JPH0711031U - Overcurrent detection device for semiconductor high-side switch - Google Patents
Overcurrent detection device for semiconductor high-side switchInfo
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- JPH0711031U JPH0711031U JP4467893U JP4467893U JPH0711031U JP H0711031 U JPH0711031 U JP H0711031U JP 4467893 U JP4467893 U JP 4467893U JP 4467893 U JP4467893 U JP 4467893U JP H0711031 U JPH0711031 U JP H0711031U
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Abstract
(57)【要約】
【目的】 ＭＯＳＦＥＴのオン電圧から過電流状態を検
出する過電流検出回路において、非常に簡単な回路構成
で、ＩＣ化の容易な過電流検出回路を提供する。
【構成】 一方の端子を電源に接続し、他方の端子を負
荷を介して電源の他方の端子に接続しハイサイドスイッ
チとしたｎ型パワーＭＯＳＦＥＴと、ＭＯＳＦＥＴに並
列で、入力信号にもとずきＭＯＳＦＥＴをオン／オフ
し、オン時には、電源電圧より高い電圧を発生し出力す
る昇圧回路を内蔵したＭＯＳＦＥＴ駆動回路と、ＭＯＳ
ＦＥＴの一方の端子に接続し、基準電圧を発生する比較
基準電圧発生回路と、比較基準電圧発生回路の出力端子
とＭＯＳＦＥＴの他方の端子に接続し、ＭＯＳＦＥＴの
オン電圧と比較基準電圧発生回路の基準電圧とを比較す
ると共に駆動電源を、ＭＯＳＦＥＴ駆動回路の出力端子
に接続してなる比較器とよりなる。ハイサイドスイッチ
のオン時のみ比較器を駆動し過電流状態を検出できる。
(57) [Abstract] [PROBLEMS] To provide an overcurrent detection circuit which detects an overcurrent state from the on-voltage of a MOSFET and has an extremely simple circuit configuration and which can be easily integrated into an IC. [Structure] An n-type power MOSFET having one terminal connected to a power supply and the other terminal connected to the other terminal of the power supply via a load to form a high-side switch, and in parallel with the MOSFET, depending on an input signal. MOSFET is turned on / off, and when it is turned on, a MOSFET drive circuit with a built-in booster circuit that generates and outputs a voltage higher than the power supply voltage, and a MOS
Connected to one terminal of the FET to generate a reference voltage, a comparison reference voltage generation circuit, an output terminal of the comparison reference voltage generation circuit and the other terminal of the MOSFET, and the ON voltage of the MOSFET and the comparison reference voltage generation circuit. It is composed of a comparator for comparing with a reference voltage and connecting a driving power supply to an output terminal of a MOSFET driving circuit. The overcurrent condition can be detected by driving the comparator only when the high side switch is on.
Description
【０００１】[0001]
本考案は、ハイサイドスイッチとして用いるｎ型パワーＭＯＳＦＥＴの過電流 検出装置に関する。 The present invention relates to an overcurrent detection device for an n-type power MOSFET used as a high side switch.
【０００２】[0002]
トランジスタのオン／オフを利用した半導体スイッチは、配線のショートや負 荷の異常により過電流が流れることにより故障することがある。そこでこれを保 護する過電流検出装置を配置する事が必要になってきた。 図２には過電流検出装置を配置した従来のハイサイドスイッチとして用いるｎ 型パワーＭＯＳＦＥＴの一例を示す。ここでハイサイドスイッチとは、電源の低 電位側に接続した負荷に対して、電源の高電位側と負荷の間に挿入して電源をオ ン／オフするようにしたスイッチをいう。 A semiconductor switch that uses the on / off state of a transistor may fail due to an overcurrent flowing due to a short circuit in the wiring or an abnormal load. Therefore, it has become necessary to arrange an overcurrent detection device to protect this. FIG. 2 shows an example of an n-type power MOSFET used as a conventional high-side switch in which an overcurrent detection device is arranged. Here, the high-side switch is a switch that is inserted between the high potential side of the power source and the load to turn on / off the power source with respect to the load connected to the low potential side of the power source.
