52 to 55, two MOSFETs (Metal-Oxide Semiconductor Field-Effect Transistors) 56 and 57, and a capacitor 58.
[0047]
Depletion IGBTs 50 and 51 have collectors connected to the collector of IGBT 2, gates and emitters connected together, and grounded via resistors 52 and 53 and resistors 54 and 55. The gate of the MOSFET 56 is connected to the common connection point of the resistors 54 and 55, the drain is connected to the common connection point of the resistors 52 and 53, and the source is connected to the capacitor and the non-inverting input of the operational amplifier 48. The gate of the MOSFET 57 is connected to the input terminal 7, the drain is connected to the gate and emitter of the depletion IGBT 51, and a common connection point between the resistor 54 and the source is grounded. In the operational amplifier 48, the power supply terminal is connected to the input terminal 7, the non-inverting input is connected to the reference voltage source 49, and the output is connected to the timer circuit 14a.
[0048]
According to this circuit, when the IGBT 2 is turned off by the input signal 19, the collector-emitter voltage V of the IGBT 2 is _CE Current flows to the depletion IGBT 50, and a divided voltage is generated at the common connection point of the resistors 52 and 53. At this time, the MOSFET 56 is turned on by the voltage divided to the common connection point of the resistors 54 and 55 by the current flowing through the depletion IGBT 51 and the resistors 54 and 55, so that the voltage is divided to the common connection point of the resistors 52 and 53. The voltage is charged in the capacitor 58 via the MOSFET 56 and held.
[0049]
Next, when the input signal 19 is applied to the input terminal 7, the MOSFET 57 is turned on, and the gate voltage of the MOSFET 56 is pulled in the direction of the ground potential, so that the MOSFET 56 is turned off, and the capacitor 58 receives the input signal. The voltage corresponding to the voltage of the battery 17 immediately before the application of 19 is held. At this time, the operational amplifier 48 using the input signal 19 as a power source operates simultaneously with the application of the input signal 19, and the voltage of the capacitor 58 is compared with the voltage of the reference voltage source 49 by the operational amplifier 48. It is output to the circuit 14a. When the signal from the operational amplifier 48 is input, the timer circuit 14a starts gradually decreasing the main current in a shorter time when the voltage of the battery 17 is high as a result of the voltage comparison of the operational amplifier 48 than when the voltage of the battery 17 is low. A signal is output to the current limiting / main current gradual reduction circuit 40a to prevent the switching device from being thermally destroyed.
[0050]
In the above example, a set of operational amplifiers 48 and a reference voltage source 49 are provided to determine whether the voltage of the battery 17 is higher or lower than a specified voltage. The current gradual decrease start signal is output, but a plurality of such operational amplifiers and reference voltage sources are provided, and the time until the main current gradual decrease start signal is output in accordance with the voltage level of the battery 17 is sequentially determined. The timer circuit 14a may be controlled so as to shorten it.
[0051]
Further, the current limiting / main current gradually decreasing circuit 40a can be configured by the current limiting circuit and the main current gradually decreasing circuit illustrated in FIG. 1, FIG. 4, or FIG.
FIG. 9 is a diagram showing an example in which the semiconductor device for ignition is constituted by one chip. 9, the same elements as those shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof is omitted. This semiconductor device for ignition 1 is discharged from an ignition coil IGBT 2a, an output stage element for controlling a main current flowing through the ignition coil 16, a current detection IGBT 2b for main current detection, a current limiting circuit for limiting the main current, and the ignition coil. A monolithic integrated circuit in which a Zener diode 3 for limiting (clamping) a voltage to be applied and a main current gradual reduction circuit are formed on one silicon substrate, and an input terminal 7, an output terminal 59, and a ground terminal 60 as external terminals It has. In this circuit, since the shunt resistor 4 having a large power capacity value cannot be formed on the silicon substrate, a current detection IGBT 2b is connected in parallel to the main current control IGBT 2a, and a part of the main current is supplied to the IGBT 2b. The main current value is detected by dividing the current and detecting the shunt current.
