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Current detection circuit and DCDC converter including the same

  • US 10,256,725 B2
  • Filed: 03/17/2017
  • Issued: 04/09/2019
  • Est. Priority Date: 03/23/2016
  • Status: Active Grant
First Claim
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1. A current detection circuit for detecting a current from a drive circuit comprising a first drive transistor provided on a high side of the drive circuit and having a first terminal provided on an external output terminal side outputting externally an output voltage of a drive circuit, a second terminal provided on an external input terminal side to which an input voltage is supplied externally from the drive circuit, and a control terminal, the current detection circuit comprising:

  • a first sense transistor including a first terminal and a control terminal which are coupled respectively to the first terminal and the control terminal the first drive transistor, the first sense transistor being a same conductive type as the first drive transistor;

    a first operational amplifier configured to amplify a potential difference between a voltage of the second terminal of the first drive transistor and a voltage of a second terminal of the first sense transistor;

    a second operational amplifier configured to amplify a potential difference between a voltage of a first terminal of a second drive transistor and a voltage of a first terminal of a second sense transistor;

    a second resistance element provided between one of two input terminals of the second operational amplifier coupled to the ground voltage terminal with the first terminal of the second drive transistor and the ground voltage terminal; and

    a first current control transistor provided over a first current path through which a current from the first sense transistor flows, and having a control terminal to which an output voltage of the first operational amplifier is supplied,wherein a value of a current flowing through the first drive transistor is detected from a value of the current flowing through the first sense transistor, andthe second resistance element is a transistor, in an ON state, having a same conductivity as the second sense transistor,the first operational amplifier operates, when the input voltage of the drive circuit is supplied as a low potential side source voltage, and when a first voltage higher than the input voltage is supplied as a high potential side source voltage.

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