METHODS AND APPARATUS FOR CHARGING A BATTERY IN A PERIPHERAL DEVICE

• US 20070222301A1
• Filed: 05/29/2007
• Published: 09/27/2007
• Est. Priority Date: 10/22/2001
• Status: Abandoned Application

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Krah, Christoph, Fadell, Anthony
• Application Number:
  US11/754,932
• Publication Number:
  US 20070222301A1
• Time in Patent Office: Days
• US Class Current: 307/152
• CPC Class Codes: G06F 1/266 Arrangements to supply power to external peripherals either directly from the computer or under computer control, e.g. supply of power through the communication port, computer controlled power-strips
• CPC Class Codes: G06F 1/325 Power saving in peripheral device
• CPC Class Codes: H02J 1/001 Hot plugging or unplugging of load or power modules to or from power distribution networks
• CPC Class Codes: H02J 1/06 Two-wire systems
• CPC Class Codes: H02J 2207/30 Charge provided using DC bus or data bus of a computer
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence

Abstract

A power manager for managing power delivered to a battery operated peripheral device is disclosed. The power manager includes an input current limiter arranged to suppress a power surge associated with an insertion event by a power cable arranged to provide an external voltage. A voltage converter unit coupled to the input current limiter converts the received external voltage to a supply voltage that is transmitted by way of a main bus to a voltage sensor unit coupled thereto. During the insertion event, a comparator unit coupled to the voltage sensor, sends a first switching signal to a switchover circuit that responds by connecting the peripheral device and an uncharged battery to the main bus such that the supply voltage is provided thereto. When the battery is substantially fully charged, the switchover circuit responds by electrically disconnecting the battery so as to not overcharge the battery.

Claims

1. An apparatus comprising:

a circuit;

a battery;

a port that includes a power line and serial data line; and

a power management unit, coupled to the circuit, the battery, and the port,

wherein the power management unit contains instructions that when executed by the power management unit;

(i) powers the circuit with the battery if the power line does not provide power;

(ii) powers the circuit and charges the battery with power provided by the power line if the power line provides power to the apparatus.

2. The apparatus of claim 1, wherein the power management unit further comprises a voltage converter to convert an external power source voltage to a supply voltage if the external power source voltage is received through the port and is provided to the circuit.

3. The apparatus of claim 2, wherein the voltage converter of the power management unit is a step down converter configured to step down the external power supply voltage to the supply voltage.

4. The apparatus of claim 2, wherein the power management unit further comprises a charge current generator to generate a charge current to charge the battery if the external power supply voltage is received through the port and a battery power source voltage is below the supply voltage by a threshold.

5. The apparatus of claim 4, wherein the power management circuit further comprises a comparator to compare the battery power source voltage to the supply voltage.

6. The apparatus of claim 5, wherein the comparator generates a first signal if the battery power source voltage is within the threshold from the supply, the first signal provided to a charge control circuit.

7. The apparatus of claim 6, wherein the first signal further causes the charge circuit to disconnect the external power supply voltage from the battery to prevent over-charging of the battery.

8. The apparatus of claim 5, wherein the comparator generates a second signal if the battery power source voltage is below the threshold of the supply voltage, the second signal causing a charge circuit to generate a charge current to charge the battery when the external power supply voltage is received through the port.

9. The apparatus of claim 2, wherein the supply voltage is one of the following voltages:

approximately 1.8 volts, approximately 3.3 volts, approximately 5.0 volts;

or 5.0 volts or less.

10. The apparatus of claim 1, wherein the power management unit further comprises a switch circuit configured to prevent substantial interruptions in providing power to the circuit when switching from the external power supply voltage to the battery power source voltage or vice versa.

11. The apparatus of claim 1, wherein the port is configured to receive at least one power line.

12. The apparatus of claim 1, wherein the port is configured to receive at least one data line arranged to form a transmit-and-receive connection with the external source.

13. A method for providing power to a circuit contained within a portable device from either a battery contained in the device or an external power source when plugged into a port configured to receive both power and data at the device, the method comprising:

ascertaining if the external power source is plugged into the port of the device, and either;

(i) providing power to the circuit from the battery when the external power source is not plugged into the device;

(ii) providing power from the external power source to the circuit and the battery used to at least recharge the battery when the external power source is plugged into the device and when the output of the battery is below a supply voltage by more than a threshold;

or

(iii) providing power from the external power source only to the circuit when the external power source is plugged into the device and the output of the battery is within the threshold of the supply voltage.