【０００３】 ハイサイドスイッチとして動作するｎ型パワーＭＯＳＦＥＴ（以下ＭＯＳＦＥ Ｔという）１のドレイン１ａは電源端子３に接続し、ソース１ｃは負荷２を介し て電源端子４に接続する。そして該ＭＯＳＦＥＴ１のゲート１ｂはＭＯＳＦＥＴ 駆動回路６の出力端子６ａに接続する。該ＭＯＳＦＥＴ駆動回路６は入力信号端 子５から入力されたオン信号に応じて、ＭＯＳＦＥＴ１のゲート１ｂに高電圧を 印加し、オン状態によりＭＯＳＦＥＴ１には電流が流れ、ＭＯＳＦＥＴ１のドレ インーソース間にはＭＯＳＦＥＴ１の内部抵抗に起因するオン電圧Ｖｏｎが発生 する。 このオン電圧Ｖｏｎは、ＭＯＳＦＥＴ１のゲートーソース間電圧が一定の場合 、一般にＭＯＳＦＥＴ１に流れる電流にほぼ比例する特性を示し、ＭＯＳＦＥＴ １に流れる電流が大きい程、大きい値となる。A drain 1 a of an n-type power MOSFET (hereinafter referred to as MOSFT) 1 that operates as a high side switch is connected to a power supply terminal 3, and a source 1 c is connected to a power supply terminal 4 via a load 2. The gate 1b of the MOSFET 1 is connected to the output terminal 6a of the MOSFET drive circuit 6. The MOSFET drive circuit 6 applies a high voltage to the gate 1b of the MOSFET 1 in response to the ON signal input from the input signal terminal 5, and a current flows through the MOSFET 1 due to the ON state, and the MOSFET 1 is connected between the drain and source of the MOSFET 1. An on-voltage Von is generated due to the internal resistance of the. When the gate-source voltage of the MOSFET 1 is constant, the on-voltage Von generally exhibits a characteristic that is substantially proportional to the current flowing through the MOSFET 1, and has a larger value as the current flowing through the MOSFET 1 increases.
【０００４】 ＭＯＳＦＥＴ１は過電流検出装置７に接続する。該過電流検出装置７は比較器 ８と比較基準電圧発生回路９と比較器用電源回路１０とレベル変換回路１１とＡ ＮＤ回路１２と５Ｖ電源回路１４とよりなる。 即ち、ＭＯＳＦＥＴ１のソース１ｃは比較器８の一方の入力端子８ａと接続し 、比較器８の他方の入力端子８ｂは比較基準電圧発生回路９の出力端子９ａと接 続している。この比較基準電圧発生回路９はツェナーダイオード９ｂと抵抗９ｃ 、９ｄ、９ｅよりなり、ＭＯＳＦＥＴ１のオン電圧から過電流状態か正常な電流 の状態かを判定するための判定基準の基準電圧Ｖｒを生成する。The MOSFET 1 is connected to the overcurrent detection device 7. The overcurrent detection device 7 comprises a comparator 8, a comparison reference voltage generation circuit 9, a comparator power supply circuit 10, a level conversion circuit 11, an ND circuit 12 and a 5V power supply circuit 14. That is, the source 1c of the MOSFET 1 is connected to one input terminal 8a of the comparator 8, and the other input terminal 8b of the comparator 8 is connected to the output terminal 9a of the comparison reference voltage generating circuit 9. The comparison reference voltage generating circuit 9 is composed of a Zener diode 9b and resistors 9c, 9d and 9e, and generates a reference voltage Vr as a reference for determining whether the overcurrent state or the normal current state is based on the ON voltage of the MOSFET 1. .
【０００５】 前記比較器８では、共にＭＯＳＦＥＴ１のドレイン１ａを共通の基準とする２ つの電圧、即ち前記比較基準電圧発生回路９からの基準電圧ＶｒとＭＯＳＦＥＴ １のオン電圧Ｖｏｎが入力し比較する。なお、比較器８の駆動は一方を電源端子 ３に接続した比較器用電源回路１０により駆動する。 前記比較器８の出力端子８ｃはレベル変換回路１１で論理回路の信号レベルに 変換された後、ＡＮＤ回路１２の入力端子１２ａに入力する。In the comparator 8, two voltages having the drain 1a of the MOSFET 1 as a common reference, that is, the reference voltage Vr from the comparison reference voltage generation circuit 9 and the ON voltage Von of the MOSFET 1 are input and compared. The comparator 8 is driven by the comparator power supply circuit 10, one of which is connected to the power supply terminal 3. The output terminal 8c of the comparator 8 is converted to the signal level of the logic circuit by the level conversion circuit 11, and then input to the input terminal 12a of the AND circuit 12.
