Power distribution in a portable device

• US 20010015635A1
• Filed: 01/03/2001
• Published: 08/23/2001
• Est. Priority Date: 02/23/2000
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Weiss, Martin M., Solanki, Prashant A., Leppo, Lee Edward
• Granted Patent: US 6,362,597 B2
• Time in Patent Office: Days
• US Class Current: 320/116
• CPC Class Codes: G06F 1/263 Arrangements for using multiple switchable power supplies, e.g. battery and AC G06F1/30 takes precedence
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 9/061 for DC powered loads

Abstract

A power distribution system is provided for distributing power in a portable device being coupable to a charging system and including a main battery power and a bridge battery power. The charging system is coupled to a power bus through a diode. The main battery power system and the bridge battery system are also both coupled to the power bus through diodes. The predetermined voltage level is set with respect to the charging system, the main battery and the bridge battery, such that if all three are coupled to the bus, the recharging system both powers the unit and recharges the main battery. If the recharging system is removed, the main battery power system powers the portable device, and if the main battery power system is removed the bridge battery will provide power to the portable device. The distribution system also includes a monitoring system for measuring the predetermined charge level on the battery and disabling a FET switch, so that the main battery stops charging to protect the main battery against overcharging. A monitoring system is also provided for monitoring the voltage level of the main battery utilizing a comparator system.

Claims

1. A power distribution system for a providing power to functional and power circuitry on a portable device, comprising;

a main battery system coupled to a power bus through a first switch system; and

a charging system coupleable to the power bus through a second switch system;

wherein the charging system provides power to the power bus through the second switch system while the charging system is coupled to the second switch system and the main battery system provides power to the power bus through the first switch system upon removal of the charging system.

2. The system of

claim 1

, further including a bridge battery system coupled to the power bus through a third switch system wherein the voltage level of the bridge battery is lower than the voltage level of the main battery and removal of the main battery system and the charging system causes the third switch system to allow the bridge battery system to provide power to the power bus.

3. The system of

claim 1

, wherein the second switch system includes a switch disposed between the main battery system and the power bus, the charging system charging the battery system when the switch is activated and not charging the battery system when the switch is deactivated.

4. The system of

claim 3

, wherein the second switch system includes a main battery diode and the switch coupled in parallel with the main battery diode.

5. The system of

claim 4

, wherein the switch is a FET switch.

6. The system of

claim 3

, further including a charge status monitoring system, the charge status monitoring system monitoring the charge level of the main battery wherein the charging of the main battery is discontinued once the battery meets a predetermined charge level determined by the charge status monitoring system.

7. The system of

claim 6

, wherein the charge status monitor system includes a timer device that causes the charging of the main battery to discontinue after a predetermined amount of time.

8. The system of

claim 7

, wherein the charge status monitor system includes a current measuring device for monitoring the current draw from the charger.

9. The system of

claim 3

, further including a low main battery power monitoring system wherein the low main battery power monitoring system detects a voltage level below a predetermined level of the main battery and outputs a low main battery signal.

10. The system of

claim 9

, wherein the low main battery power monitoring system includes a comparator circuit coupled at a first terminal to the power bus and coupled to a second terminal by a reference signal.

11. The system of

claim 1

, wherein the first switch system is a charger diode.

12. The system of

claim 1

, wherein the second switch system is a main battery diode.

13. A power distribution system for a providing power to functional and power circuitry on a portable device, comprising;

a main battery system coupled to a power bus through a first switch system; and

a bridge battery system coupled to the power bus through a second switch system wherein the voltage level of the bridge battery is lower than the voltage level of the main battery and removal of the main battery system causes the second switch system to allow the bridge battery system to provide power to the power bus.

14. The system of

claim 13

, wherein the first switch system includes a main battery diode.

15. The system of

claim 13

, wherein the second switch system is a bridge battery diode.

16. The system of

claim 13

, further including a charging system coupled to the portable device and the power bus through a third switch system wherein the charging system has a voltage level that is at a predetermined level above a voltage level of the main battery system and the charging system provides power to the power bus through the third switch system when the charger is operating.