14. The method of claim 13, further comprising converting an external power source voltage to the supply voltage within the device, wherein the supply voltage is one of the following:

approximately 1.8 volts, approximately 3.3 volts, approximately 5.0 volts;

or 5.0 volts or less.

15. The method of claim 14, wherein providing the external power to the circuit in the device and the battery to recharge the battery further comprises generating a charge current to charge the battery when an output voltage of the battery is below the supply voltage by more than the threshold.

16. The method of claim 15, further comprising comparing the battery voltage output to the supply voltage and either:

(i) generating a first signal if the battery voltage output is within the threshold from the supply voltage, the first signal causing power from the external power supply to be provided only to the circuit when the external power is received through the port;

or

(ii) generating a second signal if the battery voltage output is below the threshold of the supply voltage, the second signal causing a charge current to be provided to the battery to charge the battery when the external power is received through the port.

17. The method of claim 15, further comprising disconnecting the external power supply voltage from the battery after the battery is charged.

18. The method of claim 15, further comprising switching between (i), (ii) and (iii) such that power provided to the circuit from either the battery or the external power source voltage is substantial without interruption.

19. The method of claim 15, further comprising transmitting and/or receiving data through the port of the device.

20. A battery powered device comprising:

a rechargeable battery;

a serial port that interfaces with a serial bus cable for transmitting data to or from the device that includes a plurality of data pins and at least a power pin;

a voltage sensor that senses a voltage on the power pin; and

a battery charging circuit that draws a charging current through the power pin of the serial port to charge the battery when the battery is substantially uncharged.

21. The battery powered device of claim 20, wherein the device comprises a personal digital assistant.

22. The battery powered device of claim 20, wherein the device comprises a personal MP3 player.

23. The battery powered device of claim 20, wherein the rechargeable battery comprises a lithium ion cell.

24. The battery powered device of claim 20, wherein the rechargeable battery operates within a voltage range of 3.7 volts to 4.2 volts.

25. The battery powered device of claim 20, wherein the serial port interfaces with a serial bus cable that transmits data to or from the device at a rate of at least 100 megabits per second.

26. The battery powered device of claim 20, wherein the serial port interfaces with a serial bus cable transmits data to or from the device in an asynchronous or isochronous mode.

27. The battery powered device of claim 20, wherein the serial port interfaces with an IEEE 1394 compliant serial bus cable.

28. The battery powered device of claim 20, wherein the battery charging circuit operates in a constant current mode.

29. The battery powered device of claim 20, wherein the battery charging circuit shuts off when its supply voltage is less than 4.2 volts.

30. The battery powered device of claim 20, wherein the battery charging circuit electrically isolates the battery if the battery is fully charged.

31. The battery powered device of claim 20, wherein the charging current is 750 mA.

32. The battery powered device of claim 20, wherein the voltage sensor and the battery charging circuit are coupled to the serial port via a main bus.

33. The battery powered device of claim 20, further comprising an inrush current limiter configured to limit an inrush current that flows into the battery powered device when a serial bus cable is inserted into the serial port.

34. The battery powered device of claim 20, further comprising a voltage converter configured to convert an external voltage received at the power pins of the serial port to an internal supply voltage within the range of 1.8 volts to 5 volts.

35. The battery powered device of claim 20, further comprising an active circuit operating at a supply voltage within the range of 1.8 volts to 5 volts.

36. The battery powered device of claim 20, further comprising a comparator coupled to the voltage sensor and configured to generate a switching signal based upon the sensed voltage.

37. The battery powered device of claim 20, further comprising a switchover circuit configured to supply power to an active circuit via the battery or a supply voltage received via the power pins of the serial port.

38. A method for charging a battery of a peripheral device, comprising:

inserting a serial bus cable into a serial port of the peripheral device, the serial port comprising a power pin and a plurality of data pins through which data can be transmitted to or from the peripheral device;

sensing that the voltage at the power pin of the serial port is above a selected threshold; and

drawing a charge current through the power pin of the serial port to charge the battery of the peripheral device.

39. The method of claim 38, wherein the peripheral device comprises a personal digital assistant.

40. The method of claim 38, wherein the peripheral device comprises a personal MP3 player.

41. The method of claim 38, wherein the battery operates within a voltage range of 3.7 volts to 4.2 volts.

42. The method of claim 38, wherein the battery is considered to be uncharged when its voltage drops below 3.45 volts.

43. The method of claim 38, wherein the serial port interfaces with a serial bus cable that transmits data to or from the device in an asynchronous or isochronous mode.

