Battery charger with Vbe temperature compensation circuit
AssigneeJohn Fluke Mfg. Co., Inc.
InventorBenjamin Eng, Jr.
Life of this patent
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Abstract
A battery charger supplies to a battery an output voltage having a desired temperature coefficient of voltage. The charger includes an operational amplifier having a summing junction to which a reference current and a feedback signal derived from the amplifier output are supplied. The V.sub.be multiplier circuit includes a bipolar transistor which is biased into its active region so that the charging voltage supplied by the amplifier is temperature corrected in accordance with a negative coefficient of voltage characteristic of the transistor.
Claims6
A battery charger for supplying to a battery an output voltage having a desired temperature coefficient of voltage, comprising:
- an operational amplifier having a summing junction and an output connected to supply a charging potential therefrom to the battery;
- means for supplying a reference current to said summing junction;
- and
- V.sub.be multiplier means connected between the output and the summing junction of said operational amplifier, said V.sub.be multiplier means including a bipolar transistor and means for biasing said bipolar transistor into an active region thereof whereby the charging voltage supplied by said amplifier is temperature compensated in accordance with a negative temperature coefficient of voltage operating characteristic of said bipolar transistor.
A charger circuit for supplying to a battery an output voltage having a desired temperature coefficient (TC), comprising:
- a voltage regulator having an input terminal and having an output connected to supply a charging voltage to the battery;
- a source of reference voltage connected to said voltage regulator input;
- and
- a base-to-emitter voltage (V.sub.be) multiplier circuit connected between said voltage regulator input and the output of said voltage regulator, said V.sub.be multiplier circuit including a bipolar transistor and transistor biasing means in circuit with said transistor for operating said transistor in an active region thereof whereby the charging voltage supplied by said voltage regulator is temperature compensated in accordance with a negative voltage-temperature coefficient operating characteristic of said transistor.
Dependencies are inferred from the claim text.