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US 8,525,502 B2Granted
Digital pulse-frequency modulation controller for switch-mode power supplies with frequency targeting and ultrasonic modes
AssigneeExar Corporation
InventorsJason Weinstein, Zhenyu Zhao, Jingquan Chen
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Abstract
A digital pulse controller uses digital logic to send pulses to a high side and low side switches of a switch-mode power supply converter. The digital logic uses a pulse frequency mode which includes a frequency targeting mode and an ultrasonic mode. The frequency targeting mode dynamically adjusts the size of the pulses in order to achieve a switching frequency within a desired band. The ultrasonic mode is switched into when the frequency of the pulses are at or below a threshold and the time of the pulses reaches a minimum threshold.
Claims27
A digital pulse controller comprising:
- digital logic to send pulses to the high side and low side switches of a switch-mode power supply converter, the digital logic allowing for a pulse frequency mode which includes a frequency targeting mode and an ultrasonic mode, the ultrasonic mode being switched into when the frequency of the pulses is at or below a frequency threshold and a total on-time of the pulses reaches a minimum threshold;
- wherein during the frequency targeting mode if the frequency is within an acceptable range, the frequency is adjusted without changing the total on-time of the pulse, and wherein if the frequency is at or below the frequency threshold, but the total on-time is above the minimum threshold the total on time of the pulses is reduced;
- and
- wherein during the ultrasonic mode the total on-time of the pulses is kept fixed at the minimum threshold and the ratio of the high-side pulse on-time to low-side pulse on-time is adjusted to control an output voltage.
1 more element
Dependencies are inferred from the claim text.