Charging Circuit for Parallel Charging in Multiple Battery Systems

Abstract

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 charging control circuit for controlling a system charging parameter provided by a DC to DC converter to a plurality of batteries configured to be coupled in parallel, said charging control circuit further configured to monitor a charging current and a battery charging voltage provided to each of a plurality of batteries; and   a regulating circuit configured to reduce said system charging parameter provided to said plurality of batteries if a first battery charging current exceeds a first maximum charging current level or a second battery charging current exceeds a second maximum charging current level, or a first battery charging voltage exceeds a first maximum charging voltage level, or a second battery charging voltage exceeds a second maximum charging voltage level.   
   
   
       2 . The power supply system of  claim 1  further comprising a host power management unit configured to execute a power management routine, wherein host power management unit is configured to establish said first and said second maximum charging current levels and said first and said second maximum charging voltage levels. 
   
   
       3 . The power supply system of  claim 2  further comprising a selector output circuit configured to provide selector output signals that control selection among a DC power source and said plurality of batteries, said selector output circuit providing said selector output signals in response to a power management unit (PMU) output signal from said PMU. 
   
   
       4 . The power supply system of  claim 3  further comprising a first comparator, said first comparator configured to compare a first signal representative of a voltage level of said DC power source with a first threshold level and provide a DC source enable signal representative of a difference between said first signal and said first threshold level, wherein said selector output circuit is configured to provide selector output signals to select said DC source and deselect said plurality of batteries if said DC source enable signal indicates said voltage level of said DC source is greater than said first threshold level. 
   
   
       5 . The power supply system of  claim 3 , wherein said host power management unit is configured to output a signal representing a desired selection of at least one of said plurality of batteries, and said selector output circuit provides selector output signals to select said DC source and deselect said plurality of batteries if said DC source enable signal indicates said voltage level of said DC source is greater than said first threshold level, thereby overriding said PMU output signal. 
   
   
       6 . The charging circuit of  claim 1 , wherein said first maximum charging current level is substantially equal to said second maximum charging current level. 
   
   
       7 . The charging circuit of  claim 1 , wherein said first maximum charging voltage level is substantially equal to said second maximum charging voltage level. 
   
   
       8 . 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 charging current and a battery charging voltage provided to each of a plurality of batteries configured to be coupled in parallel; and   reducing said system charging parameter provided to a plurality of batteries that may be coupled in parallel, if a first battery charging current exceeds a first maximum charging current level or a second battery charging current exceeds a second maximum charging current level, or a first battery charging voltage exceeds a first maximum charging voltage level, or a second battery charging voltage exceeds a second maximum charging voltage level.   
   
   
       9 . The method of  claim 8  further comprising receiving output signals from a selector output circuit that control selection among a DC power source and said plurality of batteries, said selector output circuit providing said selector output signals in response to a power management unit (PMU) output signal from a host power management unit configured to run a power management routine. 
   
   
       10 . The method of  claim 9  further comprising comparing a first signal representative of a voltage level of said DC power source with a first threshold level and provide a DC source enable signal representative of a difference between said first signal and said first threshold level, wherein said selector output circuit is configured to provide selector output signals to select said DC source and deselect said plurality of batteries if said DC source enable signal indicates said voltage level of said DC source is greater than said first threshold level. 
   
   
       11 . The method of  claim 3 , wherein said host power management unit is configured to output a signal representing a desired selection of at least one of said plurality of batteries, and said selector output circuit provides selector output signals to select said DC source and deselect said plurality of batteries if said DC source enable signal indicates said voltage level of said DC source is greater than said first threshold level, thereby overriding said PMU output signal. 
   
   
       12 . An electronic device comprising:
 a DC to DC converter;   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 control circuit for controlling a system charging parameter provided by said DC to DC converter to said plurality of batteries, said charging control circuit further configured to monitor a charging current and a battery charging voltage provided to each of a plurality of batteries configured to be coupled in parallel; and   a regulating circuit configured to reduce said system charging parameter provided to said plurality of batteries if a first battery charging current exceeds a first maximum charging current level or a second battery charging current exceeds a second maximum charging current level, or a first battery charging voltage exceeds a first maximum charging voltage level, or a second battery charging voltage exceeds a second maximum charging voltage level.   
   
   
       13 . The electronic device of  claim 12  further comprising a selector output circuit configured to provide selector output signals that control selection among a DC power source and said plurality of batteries, said selector output circuit providing said selector output signals in response to a power management unit (PMU) output signal from said PMU. 
   
   
       14 . The electronic device of  claim 13  further comprising a first comparator, said first comparator configured to compare a first signal representative of a voltage level of said DC power source with a first threshold level and provide a DC source enable signal representative of a difference between said first signal and said first threshold level, wherein said selector output circuit is configured to provide selector output signals to select said DC source and deselect said plurality of batteries if said DC source enable signal indicates said voltage level of said DC source is greater than said first threshold level. 
   
   
       15 . The electronic device of  claim 13 , wherein said host power management unit is configured to output a signal representing a desired selection of at least one of said plurality of batteries, and said selector output circuit provides selector output signals to select said DC source and deselect said plurality of batteries if said DC source enable signal indicates said voltage level of said DC source is greater than said first threshold level, thereby overriding said PMU output signal. 
   
   
       16 . The electronic device of  claim 12 , wherein said output signal from said power management unit comprises an analog signal. 
   
   
       17 . The electronic device of  claim 12 , wherein said output signal from said power management unit comprises a digital signal. 
   
   
       18 . The electronic device of  claim 17 , 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.   
   
   
       19 . An electronic device comprising:
 a power management unit (PMU) configured to run a power management routine;   a charging circuit,   a DC to DC converter configured to be coupled to a DC power source;   a selector output circuit configured to provide selector output signals that control selection among a DC power source and a host of rechargeable batteries configured to be coupled in parallel, said selector output circuit providing said selector output signals in response to a power management unit (PMU) output signal from said PMU;   a charging control circuit configured to control charging of said host of rechargeable batteries, said charging control circuit further configured to monitor a charging current and a battery charging voltage provided to each of a plurality of said host of batteries; and   a regulating circuit configured to reduce said system charging parameter provided to said plurality of batteries if a first battery charging current exceeds a first maximum charging current level or a second battery charging current exceeds a second maximum charging current level, or a first battery charging voltage exceeds a first maximum charging voltage level, or a second battery charging voltage exceeds a second maximum charging voltage level.   
   
   
       20 . The electronic device of  claim 14 , wherein said charging circuit and said selector circuit are integrated onto one integrated circuit.