Methods and apparatus for voltage and current calibration

1. A calibration circuit for calibrating a battery pack having a negative pack terminal and a negative battery terminal and a protection IC comprising a first terminal and a second terminal, comprising:

a power source configured to provide a predetermined voltage and selectively coupled to the protection IC and capable of providing a current to the protection IC through one of a first current loop and a second current loop;

wherein:

the current through the first current loop generates a first voltage across the first and second terminals; and

the current through the second current loop generates a second voltage across the first and second terminals that is substantially equal to the voltage of the power source.

2. The calibration circuit according to claim 1 , further comprising a first switching device to selectively couple the power source to the protection IC.

3. The calibration circuit according to claim 2 , wherein the first switching device is configured to select between the first current loop and the second current loop.

4. The calibration circuit according to claim 1 , wherein the second current loop comprises a sense resistor coupled between the power source and the second terminal of the protection IC.

5. The calibration circuit according to claim 4 , wherein the first current loop bypasses the sensor resistor.

6. The calibration circuit according to claim 1 , further comprising a current source coupled between the negative pack terminal and the negative battery terminal to form a third current loop through the battery pack.

7. The calibration circuit according to claim 6 , further comprising a switchable bypass controlled by a second switching device current loop coupled to the current source, wherein current flows through the bypass current loop and bypasses the battery pack.

8. A method for calibration of a protection IC coupled to a power supply, a current source, and a transistor, comprising:

initializing the protection IC, comprising:

selectively coupling the power source to the protection IC through one of a first current loop and a second current loop; and

trimming data bits, comprising:

selectively coupling the current source to the protection IC through a third current loop;

determining the transistor operating state;

setting a current data bit to one of a high value and a low value based on the operating state;

determining a binary position of the current data bit;

selectively coupling the current source to a bypass loop, wherein the bypass loop bypasses the protection IC; and

setting a subsequent bit to the high value.

9. The method for calibration according to claim 8 , wherein initializing the protection IC further comprises:

coupling the power source to the protection IC through the first current loop; and

coupling the current source to the bypass loop.

10. The method for calibration according to claim 8 , wherein initializing the protection IC further comprises:

coupling the power source to the protection IC through the second current loop; and

coupling the current source to the bypass loop.

11. The method for calibration according to claim 8 , wherein initializing the protection IC further comprises applying a test signal to the protection IC from a pulse generator coupled to the protection IC when the current source is coupled to the bypass loop.

12. The method for calibration according to claim 8 , wherein the second current loop comprises a sense resistor coupled between the power source and the second terminal of the protection IC.

13. The method for calibration according to claim 10 , wherein trimming data bits comprises an iterative process for each of the plurality of bits.

14. A calibration system, comprising:

a battery pack comprising a protection IC comprising a first terminal and a second terminal;

a power source, having a predetermined voltage, selectively coupled to the protection IC and capable of providing a current to the protection IC through one of a first current loop and a second current loop;

a current source coupled between the negative pack terminal and the negative battery terminal to form a third current loop through the battery pack;

a pulse generator coupled to the protection IC and capable of providing a test signal to the protection IC;

wherein:

current through the first current loop generates a first voltage across the first and second terminals; and

current through the second current loop generates a second voltage across the first and second terminals that is substantially equal to the voltage of the power source.

15. The calibration system of claim 14 , further comprising a first switching device to selectively couple the power source to the protection IC.

16. The calibration system of claim 14 , wherein the second current loop comprises a sense resistor coupled between the power source and the second terminal of the protection IC.

17. The calibration system of claim 16 , wherein the first current loop bypasses the sense resistor and directly couples the second terminal of the protection IC to the power source.

18. The calibration system of claim 14 , further comprising a switchable bypass controlled by a second switching device current loop coupled to the current source, wherein current flows through the bypass current loop and bypasses the battery pack.

19. The calibration system of claim 14 , further comprise a third terminal configured to calibrate the current of the protection IC.

20. The calibration system of claim 14 , wherein the power source, the current source, and the pulse generator are disposed exterior of the battery pack.