【０００６】 前記ＡＮＤ回路１２のもう一方の入力端子１２ｂは入力信号端子５と接続し、 この入力端子５のオン／オフ信号が入力し、オン／オフ信号の内「１」即ちオン 信号が入力している状態で、かつ比較器８の出力が「１」即ち過電流の状態の時 にはＡＮＤ回路１２が「１」を出力する。即ち過電流検出信号出力端子１３に「 １」を出力する。なお、ＡＮＤ回路１２の駆動は、一方を電源端子３に接続した ５Ｖ電源回路１４により駆動する。The other input terminal 12b of the AND circuit 12 is connected to the input signal terminal 5, and the ON / OFF signal of the input terminal 5 is input, and “1” of the ON / OFF signals, that is, the ON signal is input. The AND circuit 12 outputs "1" when the output of the comparator 8 is "1", that is, in the state of overcurrent in the state of being on. That is, "1" is output to the overcurrent detection signal output terminal 13. The AND circuit 12 is driven by the 5V power supply circuit 14, one of which is connected to the power supply terminal 3.
【０００７】 上記、過電流検出装置７は、ＭＯＳＦＥＴ１に流れる電流をこのＭＯＳＦＥＴ １のオン電圧Ｖｏｎでモニタし、負荷２の破損や配線の短絡等の異常により規定 よりも大きな電流が流れる過電流状態になった時には過電流検出信号を過電流検 出信号出力端子１３に出力して、負荷２の異常を知らせることができる。またこ の過電流検出信号によりＭＯＳＦＥＴ１をオフするように制御すればＭＯＳＦＥ Ｔ１の保護をすることもできるのである。The above-described overcurrent detection device 7 monitors the current flowing through the MOSFET 1 with the on-voltage Von of the MOSFET 1, and an overcurrent state in which a current larger than the specified current flows due to an abnormality such as damage to the load 2 or a short circuit in wiring. When it becomes, the overcurrent detection signal can be output to the overcurrent detection signal output terminal 13 to notify the abnormality of the load 2. Further, the MOSFET 1 can be protected by controlling the MOSFET 1 to be turned off by the overcurrent detection signal.
【０００８】[0008]
【考案が解決しようとする課題】 ところで、上記従来の過電流検出装置は、ＭＯＳＦＥＴ１のオン電圧は通常０ ．２〜０．３Ｖに設定される。このためこの過電流検出装置７のようにＭＯＳＦ ＥＴ１のオン電圧から過電流を検出する方式では、比較器８の入力端子には電源 端子３の電源電圧に近い電圧が入力する。 このような状態で比較器８を正確に動作させるためには、電源電圧よりも高電 圧の電源で駆動する必要があり、そのために電源電圧よりも高い電圧を出力する 比較器用電源回路１０が必ず必要となるのである。By the way, in the above-mentioned conventional overcurrent detection device, the on-voltage of the MOSFET 1 is usually 0. It is set to 2 to 0.3V. Therefore, in the method of detecting the overcurrent from the ON voltage of the MOSFET 1 like the overcurrent detection device 7, a voltage close to the power supply voltage of the power supply terminal 3 is input to the input terminal of the comparator 8. In order to operate the comparator 8 accurately in such a state, it is necessary to drive the comparator 8 with a power source having a voltage higher than the power source voltage. Therefore, the comparator power source circuit 10 that outputs a voltage higher than the power source voltage is used. It is absolutely necessary.
【０００９】 さらに、上記従来の過電流検出装置７は、ＭＯＳＦＥＴ１をスイッチとして用 いる場合、オフ時にはＭＯＳＦＥＴ１のドレイン−ソ−ス間に電源電圧Ｖｃｃが 印加されることになる。そこで、従来の過電流検出装置で過電流を検出する場合 には、オフ時には過電流検出を行わずオン時のみに過電流検出を行うようにする 必要がある。 このために、従来の過電流検出装置ではＡＮＤ回路１２を用いて、ＭＯＳＦＥ Ｔ１がオンの状態で、かつその時のオン電圧Ｖｏｎが基準電圧Ｖｒより大きい場 合のみに過電流検出信号「１」を出力するようにしているのである。Further, in the above conventional overcurrent detection device 7, when the MOSFET 1 is used as a switch, the power supply voltage Vcc is applied between the drain and the source of the MOSFET 1 when the MOSFET 1 is off. Therefore, when detecting an overcurrent with a conventional overcurrent detection device, it is necessary to detect the overcurrent only when the switch is off and not when the switch is off. Therefore, in the conventional overcurrent detection device, the AND circuit 12 is used to output the overcurrent detection signal "1" only when the MOSFET T1 is in the ON state and the ON voltage Von at that time is larger than the reference voltage Vr. It outputs it.