17. The system of

claim 16

, wherein the second switch system is a charger diode.

18. The system of

claim 13

, wherein the first switch system includes a switch disposed between the main battery system and the power bus, the charging system charging the battery system when the switch is activated and not charging the battery system when the switch is deactivated.

19. The system of

claim 18

, wherein the first switch system includes a main battery diode and the switch coupled in parallel with the main battery diode.

20. The system of

claim 19

, wherein the switch is a FET switch.

21. The system of

claim 13

, further including a charge status monitoring system, the charge status monitoring system monitoring the charge level of the main battery wherein the charging of the main battery is discontinued once the battery meets a predetermined charge level determined by the charge status monitoring system.

22. The system of

claim 21

, wherein the charge status monitor system includes a timer device that causes the charging of the main battery to discontinue after a predetermined amount of time.

23. The system of

claim 21

, wherein the charge status monitor system includes a current measuring device for monitoring the current draw from the charger.

24. The system of

claim 13

, further including a low main battery power monitoring system wherein the low main battery power monitoring system detects a voltage level below a predetermined level of the main battery and outputs a low main battery signal.

25. The system of

claim 24

, wherein the low main battery power monitoring system includes a comparator circuit coupled at a first terminal to the power bus and coupled to a second terminal by a reference signal.

26. A method for power distribution in a portable device including a power bus coupled to a device power and functional circuitry, comprising the steps of;

providing a main battery system coupled to a power bus through a main battery diode;

providing a charging system coupled to the power bus through a charger diode; and

providing a bridge battery system coupled to the power bus through a bridge battery diode wherein the charging system has a voltage level above the main battery voltage level and the main battery has a voltage level above the bridge battery, such that the charger powers the power bus if the charger is present, the main battery powers the power bus if the charger is not present and the bridge battery powers the bus if the charger and the main battery are not present.

27. The method of

claim 26

, further including the step of recharging the main battery system from the charging system.

28. The method of

claim 26

, further including the step of monitoring the charge level of the main battery and discontinuing the charging of the main battery upon reaching a predetermined charge level.

29. The method of

claim 26

, further including the step of monitoring the voltage level of the main battery and outputting a low battery voltage signal when the voltage level falls below a predetermined level.

30. A power distribution system for a providing power to functional and power circuitry on a portable device, comprising;

means for providing main battery power, the means for providing main battery power including means for coupling the means for providing main battery power to a power bus; and

means for recharging the means for providing main battery power, the means for recharging the means for providing main battery power including means for coupling the means for recharging to a power bus;

wherein the means for charging has a voltage level that is at a predetermined level above a voltage level of the means for providing main battery power causing the means for charging to simultaneously provide power to the power bus and recharge the means for providing main battery power.

31. The system of

claim 30

, further including means for providing power to the power bus in the event the means for providing main battery power is removed, the means for providing power to the power bus in the event the means for providing main battery power is removed including means for coupling the means for providing power to the power bus in the event the means for providing main battery power is removed to the power bus

32. The system of

claim 30

, further including means for monitoring the charge level of the means for providing main battery power.

33. The system of

claim 30

, further including means for monitoring the voltage level of the means for providing main battery power.

34. The system of

claim 30

, further including means for enabling and disabling the recharging of the means for providing main battery power.

35. A power distribution system for a providing power to functional and power circuitry on a portable device, comprising;

a main battery system coupled to a power bus through a main battery diode;

a charging system coupled to the power bus through a charger diode; and

a bridge battery system coupled to the power bus through a bridge battery diode;

wherein the charging system has a voltage level that is at a predetermined level above a voltage level of the main battery system and the voltage level of the bridge battery system is lower than the voltage level of the main battery system, such that if the charging system is present the charger diode is forward biased and the charging system provides power to the power bus, if the charging system is not present the main battery diode becomes forward biased and the main battery system provides power to the power bus and if the charging system and the main battery system are not present the bridge battery diode becomes forward biased and the bridge battery system provides power to the power bus.