Abstract: A controller for a DC to DC converter is configured to provide a PWM signal in a first state during a first time interval based on an input voltage less a voltage level representative of an output voltage of the DC to DC converter. The controller may provide the PWM signal in the first state based on the time it takes to charge an energy storage element of the controller to a predetermined level. The controller may also provide an estimator of a zero inductor current level in an associated inductor when the energy storage element is completely discharged. The controller may also be a digital controller that counts time pulses to provide the PWM signal. A DC to DC converter including such a controller and associated methods are also provided.

Abstract: A power management circuit for battery systems composed of a switch defining a single charge/discharge path. The switch is selectively controlled using analog signals to couple a battery to a power source for charging, or to couple the battery to an active load. For charging, the switch is controlled by a controller circuit that monitors the battery voltage, the power source and the individual battery cells. The battery is only coupled to the power source if it is determined that the power source is present and that each of the battery cells is capable of receiving a charge. During discharge, the controller monitors the discharge current from the battery and compares this value to a threshold current. If the discharge current falls below the threshold, the switch is controlled to decouple the battery from the load. In this way, an overcharge condition is avoided if, for example, a power source is reapplied to the system.

Abstract: A balanced battery cell charging circuit is provided. The circuit includes a comparator for comparing the voltage of a battery cell to a predetermined threshold voltage. If the cell voltage exceeds the threshold value, a bleeder current is generated. In one preferred embodiment, the bleeder current is subtracted from the charging current. In another embodiment, the bleeder current is multiplied, and the multiplied bleeder current is subtracted from a total charging current supplied to the cell. To control the charger circuit, current feedback is provided by monitoring the bleeder current generated against a maximum bleeder current, and adjusting the charging current accordingly. The topology of the present invention provides active cell balancing between cells of a battery, and low total power dissipation of the circuit.