Charging circuit for parallel charging in multiple battery systems
A charging circuit for controlling a system charging parameter provided to a host of rechargeable batteries, wherein the host of batteries includes at least a first battery and second battery that may be coupled in parallel. The charging circuit provides for fast charging of rechargeable batteries in parallel. Independent current and voltage sensing for each battery enables parallel charging of batteries at different charging currents. The charging circuit may be configured to accept either analog or digital signals from an associated power management unit.
1. A power supply system comprising:
a host power management unit configured to execute a power management routine;
a charging circuit for controlling a system charging parameter provided to a plurality of batteries by a DC to DC converter, said charging circuit further comprising:
a first path configured to monitor a first battery charging current provided to a first battery;
a second path configured to monitor a second battery charging current provided to a second battery;
a third path configured to monitor a first battery charging voltage provided to said first battery; and
a fourth path configured to monitor a second battery charging voltage provided to said second battery; and
a regulating circuit configured to reduce said system charging parameter provided to said plurality of batteries by said DC to DC converter if said first battery charging current exceeds a first maximum charging current level or said second battery charging current exceeds a second maximum charging current level, or said first battery charging voltage exceeds a first maximum charging voltage level when said first battery and said second battery are coupled in parallel, or said second battery charging voltage exceeds a second maximum charging voltage level, said first and said second maximum charging current levels and said first and said second maximum charging voltage levels provided to at least one input terminal of said charging circuit by said host power management unit.
2. The charging circuit of claim 1 , wherein said first maximum charging current level is substantially equal to said second maximum charging current level.
3. The charging circuit of claim 1 , wherein said first maximum charging voltage level is substantially equal to said second maximum charging voltage level.
4. The charging circuit of claim 1 , wherein said first path comprises a first error amplifier configured to receive a first monitoring signal representative of said first battery charging current and a first comparison signal representative of said first maximum charging current level, and to provide a first control signal to said regulating circuit based on a difference between said first monitoring signal and said first comparison signal, and wherein said second path comprises a second error amplifier configured to receive a second monitoring signal representative of said second battery charging current and a second comparison signal representative of said second maximum charging current level, and to provide a second control signal to said regulating circuit based on a difference between said second monitoring signal and said second comparison signal, an output of said first and second error amplifiers coupled directly to said regulating circuit, and wherein said first error amplifier controls said regulating circuit if said first error amplifier detects said first charging current is greater than said first maximum charging current level before said second error amplifier detects said second charging current is greater than said second maximum charging current level.
5. A method for controlling a system charging parameter comprising:
providing a control signal to a DC to DC converter by a regulating circuit;
monitoring a first battery charging current provided to a first battery by a first path;
monitoring a second battery charging current provided to a second battery by a second path;
monitoring a first battery charging voltage provided to said first battery by a third path; and
monitoring a second battery charging voltage provided to said second battery by a fourth path; and
reducing said system charging parameter provided to a plurality of batteries by said DC to DC converter that may be coupled in parallel, if said first battery charging current exceeds a first maximum charging current level when said first battery and said second battery are coupled in parallel or said second battery charging current exceeds a second maximum charging current level, or said first battery charging voltage exceeds a first maximum charging voltage level, or said second battery charging voltage exceeds a second maximum charging voltage level, said first and said second maximum charging current levels and said first and said second maximum charging voltage levels provided to at least one input terminal of a charging circuit by a host power management unit.
6. The method of controlling a system charging parameter of claim 5 , wherein said first path comprises a first error amplifier configured to receive a first monitoring signal representative of said first battery charging current and a first comparison signal representative of said first maximum charging current level, and to provide a first control signal to said regulating circuit based on a difference between said first monitoring signal and said first comparison signal, and wherein said second path comprises a second err amplifier configured to receive a second monitoring signal representative of said second battery charging current and a second comparison signal representative of said second maximum charging current level, and to provide a second control signal to said regulating circuit based on a difference between said second monitoring signal and said second comparison signal, an output of said first and said second error amplifiers coupled directly to said regulating circuit, and wherein said first error amplifier controls said regulating circuit if said first error amplifier detects said first charging current is greater than said first maximum charging current level before said second error amplifier detects said second charging current is greater than said second maximum charging current level.
7. The method of claim 5 , wherein said first maximum charging current level is substantially equal to said second maximum charging current level.
8. The method of claim 5 , wherein said first maximum charging voltage level is substantially equal to said second maximum charging voltage level.
9. An electronic device comprising:
a power management unit configured to provide an output signal representative of at least a first maximum charging current level, a second maximum charging current level, a first maximum charging voltage level, and a second maximum charging voltage level;
a charging circuit for controlling a system charging parameter provided to said plurality of batteries by a DC to DC converter, said charging circuit further comprising:
a first path configured to monitor a first battery charging current provided to a first battery and compare said first battery charging current to said first maximum charging current level;
a second path configured to monitor a second battery charging current level provided to a second battery and compare said second battery charging current to said second maximum charging current level;
a third path configured to monitor a first battery charging voltage provided to said first battery and compare said first battery charging voltage to said first maximum charging voltage level; and
a fourth path configured to monitor a second battery charging voltage provided to said second battery and compare said second battery charging voltage to said second maximum charging voltage level; and
a regulating circuit configured to reduce said system charging parameter provided to a plurality of batteries by said DC to DC converter if said first battery charging current exceeds said first maximum charging current level or said second battery charging current exceeds said second maximum charging current level, or said first battery charging voltage exceeds said first maximum charging voltage level, or said second battery charging voltage exceeds said second maximum charging voltage level by said DC to DC converter, said first and said second maximum charging current levels and said first and said second maximum charging voltage levels provided to at least one input terminal of said charging circuit by said power management unit.
10. The electronic device of claim 9 , wherein said output signal from said power management unit comprises an analog signal.
11. The electronic device of claim 9 , wherein said output signal from said power management unit comprises a digital signal.
12. The electronic device of claim 11 , wherein said charging circuit further comprising:
a digital interface configured to receive said digital signal from said power management unit and provide an interface output signal;
a DAC configured to receive said interface output signal and convert said signal to an analog signal representative of said interface output signal; and
a multiplexer to separate said analog signal into a plurality of analog signals representative of at least said maximum charging current level, said second maximum charging current level, said first maximum charging voltage level, and said second maximum charging circuit voltage level.