[0052]
In the illustrated example, the current limiting circuit and the main current gradually decreasing circuit illustrated in FIG. 4 are shown. Of course, the current limiting circuit and the main current gradually decreasing circuit shown in FIG. 1, FIG. 3 or FIG. Also good. At the same time, the main current cut-off circuit shown in FIG. 6 or the timer control circuit shown in FIG. 8 can be included.
[0053]
【The invention's effect】
As described above, in the present invention, when the input signal is continuously applied for a long time, the output stage element is turned off at a low speed as a self-shutdown circuit that cuts off the ignition coil current regardless of the input signal. It was configured to make it. As a result, during the self-shutdown, the output stage element is turned off more slowly than the turn-off operation during normal operation, so that generation of a high voltage in the ignition coil is suppressed and an abnormal rotational force can be given to the engine. Disappear. In addition, since an abnormal rotational force is not applied, it is possible to provide a quiet vehicle without generating an abnormal sound or abnormal vibration from the engine.
[0054]
In addition, when the battery voltage is high and the drive signal is continuously applied, the circuit is configured to forcibly cut off the main current of the switching device at high speed. Thereby, it becomes possible to prevent thermal destruction due to an excessive voltage applied to the switching device.
[0055]
Further, the battery voltage applied to the switching device when the switching device is turned off is stored, and the time until the timer circuit outputs the main current gradually decreasing start signal is controlled according to the battery voltage. Thus, the ignition semiconductor device is configured as an existing three-terminal package including the input terminal, the output terminal for connecting the ignition coil, and the ground terminal for grounding, without providing a terminal for monitoring the battery voltage. In addition, since the time until the main current gradual decrease start signal is output according to the battery voltage is controlled, it is possible to prevent thermal destruction of the switching device.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a configuration example of a semiconductor device for ignition according to a first embodiment of the present invention.
FIG. 2 is a diagram showing the relationship between the secondary voltage of the ignition coil and the primary current / voltage, where (A) shows the periphery of the ignition coil, and (B) shows the primary current / voltage of the ignition coil. (C) shows the change of the secondary side voltage of the ignition coil.
FIG. 3 is a circuit diagram showing a configuration example in a second embodiment of an ignition semiconductor device;
FIG. 4 is a circuit diagram showing a configuration example of a third embodiment of an ignition semiconductor device.
FIG. 5 is a circuit diagram showing a configuration example in a fourth embodiment of an ignition semiconductor device;
FIG. 6 is a circuit diagram showing a configuration example in a fifth embodiment of an ignition semiconductor device;
FIG. 7 is a circuit diagram showing a configuration example in a sixth embodiment of an ignition semiconductor device;
FIG. 8 is a circuit diagram more specifically showing the configuration of a sixth embodiment of an ignition semiconductor device.
FIG. 9 is a diagram showing an example in which a semiconductor device for ignition is configured by one chip.
[Explanation of symbols]
1 Semiconductor device for ignition
2 IGBT
3 Zener diode
4 Shunt resistance
5,5a, 5b, 6 resistance
7 Input terminal
8 operational amplifiers
9,10 resistance
11 Capacitor
12 Constant current element
13 FET
14, 14a Timer circuit
15 FET
16 Ignition coil
17 battery
18 gap
19 Input signal
20 Oscillator circuit
21 Shift circuit
22-1 to 22-n resistance
23-1 to 23-n FET
24,25 resistance
26 transistors
27 Resistance
28 FET
31, 32, 33 FET
34 Constant current element
35 diodes
40, 40a Current limiting / main current gradually decreasing circuit
41, 42 resistance
43 Reference voltage source
44 operational amplifier
45 resistance
46 FET
47 V when off _CE Voltage holding circuit
48 operational amplifier
49 Reference voltage source
50, 51 Depletion IGBT
52-55 resistance
56, 57 MOSFET
58 capacitors
59 Output terminal
60 Ground terminal

