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Charging apparatus with a compensation circuit

  • US 5,557,192 A
  • Filed: 08/12/1994
  • Issued: 09/17/1996
  • Est. Priority Date: 09/21/1993
  • Status: Expired due to Term
First Claim
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1. A charging apparatus with a compensation circuit comprising:

  • (a) a voltage detection circuit for measuring the voltage across terminals of circuitry including a rechargeable battery;

    (b) a charging control circuit for controlling charging, based on the voltage measured by the voltage detection circuit, such that the rechargeable battery voltage does not exceed a prescribed voltage; and

    (c) a compensation circuit for at least compensating the voltage measured by the voltage detection circuit for a voltage drop due to a resistive component in circuitry other than the rechargeable battery;

    wherein the voltage detection circuit is provided with a reference voltage device and an op-amp having a first and a second input terminal;

    wherein the terminal voltage of circuit including the rechargeable battery is input to the first input terminal of the op-amp and the reference voltage is input to the second input terminal of the op-amp for comparison;

    wherein the compensation circuit is provided with a compensation resistor connected in series with the rechargeable battery, and wherein the compensation resistor is connected to the reference voltage device such that the voltage drop across the compensation resistor is added to the voltage of the reference voltage device and input to the second input terminal of the op-amp.

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