Dual-source CMOS battery charger

• US 7,253,589 B1
• Filed: 07/09/2004
• Issued: 08/07/2007
• Est. Priority Date: 07/09/2004
• Status: Active Grant

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Potanina, Elena, Potanin, Vladislav, Vijeh, Khosrow, Dye, Richard
• Primary Examiner(s): Easthom; Karl
• Assistant Examiner(s): BEHM, HARRY RAYMOND
• Application Number:
  US10/888,299
• Time in Patent Office: 1,124 Days
• Field of Search: 320/138, 320/153, 320/144, 320/152, 320/163, 320/164, 307/80, 307/45, 307/52, 323/269, 323/270, 327/534
• US Class Current: 320/138
• CPC Class Codes: H02J 2207/40 adapted for charging from various sources, e.g. AC, DC or multivoltage
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection
• CPC Class Codes: H02J 7/06 using discharge tubes or semiconductor devices
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence
• CPC Class Codes: H02J 7/342 The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging with circuits for polarity protection H02J7/0034

Abstract

A circuit for charging a battery by selecting among two available power sources while providing overcharging and temperature protection to the battery and managing a charging current is described. A power pass and sense circuit is arranged to provide charge voltage from either power source based on control voltages from a current/voltage control circuit, which receives control signals from a logic control and timer circuit, a sensed voltage from a current setting circuit and reference and temperature voltages from a voltage reference and thermo-sense circuit. Differential amplifiers controlling power pass transistors are turned on and off depending on a power source availability and selection. A power supply circuit provides global supply voltages to all subcircuits preventing reverse current to power sources and stable supply independent of a power source availability. A pair of transistors arranged to operate as body-switcher protect power pass and sense transistors against reverse bias current.

Claims

1. A circuit for providing a charge voltage and current to a battery, comprising:

a logic control and timer circuit that is arranged to select at least one of at least two available power source voltages and provide a first and a second control voltages indicating the selection;

a current/voltage control circuit that is arranged to provide one of a first error voltage and a second error voltage in response to the first and second control voltages, such that;

if a first power source voltage is selected, the first error voltage controls, in part, regulation of the charge voltage and current; and

if a second power source voltage is selected, the second error voltage controls, in part, regulation of the charge voltage and current;

a power pass and sense circuit that is arranged to provide the charge voltage and current in response to the selected power source voltage and the corresponding error voltage,

a sense determination circuit that is arranged to receive a portion of the charge voltage, to receive a reference voltage, and to provide a sense voltage; and

a multiplexer that is arranged to multiplex a voltage based on at least one limit current and the portion of the charge voltage, and to provide a feedback voltage, wherein the current/voltage control circuit is arranged to receive the sense voltage, the feedback voltage, a temperature voltage, a reference voltage, and a first enable voltage and a second enable voltage; and

wherein the current/voltage control circuit is further arranged to provide the first error voltage and the second error voltage to the power pass and sense circuit, wherein current/voltage control circuit is further arranged to;

select a smaller of the reference voltage, the temperature voltage, and the sense voltage;

combine the selected voltage with the feedback voltage; and

select at least one of the at least two available power source voltages based on the first and the second enable voltages.

2. The circuit of claim 1, wherein the current/voltage control circuit is arranged to receive at least one digital mode control signal, a plurality of sense voltages, a reference voltage, and the first and second control voltages;

and is further arranged to provide the first and the second error voltages based on the received voltages.

3. The circuit of claim 1, further comprising:

a power supply circuit that is arranged to receive the at least one of at least two available power source voltages and to provide a global supply voltage to the circuit;

a voltage reference and thermo-sense circuit that is arranged to provide a plurality of reference voltages and a temperature dependent voltage to the current/voltage control circuit and to the logic control and timer circuit; and

a current setting circuit that is arranged to receive a sense current and a setting current, and to provide a sense voltage to the current/voltage control circuit such that a regulation of the charge voltage and current is based on a sensed current, the setting current, a temperature of the circuit, and a reference voltage; and

a reconfiguration circuit that is arranged to reconfigure an operation mode of the current/voltage control circuit to a low-voltage-dropout voltage regulation mode, if the battery is disconnected.

4. The circuit of claim 1, wherein the logic control and timer circuit is further arranged to receive a plurality of reference voltages, a setting current, and a portion of the charge voltage and current;

and to determine at least one of a battery charge restart condition, a battery charge status, a battery temperature status, a battery charging current limit, or a power source availability.

5. The circuit of claim 1, wherein the logic control and timer circuit is further arranged to provide a timing signal to at least one other subcircuit.

6. The circuit of claim 1, wherein the logic control and timer circuit is further arranged to provide at least one status signal for external use.