Claims

A switching device connected in series with the ignition coil to control on / off of the current flowing through the ignition coil, a current limiting circuit for controlling the switching device to limit the current flowing through the ignition coil, and discharging from the ignition coil In a semiconductor device for ignition equipped with a voltage limiting circuit that clamps the generated voltage,
A timer circuit that starts an operation in response to an input signal applied to a drive terminal of the switching device and outputs an output signal after a lapse of a certain time from the application of the input signal;
In response to the output signal of the timer circuit, a main current gradual reduction circuit that reduces the current flowing in the switching device regardless of continuous application of the input signal;
Equipped with a,
The current limiting circuit includes a shunt resistor connected in series with the switching device to detect a voltage value proportional to the current flowing through the switching device, and a reference voltage circuit that generates a reference voltage value corresponding to the current limiting value. An operational amplifier that receives the voltage value of the shunt resistor and the reference voltage value as input, and a first transistor that controls the voltage of the input signal applied to the drive terminal of the switching device by the output of the operational amplifier; Have
The main current gradually decreasing circuit is connected in series with a capacitor connected in parallel to the reference voltage circuit, a second transistor that is turned on in response to an output signal of the timer circuit, and the capacitor and the second transistor. A resistor for gradually decreasing the reference voltage value by discharging the capacitor when the second transistor is turned on,
The timer circuit ignition and wherein a Rukoto to turn-off operation of the switching device by response gradually decreasing the reference voltage value to the output signal of the.

A switching device connected in series with the ignition coil to control on / off of the current flowing through the ignition coil, a current limiting circuit for controlling the switching device to limit the current flowing through the ignition coil, and discharging from the ignition coil In a semiconductor device for ignition equipped with a voltage limiting circuit that clamps the generated voltage,
  A timer circuit that starts an operation in response to an input signal applied to a drive terminal of the switching device and outputs an output signal after a lapse of a certain time from the application of the input signal;
  In response to the output signal of the timer circuit, a main current gradually decreasing circuit that reduces the current flowing through the switching device regardless of the continuous application of the input signal;
  With
  The current limiting circuit includes a shunt resistor connected in series with the switching device to detect a voltage value proportional to the current flowing through the switching device, and a reference voltage circuit that generates a reference voltage value corresponding to the current limiting value. An operational amplifier that receives the voltage value of the shunt resistor and the reference voltage value as input, and a first transistor that controls the voltage of the input signal applied to the drive terminal of the switching device by the output of the operational amplifier; Have
  The main current gradually decreasing circuit includes an oscillation circuit that operates in response to an output signal of the timer circuit, a shift circuit that receives an oscillation output of the oscillation circuit, and a plurality of second circuits that are turned on by the output signals of the shift circuit. A plurality of resistors each having one end connected in series with the second transistor and the other end connected in common to the reference voltage circuit to reduce the reference voltage value stepwise,
  A semiconductor device for ignition, wherein the switching device is turned off by gradually decreasing the reference voltage value in response to an output signal of the timer circuit.

A switching device connected in series with the ignition coil to control on / off of the current flowing through the ignition coil, a current limiting circuit for controlling the switching device to limit the current flowing through the ignition coil, and discharging from the ignition coil In a semiconductor device for ignition equipped with a voltage limiting circuit that clamps the generated voltage,
  A timer circuit that starts an operation in response to an input signal applied to a drive terminal of the switching device and outputs an output signal after a lapse of a certain time from the application of the input signal;
  In response to the output signal of the timer circuit, a main current gradual reduction circuit that reduces the current flowing in the switching device regardless of continuous application of the input signal;
  With
  The main current gradual reduction circuit includes a transistor that is turned on in response to an output signal of the timer circuit, and is connected in series with the transistor to shunt the input signal when the transistor is turned on, to the drive terminal of the switching device. A resistor that reduces the applied voltage and is connected in parallel to the drive terminal of the switching device to discharge the charge stored in the input capacitance of the switching device;
  A semiconductor device for ignition, wherein the switching device is turned off by diverting the input signal and discharging the charge in response to an output signal of the timer circuit.

