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Charge control circuit

  • US 7,898,217 B2
  • Filed: 05/09/2007
  • Issued: 03/01/2011
  • Est. Priority Date: 05/09/2006
  • Status: Active Grant
First Claim
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1. A charge control circuit for adjusting a charging current flowing through a battery to be charged from a power supply, the circuit comprising:

  • a sense resistor provided on a charging path leading to the battery from the power supply;

    a charging current adjustment circuit which adjusts the charging current based on an error voltage between a voltage drop across said sense resistor and a predetermined reference voltage, wherein said sense resistor and said charging current adjusting circuit are integrated;

    a current input terminal which receives an input of the charging current;

    a battery terminal which outputs the charging current to the battery;

    a terminal for monitoring a voltage connected to an internal node at which the reference voltage appears, the reference voltage being measured by an external voltmeter through the voltage monitoring terminal in an inspection process, whereinsaid sense resistor, said charging current adjustment circuit, said current input terminal, said battery terminal, and said voltage monitoring terminal are monolithically integrated on a single semiconductor substrate, andwherein said charging current adjustment circuit comprises;

    a voltage conversion circuit which converts a voltage drop across said sense resistor into a voltage potential to ground voltage;

    a variable voltage source which generates the predetermined reference voltage;

    an error amplifier which generates an error voltage between the reference voltage and the voltage drop; and

    a current adjusting unit which adjusts an on-state of a charging transistor provided on the charging path, according to the error voltage outputted from the error amplifier,wherein said variable voltage source comprises an adjusting means which adjusts the reference voltage by a trimming process.

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