Load current dependent reduction of charge battery current
AssigneeDialog Semiconductor GmbH
InventorsChristian Wolf, David Lloyd, Anthony Clowes
Life of this patent
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Abstract
Circuits and methods to charge batteries of a portable device simultaneously with supplying power to the device for its operation, using a power source with limited maximum current, as e.g. an USB port, have been achieved. The system invented relies upon digital control only. No direct sensing of the current required for the operation of the portable device is required. The control takes care that the sum of the charging current and of the current to run the portable device does not exceed the maximum allowable current of the power source. The current required to run the portable device has precedence over the charging current.
Claims12
A system to charge batteries of a portable device simultaneously with supplying power to the device for its operation is comprising:
- a rechargeable battery,
- a DC power source connected at its output to a supply regulator;
- said supply regulator regulating its output voltage and limiting its output current just below the maximum allowable output current of said DC power supply, wherein the output of the supply regulator is supplying the operation of the portable device and its voltage corresponds to the supply voltage level required the portable device, and the output is further connected to the power input of a battery charger, charging said rechargeable battery, to a first terminal of a capacitor, and to a first input of a voltage comparator;
- said capacitor having its second terminal connected to ground;
- said battery charger, charging with its output said rechargeable battery, having its operation controlled by a digital controller;
- said digital controller wherein an input is connected to an output of said voltage comparator and the output is connected to said battery charger;
- and
- said voltage comparator having a reference voltage as a second input comparing said reference voltage with the output voltage of said supply regulator.
Dependencies are inferred from the claim text.