A switching device connected in series with the ignition coil to control on / off of the current flowing through the ignition coil, a current limiting circuit for controlling the switching device to limit the current flowing through the ignition coil, and discharging from the ignition coil In a semiconductor device for ignition equipped with a voltage limiting circuit that clamps the generated voltage,
  A timer circuit that starts an operation in response to an input signal applied to a drive terminal of the switching device and outputs an output signal after a lapse of a certain time from the application of the input signal;
  In response to the output signal of the timer circuit, a main current gradually decreasing circuit that reduces the current flowing through the switching device regardless of the continuous application of the input signal;
  With
  The current limiting circuit includes a shunt resistor connected in series with the switching device to detect a voltage value proportional to the current flowing through the switching device, and a reference voltage circuit that generates a reference voltage value corresponding to the current limiting value. And an operational amplifier that inputs the voltage value of the shunt resistor and inputs the reference voltage value via a diode, and controls the voltage of the input signal applied to the drive terminal of the switching device by the output of the operational amplifier A first transistor;
  The main current gradual reduction circuit is turned on in response to an output signal of the timer circuit and a capacitor connected in parallel to an input terminal of the reference voltage value of the operational amplifier, and disables the output of the reference voltage circuit. Two transistors, and a constant current discharge circuit connected in parallel to the capacitor to discharge the charge of the capacitor,
  A semiconductor device for ignition, wherein the switching device is turned off by gradually decreasing the reference voltage value in response to an output signal of the timer circuit.

When the voltage between the main terminals of the switching device and the voltage of the input signal applied to the drive terminal of the switching device are monitored, and the voltage between the main terminals is above a specified voltage during the current limiting operation of the current limiting circuit The ignition according to any one of claims 1 to 4, further comprising a main current cutoff circuit that controls the input signal to cut off the main current regardless of the operation of the main current gradual reduction circuit. Semiconductor device.

The main current cut-off circuit inputs a voltage proportional to the voltage between the main terminals of the switching device and also inputs a second reference voltage corresponding to the specified voltage, and an input signal applied to the drive terminal of the switching device And a third transistor that controls the voltage of the input signal by the output of the second operational amplifier to turn off the switching device at high speed. The semiconductor device for ignition according to claim 5, wherein:

An off-time main terminal voltage holding circuit that monitors the voltage of the battery connected via the ignition coil by holding the voltage between the main terminals during the turn-off operation of the switching device, and a specified voltage at which the voltage of the battery is The reference voltage source that generates a reference voltage corresponding to the above values, and the battery that is held in the off-main-terminal voltage holding circuit using the voltage of the input signal applied to the drive terminal of the switching device as a power source When the voltage value held in the off-main-terminal voltage holding circuit exceeds the voltage of the reference voltage source by comparing the voltage proportional to the voltage of the reference voltage source and the voltage of the reference voltage source, the timer circuit And a second operational amplifier that outputs to the timer circuit a signal that shortens a time from application of the input signal to output of the output signal. To ignition semiconductor device according to any one of 4.

The off-state main terminal voltage holding circuit includes first and second voltage dividing circuits that divide the voltage of the main terminal connected to the ignition coil of the switching device, and the second voltage dividing circuit. A third transistor that is turned on by an output voltage, a second capacitor that charges an output voltage of the first voltage dividing circuit by a turn-on operation of the third transistor, and a drive terminal of the switching device. 8. The ignition semiconductor device according to claim 7, further comprising: a fourth transistor that is turned on by a voltage of an input signal to turn off the third transistor.

A plurality of sets of the second operational amplifier and the reference voltage sources having different voltage values are provided, and the time until the timer circuit outputs an output signal is changed according to the voltage of the battery. The semiconductor device for ignition according to claim 7.

2. A hybrid integrated circuit configured by combining a plurality of components including the switching device, the current limiting circuit, the voltage limiting circuit, the timer circuit, and the main current gradually decreasing circuit. The semiconductor device for ignition of any one of thru | or 4.

5. The monolithic integrated circuit according to claim 1, wherein the switching device, the current limiting circuit, the voltage limiting circuit, the timer circuit, and the main current gradually decreasing circuit are configured on one silicon substrate. The semiconductor device for ignition according to claim 1.

5. A single package comprising only a plurality of semiconductor chips constituting the switching device, the current limiting circuit, the voltage limiting circuit, the timer circuit, and the main current gradually decreasing circuit. The semiconductor device for ignition according to any one of the above.

When the voltage between the main terminals of the switching device and the voltage of the input signal applied to the drive terminal of the switching device are monitored, and the voltage between the main terminals is above a specified voltage during the current limiting operation of the current limiting circuit 13. A main current cut-off circuit that controls the input signal and cuts off the main current at high speed regardless of the operation of the main current gradual reduction circuit is included. Ignition semiconductor device.