Cradle charger controller with below ground level biasing

• US 7,830,115 B2
• Filed: 09/17/2007
• Issued: 11/09/2010
• Est. Priority Date: 04/13/2007
• Status: Expired due to Fees

• Current Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Original Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Inventors: Wong, Chuck
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): OMAR, AHMED H
• Application Number:
  US11/856,513
• Publication Number:
  US 20080252252A1
• Time in Patent Office: 1,149 Days
• Field of Search: 363/81, 363/84, 363/125, 320/152, 320/160, 320/108
• US Class Current: 320/108
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/46 Accumulators structurally combined with charging apparatus circuits for charging H02J7/00
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A cradle charging system comprises a charging cradle defining a space for a battery of an electronic device. Transformer charging circuitry for charging the battery in the electronic device includes a primary side circuitry for receiving a charging voltage. Secondary side circuitry inductively couples the charging voltage to the battery. The secondary side circuitry provides a controlled output signal based on either constant voltage control or constant current control responsive to a charge level of the battery.

Claims

1. A cradle charging system, comprising:

a charging cradle defining a space for receiving a battery of an electronic device;

a transformer charging circuitry for charging the battery in the electronic device, the transformer charging circuitry further comprising;

primary side circuitry for receiving a charging voltage;

secondary side circuitry for inductively coupling the charging voltage to the battery, wherein the secondary side circuitry provides a controlled output signal based on either constant voltage control or constant current control responsive to a charge level of the battery, wherein the secondary side circuitry has a negative voltage for a ground reference, wherein the secondary side circuitry has a negative voltage for a ground reference; and

a control circuit for generating the controlled output signal responsive to at least one of a sensed charging voltage to the battery and a sensed charging current to the battery, wherein the control circuit generates a voltage control signal as the controlled output signal responsive to the sensed charging voltage and a reference voltage in a first mode of operation and wherein the control circuit generates a current control signal as the controlled output signal responsive to the sensed charging current and the reference voltage in a second mode of operation.

2. The cradle charging system of claim 1, wherein the secondary side circuitry further includes a control circuit for generating the controlled output signal responsive to either a monitored charging voltage of the battery or a monitored charging current of the battery.

3. The cradle charging system of claim 2, wherein the control circuit further generates the controlled output signal responsive to a battery control signal indicating whether the battery is a one cell or a two cell battery.

4. The cradle charging system of claim 2, further including an opto-isolator circuit for linking the controlled signal from the secondary side circuitry to the primary side circuitry.

5. The cradle charging system of claim 2, wherein the control circuit further generates a status signal indicating a charging state of the battery.

6. The cradle charging system of claim 2, wherein the control circuit further controls a gain of the monitored charging voltage.

7. The cradle charging system of claim 1, wherein the secondary side circuitry further includes a rectifier circuit to generate a negative voltage with respect to a negative battery terminal of the secondary side circuitry to provide the negative voltage for the ground reference.

18. The cradle charging system of claim 1, wherein a first number of battery cells enables the first mode of operation and a second number of battery cells enables the second mode of operation.

8. A cradle charging system, comprising:

a charging cradle defining a space for receiving a battery of an electronic device;

a transformer charging circuitry for charging the battery in the electronic device, the transformer charging circuitry further comprising;

primary side circuitry for receiving a charging voltage;

secondary side circuitry for inductively coupling the charging voltage to the battery, wherein the secondary side circuitry provides a controlled output signal based on either constant voltage control or constant current control responsive to a charge level of the battery wherein the secondary side circuitry has a negative voltage for a ground reference; and

a control circuit for generating the controlled output signal responsive to a battery control signal indicating whether the battery is a one cell or a two cell battery and to either a monitored charging voltage of the battery or a monitored charging current of the battery, the control circuit further comprising;

a first differential amplifier for sensing an output voltage to the battery;

a second differential amplifier for sensing an output current to the battery;

a first error amplifier for generating a voltage control signal responsive to the sensed output voltage of the first differential amplifier and a reference voltage;

a second error amplifier for generating a current control signal responsive to the sensed output current of the second differential amplifier and the reference voltage;

a first output driver for outputting the voltage control signal as the controlled output signal responsive to an enable signal at a first logical level;

a second output driver for outputting the current control signal as the controlled output signal responsive to the enable signal at the second logical level, and

control logic for generating the enable signal at the second logical level when the output voltage is below a predetermine level and at the first logical level when the output voltage is above the predetermined level, wherein the predetermined level is established responsive to the battery control signal.

9. The cradle charging system of claim 8, further including an opto-isolator circuit for linking the controlled signal from the secondary side circuitry to the primary side circuitry.

10. The cradle charging system of claim 8, wherein the control logic further generates a status signal indicating a charging state of the battery.

11. The cradle charging system of claim 8, wherein the control logic further controls a gain of the first differential amplifier.

12. The cradle charging system of claim 8, wherein the secondary side circuitry further includes a rectifier circuit to generate a negative voltage with respect to a negative battery terminal of the secondary side circuitry to provide the negative voltage for the ground reference.

13. A method for charging a battery using a cradle charger circuit, comprising the steps of:

monitoring a charging voltage applied to the battery;

monitoring a charging current applied to the battery;

generating a voltage control signal responsive to the monitored charging voltage and a reference voltage;

generating a current control signal responsive to the monitored charging current and a reference voltage;

outputting the voltage control signal as a control signal to a primary side of cradle charger circuit when the charging voltage is above a predetermined level;

outputting the current control signal as the control signal to the primary side of cradle charger circuit when the charging voltage is below the predetermined level;

controlling charging of the battery responsive to the control signal; and

generating a negative voltage for a ground reference with respect to a negative battery terminal of a second side circuitry of a transformer circuit.

14. The method of claim 13, wherein the step of controlling further includes the step of linking the control signal from a secondary side circuitry of a transformer to the primary side circuitry of the transformer.

15. The method of claim 13, further including the step of generating a status signal indicating a charging state of the battery.

16. The method of claim 13, further including the step of controlling a gain of the monitored charging voltage.

17. The method of claim 13 further including the step of establishing the predetermined level responsive to an indication of a number of cells of the battery.

19. A control chip for controlling a secondary side of a transformer charging circuit, comprising:

a battery voltage input for receiving a sensed charging voltage of a battery being charged by the transformer charging circuit;

at least one current input for receiving a sensed charging current to the battery being charged by the transformer charging circuit;

at least one control output for providing a controlled output signal;

a control circuit for generating the controlled output signal to control the secondary side of a transformer charging circuit, the secondary side having a negative voltage for a ground reference, responsive to at least one of the sensed charging voltage to the battery and the sensed charging current to the battery, wherein the control circuit generates a voltage control signal as the controlled output signal responsive to the sensed charging voltage and a reference voltage in a first mode of operation and wherein the control circuit generates a current control signal as the controlled output signal responsive to the sensed charging current and the reference voltage in a second mode of operation.

20. The control chip of claim 19, wherein the control circuit further generates the controlled output signal responsive to a battery control signal indicating whether the battery is a one cell or a two cell battery.

21. The control chip of claim 19, wherein the control circuit further generates a status signal indicating a charging state of the battery.

22. The control chip of claim 19, wherein the control circuit further controls a gain of the monitored charging voltage.