【００１０】 したがって、従来の過電流検出装置ではどうしてもＡＮＤ回路１２を用いなけ ればならなくなり、そのためにＡＮＤ回路用の５Ｖ電源回路１４が必要となり、 さらには、比較器８の出力をＡＮＤ回路１２の信号レベルに変換するためのレベ ル変換回路１１を用いる必要もでてきたのである。Therefore, in the conventional overcurrent detection device, the AND circuit 12 must be used by all means, which requires the 5V power supply circuit 14 for the AND circuit, and further, the output of the comparator 8 is connected to the AND circuit 12. It has also been necessary to use the level conversion circuit 11 for converting to the signal level of.
【００１１】 以上、図２の従来の過電流検出装置７では比較基準電圧発生回路９、比較器８ の他に、比較器用電源回路１０、レベル変換回路１１、ＡＮＤ回路１２、５Ｖ電 源回路１４を必要とし、その結果回路構成が複雑で、規模が大きくなるという欠 点がある。また、従来の過電流検出装置７をＭＯＳＦＥＴ１と一体化してパワー ＭＯＳＩＣ化しようとすると、チップサイズが大きくなり、その結果コストが高 くなるという欠点があるのである。As described above, in the conventional overcurrent detection device 7 of FIG. 2, in addition to the comparison reference voltage generation circuit 9 and the comparator 8, the comparator power supply circuit 10, the level conversion circuit 11, the AND circuit 12, and the 5V power supply circuit 14 are provided. Are required, resulting in a complicated circuit configuration and a large scale. Further, if the conventional overcurrent detection device 7 is integrated with the MOSFET 1 to form a power MOSIC, there is a drawback that the chip size becomes large, resulting in a high cost.
【００１２】 本考案は上記従来過電流検出装置の欠点に鑑みなされたもので、その目的はＭ ＯＳＦＥＴのオン電圧から過電流状態を検出する過電流検出装置において、非常 に簡単な回路構成で、ＩＣ化の容易な過電流検出装置を提供することにある。The present invention has been made in view of the drawbacks of the above-described conventional overcurrent detection device, and an object thereof is to provide an overcurrent detection device for detecting an overcurrent state from an ON voltage of a MOSFET with a very simple circuit configuration. An object of the present invention is to provide an overcurrent detection device that can be easily integrated into an IC.
【００１３】[0013]
本考案の過電流検出装置は、一方の端子を、電源の一方の端子に接続し、他方 の端子を、負荷を介して前記電源の他方の端子に接続したｎ型パワーＭＯＳＦＥ Ｔを用いたハイサイドスイッチにおいて、前記ＭＯＳＦＥＴに並列で、入力信号 にもとずき前記ＭＯＳＦＥＴをオン／オフし、オン時には、少なくとも前記電源 電圧より高い電圧を発生し出力する昇圧回路を配置したＭＯＳＦＥＴ駆動回路と 、前記ＭＯＳＦＥＴの一方の端子に接続し、基準電圧を発生する比較基準電圧発 生回路と、前記比較基準電圧発生回路の出力端子と前記ＭＯＳＦＥＴの他方の端 子に接続し、前記ＭＯＳＦＥＴのオン電圧と基準電圧とを比較すると共に電源入 力端子を、前記ＭＯＳＦＥＴ駆動回路の出力端子に接続してなる比較器と、より なることを特徴とする。 The overcurrent detection device of the present invention uses an n-type power MOSFET with one terminal connected to one terminal of a power source and the other terminal connected to the other terminal of the power source through a load. In the side switch, a MOSFET drive circuit in parallel with the MOSFET, which turns on / off the MOSFET in response to an input signal, and at the time of turning on, a booster circuit which generates and outputs a voltage higher than at least the power supply voltage, A comparison reference voltage generating circuit connected to one terminal of the MOSFET to generate a reference voltage, an output terminal of the comparison reference voltage generating circuit and the other terminal of the MOSFET, and an ON voltage of the MOSFET. It is characterized by comprising a comparator for comparing with a reference voltage and connecting a power supply input terminal to an output terminal of the MOSFET drive circuit. To.
【００１４】[0014]
本考案の過電流検出装置において、ハイサイドスイッチとして働くＭＯＳＦＥ Ｔと負荷には、電源端子から電源電圧を供給する。そして入力信号端子にオン信 号が入力すると、ＭＯＳＦＥＴ駆動回路の出力は高電圧になりＭＯＳＦＥＴをオ ン状態にするとともに比較器も駆動にする。 In the overcurrent detection device of the present invention, the power supply voltage is supplied from the power supply terminal to the MOSFET and the load that act as the high side switch. When an ON signal is input to the input signal terminal, the output of the MOSFET drive circuit becomes a high voltage, turning on the MOSFET and driving the comparator.
