DC to DC converter method and circuitry
AssigneeIntersil Corporation
InventorsVolodymyr A. Muratov, Robert G. Hodgins, Thomas A. Jochum
Life of this patent
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Abstract
A DC-to-DC converter has a pulse width modulator PWM) and a hysteretic (ripple) modulator. For low current loads, the hysteretic modulator is selected; for high current loads, the PWM is selected. A mode selection switch senses the polarity of the switched output voltage at the end of each switching cycle. If the polarity changes from one cycle to the next, the mode may be instantly changed to the other mode. Counters are used to record the polarity at the end of each cycle and switching from one mode to another can be delayed by the counters to prevent changing modes based on spurious output voltage fluctuations.
Claims3
A DC-to-DC converter circuit comprising:
- a pulse width modulator controller and a hysteretic controller, each controller for converting a first voltage into a second voltage during a series of repeated switching cycles;
- a mode selection circuit for selecting one of the two controllers in accordance with the current demand of a load coupled to the second voltage;
- a comparator for comparing the second voltage to a reference voltage and generating a polarity signal representative of the second voltage at the end of each switching cycle;
- and
- one or more counters coupled to the comparator and to the mode selection switch for maintaining the mode selection switch in its current mode so long as the polarity of the second voltage at the end of the each cycle is the same as the last n number of cycles and for operating the mode selection switch to select the other controller when the polarity of the second voltage at the end of the cycle changes from the prior cycle and the change in polarity persists for n number of cycles.
Dependencies are inferred from the claim text.