7. The circuit of claim 3, further comprising:

a current source circuit, wherein the current source circuit includes at least one of an external current interface arranged to receive an external current from an external current source or an internal current source, and wherein the current source circuit is arranged to provide the setting current to the current setting circuit; and

a sense resistor, wherein the sense resistor is arranged such that a voltage across the sense resistor is related, in part, to the setting current.

8. The circuit of claim 7, wherein the current source circuit is arranged to receive an input signal and enable the internal current source based upon a state of the input signal.

9. The circuit of claim 4, further comprising:

a sense determination circuit that is arranged to receive a portion of the charge voltage, to receive a reference voltage, and to provide a sense voltage;

a multiplexer that is arranged to multiplex a voltage based on at least one limit current and the portion of the charge voltage, and to provide a feedback voltage, wherein the current/voltage control circuit is arranged to receive the sense voltage, the feedback voltage, a temperature voltage, a reference voltage, and a first enable voltage and a second enable voltage; and

wherein the current/voltage control circuit is further arranged to provide the first error voltage and the second error voltage to the power pass and sense circuit.

10. The circuit of claim 9, wherein current/voltage control circuit is further arranged to:

select a smaller of the reference voltage, the temperature voltage, and the sense voltage;

combine the selected voltage with the feedback voltage; and

select at least one of the at least two available power source voltages based on the first and the second enable voltages.

11. The circuit of claim 1, wherein the current/voltage control circuit further includes:

a minority selection device that is arranged to determine a smaller of the reference voltage, the temperature voltage and the sense voltage;

an operational amplifier that is arranged to combine the feedback voltage and the smaller of the reference voltage, the temperature voltage, and the sense voltage; and

to provide the combined voltage to two differential amplifiers; and

two differential amplifiers, wherein each differential amplifier is arranged to receive power from a body of the power pass and sense circuit, and to provide an error voltage to the power pass and sense circuit; and

wherein the differential amplifiers are selectively enabled based on the first enable voltage and the second enable voltage.

12. A circuit for providing a charge voltage and current to a battery, comprising:

a logic control and timer circuit that is arranged to select at least one of two available power source voltages and provide a first and a second control voltages indicating the selection;

a current/voltage control circuit that is arranged to provide one of a first error voltage and a second error voltage in response to the first and second control voltages, such that;

if a first power source voltage is selected, the first error voltage is provided for regulation of the charge voltage and current; and

if a second power source voltage is selected, the second error voltage is provided for regulation of the charge voltage and current;

a power pass and sense circuit that is arranged to provide the charge voltage and current in response to the selected power source voltage and the corresponding error voltage;

a power supply circuit that is arranged to receive the at least one of two available power source voltages and to provide a global supply voltage to the circuit;

a voltage reference and thermo-sense circuit that is arranged to provide a plurality of reference voltages and a temperature dependent voltage to the current/voltage control circuit and to the logic control and timer circuit;

a current setting circuit that is arranged to receive a sense current and a setting current, and to provide a sense voltage to the current/voltage control circuit such that a regulation of the charge voltage and current is based on a sensed current, the setting current, a temperature of the circuit, and a reference voltage; and

a reconfiguration circuit that is arranged to reconfigure an operation mode of the current/voltage control circuit to a low-voltage-dropout voltage regulation mode, if the battery is disconnected, wherein the setting current is provided by at least one of an internal current source or another current source external to the current setting circuit, and wherein a first variable resistor is employed to determine a value of an internally supplied setting current and a second resistor is employed to determine a value of an externally supplied setting current.

13. The circuit of claim 12, wherein an external signal that is provided to a current selection input indicates if the internally supplied setting current is to be employed for determining a limit of a charging current.

14. The circuit of claim 12, wherein the power pass and sense circuit is further arranged to receive power from at least one of at least two available power source voltages and to provide a sense voltage, wherein the power pass and sense circuit includes:

a power pass transistor that is arranged to receive the power source voltage and provide the charge voltage and current, wherein the power pass transistor has a body;

a power sense transistor that is arranged to receive the power source voltage and provide the sense current, wherein the power sense transistor has a body;

a pair of serially connected body switcher transistors, wherein the pair of serially connected body switcher transistors are coupled in parallel to the power pass transistor, and are arranged to connect the body of the power pass transistor and the body of the power sense transistor to one a power source voltage or the charge voltage, wherein each of the body switcher transistors has a gate;

an inverter that is coupled between the respective gates of the body switcher transistors, and is arranged to control a conduction of the body switcher transistors; and

a level shifter that is arranged to receive a digital power supply voltage and provide a control voltage to the gates of the body switcher transistors such that the transistors are turned on if a reverse bias current from at least one of the at least two power source voltages is present.