【００１５】 そしてＭＯＳＦＥＴに流れる電流が正常な範囲であって、該ＭＯＳＦＥＴのド レインーソ−ス間のオン電圧が比較基準電圧発生回路の基準電圧よりも小さい場 合には、比較器の出力はローレベルの「０」となる。逆にＭＯＳＦＥＴに流れる 電流が過電流の状態となり、オン電圧が比較基準電圧発生回路の基準電圧よりも 大きい場合には、比較器の出力はハイレベル「１」を出力することになるのであ る。When the current flowing through the MOSFET is in the normal range and the on-voltage between the drain and source of the MOSFET is smaller than the reference voltage of the comparison reference voltage generating circuit, the output of the comparator is low. The level becomes "0". On the contrary, when the current flowing in the MOSFET becomes an overcurrent state and the ON voltage is higher than the reference voltage of the comparison reference voltage generating circuit, the output of the comparator outputs a high level “1”. .
【００１６】 次に入力信号端子にオフ信号が入力すると、ＭＯＳＦＥＴ駆動回路の出力はほ ぼ零の低電圧になり、ＭＯＳＦＥＴはオフ状態になることから、電流はながれず 、同時に比較器に供給される電源電圧もほぼ零になるので、比較器は動作せず停 止することから出力も必然的にローレベル「０」の状態となるのである。 このように本考案の過電流検出装置では、比較器の出力をそのまま過電流検出 信号として出力し、負荷の異常を知らせることができる。Next, when an OFF signal is input to the input signal terminal, the output of the MOSFET drive circuit becomes a low voltage of almost zero and the MOSFET is in an OFF state. Therefore, no current flows and the current is supplied to the comparator at the same time. Since the power supply voltage for the power supply becomes almost zero, the comparator does not operate and is stopped, so that the output is inevitably at the low level "0". As described above, in the overcurrent detection device of the present invention, the output of the comparator can be directly output as the overcurrent detection signal to notify the abnormality of the load.
【００１７】[0017]
以上の如く、本考案の過電流検出装置によれば、比較器をＭＯＳＦＥＴのオン 時に電源電圧よりも高い電圧を出力するＭＯＳＦＥＴ駆動回路の出力により駆動 するするようにしたことにより、従来の過電流検出装置で必要であった比較器用 電源回路を必要とはしない。またＭＯＳＦＥＴのオフ時には同期して比較器の出 力はローレベルの「０」状態になるので、従来の過電流検出装置で必要であった ＡＮＤ回路も必要としない。 その結果、従来の過電流検出装置で必要なレベル変換回路と５Ｖ電源回路も削 除でき、本考案の過電流検出装置を非常に簡単な回路構成にすることができるの である。 As described above, according to the overcurrent detection device of the present invention, the comparator is driven by the output of the MOSFET drive circuit that outputs a voltage higher than the power supply voltage when the MOSFET is turned on. It does not require the power supply circuit for the comparator that was necessary for the detector. Further, when the MOSFET is off, the output of the comparator becomes a low level “0” state in synchronization, so that the AND circuit required in the conventional overcurrent detection device is not required. As a result, the level conversion circuit and the 5V power supply circuit required in the conventional overcurrent detection device can be eliminated, and the overcurrent detection device of the present invention can have a very simple circuit configuration.
【００１８】[0018]
以下、実施例により本考案の過電流検出装置をさらに詳細に説明する。 図１は本考案の一実施例を示す回路であり、図２に示す従来例と同一の部分に は同一符号を付し説明は省略する。 Hereinafter, the overcurrent detection device of the present invention will be described in more detail with reference to embodiments. FIG. 1 is a circuit showing an embodiment of the present invention. The same parts as those in the conventional example shown in FIG.
