Method and apparatus to perform battery charging using a DC-DC converter circuit

• US 7,402,981 B2
• Filed: 09/30/2003
• Issued: 07/22/2008
• Est. Priority Date: 07/02/2003
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: SigmaTel Incorporated (NXP Semiconductors NV)
• Inventors: May, Marcus W., Felder, Matthew D.
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US10/675,116
• Publication Number:
  US 20050001595A1
• Time in Patent Office: 1,757 Days
• Field of Search: 320/107, 320/112, 320/114, 320/115, 320/137, 320/138
• US Class Current: 320/137
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence

Abstract

A battery converter, which is used to convert battery voltage to an output voltage to power an integrated circuit in a battery-operated mode, is placed into a battery-charge mode to charge the battery when external power source is present to power the integrated circuit and the battery needs charging.

Claims

1. An apparatus comprising:

a converter within an integrated circuit to convert a battery voltage from a battery to an output voltage to power the integrated circuit in a battery-operated mode of operation, when the battery is made available to the integrated circuit, wherein the converter includes a switching transistor circuit to alternately switch transistors to regulate the output voltage in the battery-operated mode of operation and in a battery-charge mode of operation, but the switching transistor circuit is disabled in an external powered mode of operation, when external power is present and the battery is not to be charged; and

a control unit to switch the converter in one of three modes, the battery-operated mode to convert the battery voltage to the output voltage when the external power is not present, the battery-charge mode to employ the external power to generate a current source to charge the battery and maintain the output voltage when the external power is present, and an external powered mode of operation to employ the external power to generate a voltage source to source the output voltage when the external power is present.

2. The apparatus of claim 1 further comprising an analog to digital converter to monitor the battery voltage and to transmit a signal to the control unit to indicate when the battery is to be charged.

3. The apparatus of claim 1, wherein the integrated circuit receives the external power from a Universal Serial Bus link.

4. A direct current-direct current (DC-DC) converter, which is also employed as a battery charger, comprising:

a switching transistor circuit to convert a battery voltage from a battery to an output voltage to power an integrated circuit in a battery-operated mode when the battery is made available to the integrated circuit at a first node, the switching transistor circuit including alternately switching transistors to regulate the output voltage at a second node in the battery-operated mode, the switching transistors also to regulate the output voltage at the second node and to provide charge current to charge the battery in a battery-charge mode when external power from an external source is present;

a control unit to control operation of the converter in one of three modes, the battery-operated mode to convert the battery voltage to the output voltage when the external power is not present, the battery-charge mode to employ the external power to generate a current source to charge the battery and maintain the output voltage at the second node when the external power is present, and an external powered mode-to employ the external power to generate a voltage source to source the output voltage at the second node when the external power is present; and

an enabling circuit to operate with the control unit to disable the switching transistors in the external powered mode and enable the switching transistors in the battery-operated and battery-charge modes.

5. The DC-DC converter of claim 4, wherein the enabling circuit controls signals to gates of the switching transistors to enable and disable the switching transistors.

6. The DC-DC convener of claim 5, wherein when the external power is present, the control unit to initiate the battery-charge mode-only if the battery needs charging.

7. The DC-DC convener of claim 6, wherein the enabling circuit to control enabling or disabling of the switching transistors under control of the control unit to toggle between the battery-charge and external powered modes, when the external power is present.

8. The DC-DC converter of claim 7, further comprising a switch controlled by the control unit select between the external powered and battery-charge modes in response to a state of charge of the battery.

9. The DC-DC converter of claim 8, further comprising an analog to digital converter to monitor the battery voltage and to transmit a digital signal to the control unit to indicate if the battery needs to be charged.

10. The DC-DC converter of claim 8, wherein the integrated circuit receives the external power from a Universal Serial Bus link.

11. An integrated circuit which has an audio system integrated therein, comprising:

an input interface to receive audio data input;

a digital signal processor to receive the audio input and generate processed audio data;

an output amplifier to output the processed audio data external to the integrated circuit; and

a direct current-direct current (DC-DC) converter, which is also employed as a battery charger, the DC-DC converter comprising;

(a) a switching transistor circuit to convert a battery voltage from a battery to an output voltage to power an integrated circuit in a battery-operated mode when the battery is made available to the integrated circuit at a first node, the switching transistor circuit including alternately switching transistors to regulate the output voltage at a second node in the battery-operated mode, the switching transistors also to regulate the output voltage at the second node and to provide charge current to charge the battery in a battery-charge mode when external power from an external source is present;

(b) a control unit to control operation of the converter in one of three modes, the battery-operated mode to convert the battery voltage to the output voltage when the external power is not present, the battery-charge mode to employ the external power to generate a current source to charge the battery and maintain the output voltage at the second node when the external power is present, and an external powered mode to employ the external power to generate a voltage source to source the output voltage at the second node when the external power is present; and

(c) an enabling circuit to operate with the control unit to disable the switching transistors in the external powered mode and enable the switching transistors in the battery-operated and battery-charge modes.

12. The integrated circuit of claim 11, wherein when the external power is present, the control unit to initiate the battery-charge mode only if the battery needs charging.

13. The integrated circuit of claim 12, wherein the enabling circuit to control enabling or disabling of the switching transistors under control of the control unit to toggle between the battery-charge and external powered modes, when the external power is present.

14. The integrated circuit of claim 13, wherein the DC-DC converter further comprising an analog to digital converter to monitor the battery voltage and to transmit a digital signal to the control unit to indicate if the external battery needs to be charged.

15. The integrated circuit of claim 13, wherein the external power is received from a Universal Serial Bus link.

16. A method of employing a direct current-direct current (DC-DC) converter to charge a battery comprising:

monitoring to determine if external power from a data transfer link is present to power an integrated circuit;

providing a DC-DC conversion in a first mode of operation to convert a battery voltage to generate an output voltage to power the integrated circuit, if the external power is not present;

utilizing the external power to generate a voltage source to provide the output voltage to power the integrated circuit in a second mode of operation when external power from the data transfer link is present, the second mode of operation disabling circuitry for the DC-DC conversion; and

utilizing the external power to generate a current source to power the circuitry for the DC-DC conversion to power the integrated circuit in a third mode of operation and also utilizing the same circuitry for the DC-DC conversion to charge the battery.

17. The method of claim 16 further comprising monitoring the battery voltage to determine if the battery needs charging when the external power is present to power the integrated circuit.

18. The method of claim 17, wherein the external power is provided from a Universal Serial Bus link.

19. The method of claim 17, wherein the external power is provided from a Universal Serial Bus 2.0 link.