Method and system for charge current control

• US 7,436,152 B1
• Filed: 08/28/2003
• Issued: 10/14/2008
• Est. Priority Date: 08/28/2003
• Status: Expired due to Term

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Potanina, Elena, Potanin, Vladislav
• Primary Examiner(s): Berhane; Adolf
• Assistant Examiner(s): Piggush; Aaron
• Application Number:
  US10/652,991
• Time in Patent Office: 1,874 Days
• Field of Search: 320/162, 320/160, 320/152, 320/149, 320/134, 320/130, 320/154
• US Class Current: 320/162
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage

Abstract

A charge current control system is disclosed. One embodiment of the present invention includes a voltage detecting component that determines whether voltage stored by a load is at a voltage threshold. Also included are current supplying components that supply a charge current to the load that attains a plurality of magnitudes. The supply of the charge current is facilitated by a single charge current pass component over the course of a charge cycle. The magnitude of the charge current is based on the outcome of a determination of whether the minimum voltage threshold is reached.

Claims

1. A charge current control system, comprising:

a pass transistor for delivering pre-charge and full-rate magnitude charge current to a load;

a sense resistor coupled to said pass transistor;

a first resistor coupled to said sense resistor;

a second resistor coupled to said sense resistor;

a control amplifier coupled to said sense resistor;

a first controlled current source coupled to said control amplifier and associated with said pre-charge current;

a second controlled current source coupled to said control amplifier and associated with said full rate magnitude charge current; and

a charge control block coupled to said first controlled current source and said second controlled current source,

wherein the magnitude of said pre-charge current is equal to the magnitude of current through said first resistor times the magnitude of the resistance of said first resistor divided by the magnitude of the resistance of said sense resistor and wherein the magnitude of said full-rate charge current is equal to the magnitude of current through said second resistor times the magnitude of the resistance of said second resistor divided by the magnitude of the resistance of said sense resistor.

2. The current control system of claim 1 wherein the supply of said pre-charge and full rate magnitude charge current is facilitated by a single charge current pass component over the course of a charge cycle.

3. The current control system of claim 1 wherein a magnitude of said pre-charge current is determined by a pre-charge circuit block.

4. The current control system of claim 3 wherein a magnitude of said full-rate charge current is determined by a full-rate current control loop.

5. The current control system of claim 1 wherein said sense resistor is located between said pass transistor and said load.

6. A battery charger comprising:

a pass transistor for delivering pre-charge and full-rate magnitude charge current wherein the supply of said charge current at said pre-charge and said full-rate charge is facilitated by a charge current pass component and a single feedback system over the course of a single charge cycle, and wherein a magnitude of said charge current is based on a determination of whether said voltage threshold has been reached;

a sense resistor coupled to said pass transistor;

a first resistor coupled to said sense resistor;

a second resistor coupled to said sense resistor;

a control amplifier coupled to said sense resistor;

a first controlled current source coupled to said control amplifier and associated with said pre-charge current;

a second controlled current source coupled to said control amplifier and associated with said full rate magnitude charge current; and

a charge control block coupled to said first controlled current source and said second controlled current source,

wherein the magnitude of said pre-charge current is equal to the magnitude of current through said first resistor times the magnitude of the resistance of said first resistor divided by the magnitude of the resistance of said sense resistor and wherein the magnitude of said full-rate charge current is equal to the magnitude of current through said second resistor times the magnitude of the resistance of said second resistor divided by the magnitude of the resistance of said sense resistor.

7. The battery charger of claim 6 further comprising a pre-charge circuit which controls said magnitude of said pre-charge current.

8. The battery charger of claim 7 further comprising a full-rate current control loop which controls said magnitude of said full-rate charge current.

9. The battery charger of claim 6 wherein a magnitude of said charge current corresponds to a charge current control state.

10. The battery charger of claim 9 wherein said charge current control state comprises a full-rate state and a pre-charge state.

11. The battery charger of claim 8 wherein current sources that are associated with said pre-charge circuit block and said full-rate current control loop respectively are digitally programmed.