Load side method of blocking charger voltage from a battery load

• US 10,103,556 B2
• Filed: 11/17/2015
• Issued: 10/16/2018
• Est. Priority Date: 11/17/2015
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola Solutions, Inc.
• Inventors: Snyder, Robert L., Bin Azizan, Muhamad Ridzuan, Boyer, Roger L., Flowers, Donald L.
• Primary Examiner(s): Nguyen, Danny
• Application Number:
  US14/944,002
• Publication Number:
  US 20170141592A1
• Time in Patent Office: 1,064 Days
• Field of Search: 361 86- 87, 361 937- 939, 320134, 320136
• CPC Class Codes: H02H 3/08 responsive to excess current responsive to abnormal temperature caused by excess current H02H5/04
• CPC Class Codes: H02H 3/087 for dc applications
• CPC Class Codes: H02H 3/20 responsive to excess voltage
• CPC Class Codes: H02H 3/202 for dc systems
• CPC Class Codes: H02H 7/18 for batteries; for accumulators
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 7/0042 characterised by the mechanical construction

Abstract

Methods and apparatus for a protection circuit for a battery and a battery connected device during charging are provided. In one embodiment, the apparatus includes a load-blocking switch connected between a rechargeable battery and an electronic device and a charge-blocking switch connected between the rechargeable battery and a charger. The apparatus also includes a safety circuit to detect a voltage across and the current flowing through the rechargeable battery. The safety circuit opens the load-blocking switch and the charge-blocking switch when it detects that the voltage across or the current flowing through the battery exceeds a predetermined threshold.

Claims

1. A protection circuit for an electronic device having a rechargeable battery, the protection circuit comprising:

a load path between a first node and a second node and including a load of the electronic device;

a cell path between the first node and the second node and including a battery cell of the rechargeable battery, wherein the cell path is parallel to the load path;

a load-blocking switch electrically connected in the load path;

a charge-blocking switch electrically connected in the cell path;

a safety circuit electrically connected to the rechargeable battery, the load-blocking switch, and the charge-blocking switch, wherein the safety circuit monitors an electrical parameter of the rechargeable battery, wherein the safety circuit further opens the load-blocking switch and opens the charge-blocking switch upon detecting that the electrical parameter exceeds a predetermined threshold; and

a level shifter electrically connected between the safety circuit, the load-blocking switch and the charge-blocking switch.

2. The protection circuit of claim 1, wherein the electrical parameter is a voltage across the rechargeable battery.

3. The protection circuit of claim 1, wherein the electrical parameter is a current flowing through the rechargeable battery.

4. The protection circuit of claim 1, wherein the load-blocking switch is electrically connected between a positive terminal of the rechargeable battery and a positive terminal of the electronic device.

5. The protection circuit of claim 1, wherein the load-blocking switch is electrically connected between a negative terminal of the rechargeable battery and a negative terminal of the electronic device.

6. The protection circuit of claim 1, further comprising a resistor electrically connected across the load-blocking switch, wherein when the rechargeable battery is in an over-charged condition a discharge path is provided from the rechargeable battery through the resistor.

7. The protection circuit of claim 4, wherein the load-blocking switch includes a P channel field effect transistor.

8. The protection circuit of claim 5, wherein the load-blocking switch includes a N channel field effect transistor.

9. The protection circuit of claim 1, further comprising a delay circuit electrically connected between the level shifter and the charge-blocking switch for providing a delay between opening the load-blocking switch and opening the charge-blocking switch.

10. The protection circuit of claim 1, further comprising an inverter circuit electrically connected between the level shifter and the load-blocking switch.

11. The protection circuit of claim 1, further comprising:

a discharge-blocking switch electrically connected between the charger and the rechargeable battery;

a thermistor connected to the rechargeable battery and the discharge-blocking switch for monitoring a temperature of the rechargeable battery, wherein the thermistor opens the discharge-blocking switch when the temperature of the rechargeable battery exceeds a predetermined threshold.

12. A method of protecting an electronic device connected to a rechargeable battery, the method comprising:

providing a load path between a first node and a second node, the load path including a load of the electronic device;

providing a cell path between the first node and the second node, the cell path including a battery cell of the rechargeable battery and being parallel to the load path;

electrically connecting a load-blocking switch in the load path;

electrically connecting a charge-blocking switch in the cell path;

detecting, with a safety circuit, an electrical parameter of the rechargeable battery;

opening the load-blocking switch and the charge-blocking switch when the electrical parameter exceeds a threshold value; and

providing a discharge-blocking switch between the charger and the rechargeable battery;

monitoring, with a thermistor, a temperature of the rechargeable battery; and

opening the discharge-blocking switch when the temperature exceeds a predetermined threshold.

13. The method of claim 12, wherein the electrical parameter is a voltage across the rechargeable battery.

14. The method of claim 12, wherein the electrical parameter is a current flowing through the rechargeable battery.

15. The method of claim 12, further comprising delaying opening the charge-blocking switch by a predetermined amount of time after opening the load-blocking switch.

16. The method of claim 12, further comprising electrically connecting a level shifter between the safety circuit, the load-blocking switch and the charge-blocking switch.

17. The method of claim 12, further comprising:

detecting that the rechargeable battery is in an over-charged condition; and

providing a discharge path to the rechargeable battery through a resistor electrically connected across the load-blocking switch.

18. A protection circuit for an electronic device having a rechargeable battery, the protection circuit comprising:

a load path between a first node and a second node and including a load of the electronic device;

a cell path between the first node and the second node and including a battery cell of the rechargeable battery, wherein the cell path is parallel to the load path;

a load-blocking switch electrically connected in the load path;

a charge-blocking switch electrically connected in the cell path;

a safety circuit electrically connected to the rechargeable battery, the load-blocking switch, and the charge-blocking switch, wherein the safety circuit monitors an electrical parameter of the rechargeable battery, wherein the safety circuit further opens the load-blocking switch and opens the charge-blocking switch upon detecting that the electrical parameter exceeds a predetermined threshold;

a discharge-blocking switch electrically connected between the charger and the rechargeable battery; and

a thermistor connected to the rechargeable battery and the discharge-blocking switch for monitoring a temperature of the rechargeable battery, wherein the thermistor opens the discharge-blocking switch when the temperature of the rechargeable battery exceeds a predetermined threshold.

19. A method of protecting an electronic device connected to a rechargeable battery, the method comprising:

providing a load path between a first node and a second node, the load path including a load of the electronic device;

providing a cell path between the first node and the second node, the cell path including a battery cell of the rechargeable battery and being parallel to the load path;

electrically connecting a load-blocking switch in the load path;

electrically connecting a charge-blocking switch in the cell path;

detecting, with a safety circuit, an electrical parameter of the rechargeable battery;

opening the load-blocking switch and the charge-blocking switch when the electrical parameter exceeds a threshold value; and

delaying opening the charge-blocking switch by a predetermined amount of time after opening the load-blocking switch.

20. A method of protecting an electronic device connected to a rechargeable battery, the method comprising:

providing a load path between a first node and a second node, the load path including a load of the electronic device;

providing a cell path between the first node and the second node, the cell path including a battery cell of the rechargeable battery and being parallel to the load path;

electrically connecting a load-blocking switch in the load path;

electrically connecting a charge-blocking switch in the cell path;

detecting, with a safety circuit, an electrical parameter of the rechargeable battery;

opening the load-blocking switch and the charge-blocking switch when the electrical parameter exceeds a threshold value; and

electrically connecting a level shifter between the safety circuit, the load-blocking switch and the charge-blocking switch.