【００１９】 本実施例の過電流検出装置において、ハイサイドスイッチとして用いるＭＯＳ ＦＥＴ１の一方のドレイン端子１ａは電源端子３に接続し、他方のソース端子１ ｃは負荷２を介して電源端子４に接続する。そして、ＭＯＳＦＥＴ１は過電流検 出装置１５に接続する。該過電流検出装置１５は基準電圧を発生する比較基準電 圧発生回路１６と電圧を比較する比較器１７とよりなる。 前記ＭＯＳＦＥＴ１に並列に接続したＭＯＳＦＥＴ駆動回路６の出力端子６ａ は前記ＭＯＳＦＥＴ１のゲート端子１ｂに接続し、入力信号端子５の入力信号に もとずきオン時には、配置した昇圧回路の働きにより、少なくとも電源電圧より 高い電圧を発生し出力する。In the overcurrent detection device of this embodiment, one drain terminal 1 a of the MOS FET 1 used as the high side switch is connected to the power supply terminal 3, and the other source terminal 1 c is connected to the power supply terminal 4 via the load 2. Connecting. The MOSFET 1 is connected to the overcurrent detection device 15. The overcurrent detecting device 15 comprises a comparison reference voltage generating circuit 16 for generating a reference voltage and a comparator 17 for comparing the voltage. The output terminal 6a of the MOSFET drive circuit 6 connected in parallel to the MOSFET 1 is connected to the gate terminal 1b of the MOSFET 1 and at least when the input signal of the input signal terminal 5 is turned on, the booster circuit arranged at least operates. Generates and outputs a voltage higher than the power supply voltage.
【００２０】 前記電源端子３に接続し、基準電圧を発生する比較基準電圧発生回路１６はツ ェナーダイオード１６ｂと抵抗１６ｃ、１６ｄ、１６ｅよりなり、該比較基準電 圧発生回路１６の出力端子１６ａは比較器１７の入力端子１７ａに接続する。 また、前記比較器１７の他方の入力端子１７ｂは前記ＭＯＳＦＥＴ１の他方の ソース端子１ｃに接続される比較器１７は、前記ＭＯＳＦＥＴ１のオン電圧と基 準電圧とを比較し、前記ＭＯＳＦＥＴ１のオン電圧が基準電圧より高い場合、過 電流検出装置１５の過電流検出信号出力端子１８に出力する。前記比較器１７の 電源入力端子１７ｃは、前記ＭＯＳＦＥＴ駆動回路６の出力端子６ａに接続する 。A comparison reference voltage generation circuit 16 that is connected to the power supply terminal 3 and generates a reference voltage includes a Zener diode 16b and resistors 16c, 16d and 16e, and an output terminal 16a of the comparison reference voltage generation circuit 16 is It is connected to the input terminal 17a of the comparator 17. The other input terminal 17b of the comparator 17 is connected to the other source terminal 1c of the MOSFET 1. The comparator 17 compares the on-voltage of the MOSFET 1 with a reference voltage, and the on-voltage of the MOSFET 1 is When the voltage is higher than the reference voltage, it is output to the overcurrent detection signal output terminal 18 of the overcurrent detection device 15. The power input terminal 17c of the comparator 17 is connected to the output terminal 6a of the MOSFET drive circuit 6.
【００２１】 本実施例の動作について説明する。 本実施例の過電流検出装置において、ハイサイドスイッチとして働くＭＯＳＦ ＥＴ１と負荷２には、電源端子３と電源端子４から電源電圧が供給されている。 そこで、入力信号端子５にオン信号が入力されると、ＭＯＳＦＥＴ駆動回路６の 出力は高電圧になりＭＯＳＦＥＴ１をオンにするとともに比較器１７を動作状態 にする。The operation of this embodiment will be described. In the overcurrent detection device of this embodiment, the power supply voltage is supplied from the power supply terminal 3 and the power supply terminal 4 to the MOSF ET1 and the load 2 that function as high-side switches. Therefore, when an ON signal is input to the input signal terminal 5, the output of the MOSFET drive circuit 6 becomes a high voltage, turning on the MOSFET 1 and turning on the comparator 17.
【００２２】 この時ＭＯＳＦＥＴ１を十分にオンの状態にするには、ＭＯＳＦＥＴ駆動回路 ６の出力をドレインの電圧即ち電源電圧よりも高くする必要があり、そのために 本実施例でもＭＯＳＦＥＴ駆動回路６の出力は電源電圧（例えば、１２Ｖ）より も高い電圧（例えば、２０Ｖ）まで昇圧する。At this time, in order to sufficiently turn on the MOSFET 1, the output of the MOSFET drive circuit 6 needs to be higher than the drain voltage, that is, the power supply voltage. Therefore, in this embodiment as well, the output of the MOSFET drive circuit 6 is increased. Boosts to a voltage (eg, 20V) higher than the power supply voltage (eg, 12V).
【００２３】 前記比較器１７の高電位側の電源入力端子１７ｃはＭＯＳＦＥＴ駆動回路６の 出力端子６ａに接続されているので、ＭＯＳＦＥＴ１がオン状態では、比較器１ ７は電源電圧よりも高い電圧で駆動されることになり、正常に比較動作を行う。Since the power supply input terminal 17c on the high potential side of the comparator 17 is connected to the output terminal 6a of the MOSFET drive circuit 6, when the MOSFET 1 is in the ON state, the comparator 17 has a voltage higher than the power supply voltage. It is driven, and the comparison operation is performed normally.
