# US 7,746,036 B2 · Load current dependent reduction of charge battery current

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- Number: US 7,746,036 B2
- Document ID: US7746036B2
- Status: Granted
- Kind: B2
- Application number: 12/150,977
- Filed: 2008-05-02
- Published: 2009-10-29
- Granted: 2010-06-29
- Earliest claimed: 2008-04-29
- Assignees: Dialog Semiconductor GmbH
- Inventors: Christian Wolf; David Lloyd; Anthony Clowes
- Web page: https://patentgrep.com/patent/US7746036B2

## CPC

- H02J 7/865: {Battery or charger load switching, e.g. concurrent charging and load supply (H02J7/50 takes precedence)}
- G06F 1/26: Power supply means, e.g. regulation thereof (for memories G11C)
- G06F 1/30: Means for acting in the event of power-supply failure or interruption, e.g. power-supply fluctuations (for resetting only G06F1/24)
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## 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.

## Claims

### Claim 1

A method to charge batteries of portable devices simultaneously with supplying power to these devices for their operations is comprising the following steps:
(1) providing a DC power source, a supply regulator, one or more rechargeable batteries, a battery charger controlled by a digital control unit, a voltage comparator, and a capacitor;
(2) setting charge current to charge batteries to a predefined default current level;
(3) delaying process flow for a defined time interval and go then to step (4);
(4) checking if voltage at inputs of said portable device and of said battery charger is lower than a defined threshold voltage, and, if positive, go to step (5) else go to step (7);
(5) checking, if said charge current is zero, and if positive, go to step (3) else go to step (6);
(6) decreasing said charge current and go then to step (3);
(7) checking if said charge current is smaller than said predefined default current level, and if positive, go to step (8), else go to step (3); and
(8) increasing said charge current and go then to step (3).

### Claim 2 (depends on 1)

The method of claim 1 wherein said delay time has an order of magnitude of 100 μsec.

### Claim 3 (depends on 1)

The method of claim 1 wherein said DC power source has a maximum allowable current limit.

### Claim 4 (depends on 3)

The method of claim 3 wherein said DC power source is a universal serial bus (USB) port.

### Claim 5 (depends on 3)

The method of claim 3 wherein said DC power source is a Firewire/IEEE1394 port.

### Claim 6 (depends on 3)

The method of claim 3 wherein said DC power source is a current limited wall brick.

### Claim 7 (depends on 3)

The method of claim 3 wherein said supply regulator does allow a maximum output current, which is slightly lower than said maximum allowable current limit of said DC power source.

### Claim 8 (depends on 1)

The method of claim 1 wherein said digital control performs said check if said charge current is zero and sends the result to said digital control unit.

### Claim 9 (depends on 1)

The method of claim 1 wherein said digital control performs said check if said charge current is smaller than said predefined default current level and sends the result to said digital control unit.

### Claim 10 (depends on 1)

The method of claim 1 wherein said supply regulator, one or more rechargeable batteries, the battery charger, the digital control unit, and the voltage comparator are integrated in said portable device.

### Claim 11 (depends on 1)

The method of claim 1 wherein said supply regulator is a linear regulator.

### Claim 12 (depends on 1)

The method of claim 1 wherein said supply regulator is a switched regulator.

### Claim 13 (depends on 1)

The method of claim 1 wherein said digital control controls the battery charger in a way that the current required for the operation of the portable device has precedence over the charging current of the batteries.