44. The method of claim 38, wherein the serial port interfaces with an IEEE 1394 serial bus cable.

45. The method of claim 38, wherein the charge current is 750 mA.

46. The method of claim 38, further comprising electrically isolating the battery if the battery is substantially fully charged.

47. The method of claim 38, further comprising suppressing a power surge caused by the insertion of the serial bus cable into the serial port.

48. The method of claim 38, further comprising converting an external voltage received at the power pins of the serial port to an internal supply voltage within the range of 1.8 volts to 5 volts.

49. A system comprising:

a battery powered device having a rechargeable battery and a battery charging circuit; and

a serial bus cable coupled to the battery powered device, the serial bus cable comprising a power transmission line and a plurality of data transmission lines,

wherein the serial bus cable can transmit data to or from the battery powered device over the data transmission lines; and

wherein the battery charging circuit of the battery powered device draws a charging current through the power transmission line of the serial bus cable if the rechargeable battery is not fully charged.

50. The system of claim 49, wherein the battery powered device comprises a personal digital assistant.

51. The system of claim 49, wherein the battery powered device comprises a personal MP3 player.

52. The system of claim 49, wherein the rechargeable battery operates within a voltage range of 3.7 volts to 4.2 volts.

53. The system of claim 49, wherein the serial bus cable transmits data to or from the battery powered device at a rate of at least 100 megabits per second.

54. The system of claim 49, wherein the serial bus cable transmits data to or from the battery powered device in an asynchronous or isochronous mode.

55. The system of claim 54, wherein the serial bus cable comprises an IEEE 1394 compliant serial bus cable.

56. The system of claim 49, wherein the battery powered device electrically isolates the rechargeable battery when the battery is fully charged.

57. The system of claim 49, wherein the charging current is 750 mA.

58. The system of claim 49, wherein the battery powered device comprises an active circuit operating at a supply voltage within the range of 1.8 volts to 5 volts.

59. The system of claim 49, wherein the data transmission lines are separately-shielded twisted transmission type data lines.

60. A method for managing power delivered to a battery-operated peripheral device by way of a cable that includes a number of lines at least one of which is a power line arranged to carry electrical power from an electrical supply to the device, the method comprising:

detecting a status for the device, wherein the status is based on whether a first condition relating to a battery in the device has occurred and whether a second condition relating to connection of the cable to the electrical supply has occurred;

drawing electrical power from the electrical supply at a first current if the device has a first status; and

drawing electrical power from the electrical supply at a second current level if the device has a second status.

61. The method of claim 60, wherein the second condition is the attachment of the cable to another device.

62. The method of claim 60, wherein the second condition is the connection of the cable to another device such that a data transfer request is received by the battery-operated peripheral device.

63. The method of claim 60, further comprising converting the electrical power from an external voltage to a supply voltage by a voltage converter unit.

64. The method of claim 60, wherein the first condition is when a battery in the device is fully charged.

65. The method of claim 64, further comprising, if the battery is fully charged, providing the battery with electrical power from the electrical supply at a third current level.

66. The method of claim 65, wherein the third current level is essentially zero amps.

67. The method of claim 65, wherein the cable includes two twisted pairs of wires carrying data.

68. The method of claim 67, wherein the two twisted pairs of wires are separately shielded.

69. The method of claim 68, wherein the cable is an I.E.E.E. 1394 compliant cable.

70. A portable consumer electronic product comprising:

a sensor unit arranged to detect a status for the device, wherein the status is based on whether a first condition relating to a battery in the device has occurred and whether a second condition relating to connection of the cable to the electrical supply has occurred;

a switchover circuit arranged to draw electrical power from the electrical supply at a first current if the device has a first status, and to draw electrical power from the electrical supply at a second current level if the device has a second status.

71. The portable consumer electronic product of claim 70, further comprising a voltage converter unit arranged to convert the electrical power from an external voltage to a supply voltage.

72. The portable consumer electronic product of claim 70, wherein the switchover circuit is further arranged to, if the battery is fully charged, provide the battery with electrical power from the electrical supply at a third current level.

73. The portable consumer electronic product of claim 70, wherein the third current level is essentially zero amps.

74. The portable consumer electronic product of claim 70, wherein the cable includes two twisted pairs of wires carrying data.

75. The portable consumer electronic product of claim 74, wherein the two twisted pairs of wires are separately shielded.

76. The portable consumer electronic product of claim 75, wherein the cable is an I.E.E.E. 1394 compliant cable.