【００２４】 そしてＭＯＳＦＥＴ１に流れる電流が正常な範囲であって、ドレインーソ−ス 間のオン電圧Ｖｏｎが比較基準電圧発生回路１６の基準電圧Ｖｒよりも小さい場 合には、比較器１７の出力はローレベルの「０」となる。逆にＭＯＳＦＥＴ１に 流れる電流が過電流の状態であって、オン電圧Ｖｏｎが比較基準電圧発生回路１ ６の基準電圧Ｖｒよりも大きい場合には、比較器１７の出力端子１７ｅにはハイ レベル「１」を出力することになるのである。When the current flowing through the MOSFET 1 is in the normal range and the on-voltage Von between the drain and source is smaller than the reference voltage Vr of the comparison reference voltage generation circuit 16, the output of the comparator 17 is low. The level becomes "0". On the contrary, when the current flowing in the MOSFET 1 is in the overcurrent state and the on-voltage Von is higher than the reference voltage Vr of the comparison reference voltage generation circuit 16, the output terminal 17e of the comparator 17 has a high level "1". Will be output.
【００２５】 次に入力信号端子５にオフ信号が入力されると、ＭＯＳＦＥＴ駆動回路６の出 力はほぼ零の低電圧になり、ＭＯＳＦＥＴ１はオフ状態となり、ＭＯＳＦＥＴ１ には電流は流れず、同時に比較器１７に供給される電源電圧もほぼ零になること から、比較器１７は駆動せず停止し、出力も必然的にローレベルの「０」の状態 となる。Next, when the OFF signal is input to the input signal terminal 5, the output of the MOSFET drive circuit 6 becomes a low voltage of almost zero, the MOSFET 1 is in the OFF state, and no current flows in the MOSFET 1 so that the comparison is performed simultaneously. Since the power supply voltage supplied to the device 17 also becomes almost zero, the comparator 17 is stopped without being driven, and the output is inevitably in the low level “0” state.
【００２６】 本実施例の過電流検出装置１５によれば、ＭＯＳＦＥＴ１が過電流か正常かの 状態に応じて、比較器１７の出力がハイレベル「１」、ローレベル「０」の状態 となるので、比較器１７の出力をそのまま過電流検出信号として過電流検出信号 出力端子１８から出力し、負荷２の異常を知らせることができるのである。According to the overcurrent detection device 15 of the present embodiment, the output of the comparator 17 becomes a high level “1” and a low level “0” depending on whether the MOSFET 1 is overcurrent or normal. Therefore, the output of the comparator 17 can be output as it is from the overcurrent detection signal output terminal 18 as an overcurrent detection signal to notify the abnormality of the load 2.
【００２７】 本考案は上記実施例に限定されるものではない。上記実施例において、比較器 １７をＭＯＳＦＥＴ駆動回路６の出力で直接駆動する構成にしているが、これを 変形して、ＭＯＳＦＥＴ駆動回路の出力を直列抵抗を通して比較器１７の電源端 子１７ｃに接続し、該接続点と電源端子４の間に電源電圧より高いツェナー電圧 を有するツェナーダイオードを接続する如く構成してもよい。こうすれば、比較 器１７の電源電圧１７ｃに印加される電圧は前記ツェナーダイオードの電圧でク ランプされるので、高くなり過ぎることはないからである。The present invention is not limited to the above embodiment. Although the comparator 17 is directly driven by the output of the MOSFET drive circuit 6 in the above embodiment, this is modified so that the output of the MOSFET drive circuit is connected to the power supply terminal 17c of the comparator 17 through a series resistor. However, a Zener diode having a Zener voltage higher than the power supply voltage may be connected between the connection point and the power supply terminal 4. This is because the voltage applied to the power supply voltage 17c of the comparator 17 is clamped by the voltage of the Zener diode, so that it does not become too high.
【００２８】 さらに、上記実施例では、比較基準電圧発生回路１６をツェナーダイオードと 抵抗で構成したが、他の回路構成でもよい。特に基準電圧ＶｒにＭＯＳＦＥＴ１ のオン電圧Ｖｏｎの温度特性と同じ温度特性を持たせる如く構成すれば、正常な 電流状態か過電流の状態かを判定する基準電流の値を温度によらずほぼ一定にで き、過電流検出を安定に行うようにすることができるからである。Further, in the above embodiment, the comparison reference voltage generating circuit 16 is composed of a Zener diode and a resistor, but other circuit structures may be used. In particular, if the reference voltage Vr is constructed so as to have the same temperature characteristic as the temperature characteristic of the on-voltage Von of the MOSFET 1, the value of the reference current for determining whether it is a normal current state or an overcurrent state is substantially constant regardless of temperature. This is because the overcurrent can be detected stably.
