BATTERY CHARGE CONTROL CIRCUIT

• US 20090058363A1
• Filed: 08/28/2008
• Published: 03/05/2009
• Est. Priority Date: 08/30/2007
• Status: Active Grant

• Current Assignee: Stmicroelectronics France (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SA (STMicroelectronics NV), STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Milazzo, Patrizia, Platania, Giuseppe, Nebon, Jerome, Balmefrezol, Alexandre
• Granted Patent: US 8,575,889 B2
• Time in Patent Office: Days
• US Class Current: 320/134
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load

Abstract

A DC-DC voltage down-converter for an electronic device supplied by a battery and having a bus interface for the interconnection with another electronic device capable of supplying electric power is provided. The DC-DC voltage down-converter includes a terminal coupled to a voltage supply line of the bus interface and operable to receive a input current from the another electronic device. The DC-DC voltage down-converter further includes an electric energy storage element coupled between the battery and the terminal, the electric energy storage element being operable to storage/release electric energy and a drive circuit arranged to control the storage/release of the electric energy storage element, so as to cause an electric power generated by the input current supplied by the another electronic device through the voltage supply line to re-charge the battery. The DC-DC voltage down-converter still further includes a input current feedback control circuit coupled to the terminal and arranged to monitor a value of the input current and generate a corresponding input current indication; the drive circuit configured to control the storage/release of the electric energy storage element according to the input current indication.

Claims

1. A DC-DC voltage down-converter for an electronic device supplied by a battery and having a bus interface for the interconnection with another electronic device capable of supplying electric power, the DC-DC voltage down-converter including:

a terminal adapted to be coupled to a voltage supply line of the bus interface and operable to receive an input current from the another electronic device;

an electric energy storage element coupled between the battery and the terminal, the electric energy storage element being operable to store/release electric energy;

a drive circuit arranged to control the storage/release of the electric energy storage element, so as to cause electric power generated by the input current supplied by the another electronic device through the voltage supply line to re-charge the battery; and

an input current feedback control circuit coupled to the terminal and arranged to monitor a value of the input current and generate a corresponding input current indication related to the monitored value of the input current, wherein the drive circuit is configured to control the storage/release of the electric energy storage element according to the input current indication.

2. The DC-DC voltage down-converter of claim 1, wherein the electric power released by the energy storage element to re-charge the battery generates a corresponding battery current that is provided to the battery to re-charge it, and wherein the DC-DC voltage down-converter further includes a battery current feedback control circuit coupled to the battery and arranged to monitor a value of the battery current and generate a corresponding battery current indication related to the monitored value of the battery current, wherein the drive circuit is configured to control the storage/release of the electric energy storage element also according to the battery current indication.

3. The DC-DC voltage down-converter of claim 1, wherein the electric power released by the energy storage element to re-charge the battery generates a corresponding battery voltage across the battery terminals, and wherein the DC-DC voltage down-converter further includes a battery voltage feedback control circuit coupled to the battery and arranged to monitor a value of the battery voltage and generate a corresponding battery voltage indication related to the monitored value of the battery voltage, wherein the drive circuit is configured to control the storage/release of the electric energy storage element also according to the battery voltage indication.

4. The DC-DC voltage down-converter of claim 2, wherein the drive circuit is configured to control the store/release of the electric energy storage element by driving a switching circuit adapted to selectively connect/disconnect the energy storage element with the terminal depending on at least one of the input current indication, the battery current indication and the battery voltage indication.

5. The DC-DC voltage down-converter of claim 4, wherein the input current indication, battery current indication and battery voltage indication are pulse width modulated signals, whose duty cycles depend on the value of the monitored input current, battery current and battery voltage, respectively.

6. The DC-DC voltage down converter of claim 5, wherein:

the duty cycle of the input current indication is substantially proportional to the value of the monitored input current;

the duty cycle of the battery voltage indication is caused to increase if the value of the battery voltage is lower than a desired battery voltage value and is caused to decrease as the value of the battery voltage increases above the desired battery voltage value; and

the duty cycle of the battery current indication is caused to increase if the value of the battery current is lower than a desired battery current value and is caused to decrease as the value of the battery current increases above the desired battery current value.

7. The DC-DC voltage down converter of claim 6, further including a logic circuit adapted to receive the input current indication, the battery current indication and the battery voltage indication and to provide a corresponding main indication to be provided to the drive circuit, the drive circuit being configured to drive the switching circuit for selectively connecting/disconnecting the energy storage element with the terminal according to the main indication.

8. The DC-DC voltage down converter of claim 7, wherein the main indication is a pulse width modulated signal, the drive circuit being configured to drive the switching circuit for selectively connecting/disconnecting the energy storage element with the terminal according to the duty cycle of the main indication.

9. The DC-DC voltage down converter of claim 8, wherein the logic circuit is a three-input AND logic gate, whose inputs are arranged to receive the input current indication, battery current indication and battery voltage indication, the logic circuit including an output that is arranged to provide the main indication.

10. The DC-DC voltage down converter of claim 1, wherein the bus interface includes a Universal Serial Bus connector.

11. A method for controlling the transfer of electric power to an electronic device supplied by a battery, the electric power being supplied by another electronic device adapted to be interconnected to the electronic device through a bus interface, the method comprising:

receiving a input current from the another electronic device through a voltage supply line of the bus interface;

storing/releasing electric energy into/from an electric energy storage element;

controlling the storage/release of the electric energy storage element, so as to cause an electric power generated by the input current supplied by the another electronic device through the voltage supply line to re-charge the battery;

monitoring a value of the input current; and

generating a corresponding input current indication related to the monitored value of the input current, the storing/releasing electric energy into/from electric energy storage element being carried out according to the input current indication.