Abstract: A method and apparatus for controlling a composite battery charger including a switching regulator and a linear charger charging a battery connected to it, whereby the switching regulator provides the supply voltage for the linear charger and Device Circuits. The control method and circuit fully turns on the pass device of the linear charger in a constant current operating mode and the switching regulator is controlled to maintain a constant charge current through the pass device while also supplying device current to the Device Circuits. The device current may vary. The method and circuit limits the dissipation of the pass device of the linear charger by reducing the supply voltage as a function of the charge current in the CC/CV transition region of the battery charger and by reducing the charge current as a function of the battery voltage if the battery voltage is below a predetermined value related to a predetermined minimum supply voltage value.

Abstract: Operational transconductance amplifiers (OTAs) are combined at their outputs, yielding a single frequency compensation connection point. In a preferred embodiment, the output of each OTA is asymmetric, i.e., they can only source current and the OTA outputs are tied together to a constant current sink. Consequently, the OTA that sources more current controls the voltage of the merged output. This merged output point provides a voltage output that may be used as a frequency compensation point.

Abstract: A charge pump controller provides the timing and drive voltages necessary for an self-regulated charge pump voltage converter. The controller utilizes a conventional non-overlapping two-phase clock to control the timing of switch drivers which control an array of switches. Pump and reservoir capacitors are distributed within the array. One of the switch drivers produces a modulated, or linear, drive voltage for one of the switches in the array in response to the charge pump's output voltage. The controller thereby produces a regulated output voltage from the charge pump.

Abstract: A battery charger controller monitors the voltage across an associated battery charger's power element and opens a switch which inhibits current flow through the controller whenever the voltage across the pass element is substantially equal to zero.