【００２９】[0029]
【図１】実施例の過電流検出装置を含む半導体ハイサイ
ドスイッチ回路を示す構成図FIG. 1 is a configuration diagram showing a semiconductor high side switch circuit including an overcurrent detection device according to an embodiment.
【図２】従来の過電流検出装置を含む半導体ハイサイド
スイッチ回路を示す構成図FIG. 2 is a configuration diagram showing a semiconductor high side switch circuit including a conventional overcurrent detection device.
１・・・・・・ ｎ型パワーＭＯＳＦＥＴ ２・・・・・・ 負荷 ５・・・・・・ 入力信号端子 ６・・・・・・ ＭＯＳＦＥＴ駆動回路 ７、１５・・・ 過電流検出装置 ８、１７・・・ 比較器 ９、１６・・・ 比較基準電圧発生回路 １０・・・・・・ 比較器用電源回路 １１・・・・・・ レベル変換回路 １２・・・・・・ ＡＮＤ回路 １４・・・・・・ ５Ｖ電源回路 1 n-type power MOSFET 2 load 5 input signal terminal 6 MOSFET drive circuit 7 15 overcurrent detection device 8 , 17 ... Comparator 9, 16 ... Comparison reference voltage generating circuit 10 ... Comparator power supply circuit 11 ... Level conversion circuit 12 ... AND circuit 14 ...・ ・ ・ ・ ・ 5V power supply circuit
Claims (1)
し、他方の端子を、負荷を介して前記電源の他方の端子
に接続したｎ型パワーＭＯＳＦＥＴを用いたハイサイド
スイッチにおいて、 前記ＭＯＳＦＥＴに並列で、入力信号にもとずき前記Ｍ
ＯＳＦＥＴをオン／オフし、オン時には、少なくとも前
記電源電圧より高い電圧を発生し出力する昇圧回路を配
置したＭＯＳＦＥＴ駆動回路と、 前記ＭＯＳＦＥＴの一方の端子に接続し、基準電圧を発
生する比較基準電圧発生回路と、 前記比較基準電圧発生回路の出力端子と前記ＭＯＳＦＥ
Ｔの他方の端子に接続し、前記ＭＯＳＦＥＴのオン電圧
と前記比較基準電圧発生回路の基準電圧とを比較すると
共に電源入力端子を、前記ＭＯＳＦＥＴ駆動回路の出力
端子に接続してなる比較器と、 よりなることを特徴とするハイサイドスイッチの過電流
検出装置。1. A high-side switch using an n-type power MOSFET in which one terminal is connected to one terminal of a power source and the other terminal is connected to the other terminal of the power source via a load, In parallel with the MOSFET, the above M based on the input signal
A MOSFET drive circuit in which a booster circuit for generating and outputting a voltage at least higher than the power supply voltage is arranged when the OSFET is turned on / off, and a comparison reference voltage which is connected to one terminal of the MOSFET and generates a reference voltage A generation circuit, an output terminal of the comparison reference voltage generation circuit, and the MOSFE
A comparator connected to the other terminal of T for comparing the on-voltage of the MOSFET with the reference voltage of the comparison reference voltage generation circuit and connecting a power supply input terminal to the output terminal of the MOSFET drive circuit; An overcurrent detection device for a high-side switch, comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4467893U JPH0711031U (en) | 1993-07-23 | 1993-07-23 | Overcurrent detection device for semiconductor high-side switch |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4467893U JPH0711031U (en) | 1993-07-23 | 1993-07-23 | Overcurrent detection device for semiconductor high-side switch |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0711031U true JPH0711031U (en) | 1995-02-14 |
Family
ID=12698101
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4467893U Pending JPH0711031U (en) | 1993-07-23 | 1993-07-23 | Overcurrent detection device for semiconductor high-side switch |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0711031U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8879226B2 (en) | 2010-10-20 | 2014-11-04 | Rohm Co., Ltd. | High side switch circuit, interface circuit and electronic device |
-
1993
- 1993-07-23 JP JP4467893U patent/JPH0711031U/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8879226B2 (en) | 2010-10-20 | 2014-11-04 | Rohm Co., Ltd. | High side switch circuit, interface circuit and electronic device |
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