Patent ID: 8269465

Claim:
A circuit for charging a battery, comprising: a microprocessor configured to receive a current sense signal and a voltage sense signal, the microprocessor further configured to generate control signals for selectively operating the circuit for charging the battery in a charging mode and a maintenance mode; a current sense circuit configured to measure the battery's current consumption and generate the current sense signal responsive to the measured current consumption; a voltage sense circuit configured to measure the battery's voltage and generate the voltage sense signal responsive to the measured battery voltage; a waveform generator circuit configured to receive the control signals, and operate in response thereto to apply a charging signal to the battery when in the charging mode and to deactivate the charging signal when in the maintenance mode; and a monitoring circuit configured in the maintenance mode to monitor a settling voltage of the battery in the absence of the charging signal, wherein the charging signal has an oscillating sawtooth current waveform superimposed on a DC bias; and wherein the oscillating sawtooth current waveform is characterized by a plurality of consecutive current pulses, each current pulse having a rise portion and a fall portion, wherein the fall portion of each current pulse comprises a first linear portion having a first slope followed by a second linear portion having a second slope different from the first slope, and wherein linearity for the second slope of the second linear portion is consistent from pulse to pulse in the sawtooth current waveform.