Method and apparatus for current limiting of an output of a DC-to-DC converter
AssigneeSigmatel, Inc.
InventorMarcus W. May
Life of this patent
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Abstract
A method for current limiting of an output of a DC-to-DC converter begins by determining a current loading duty cycle of the output of the DC-to-DC converter (i.e., the present duty cycle given the loading of on the output). The processing then continues by comparing the current loading duty cycle with a zero loading duty cycle of the output (i.e., the duty cycle when the output has no load). The processing continues by limiting duty cycle of the output to the zero loading duty cycle plus a duty cycle loading offset when the current loading duty cycle exceeds the zero loading duty cycle plus the duty cycle loading offset.
Claims16
A method for current limiting in a DC-to-DC converter, the method comprises:
- determining a current loading duty cycle of the DC-to-DC converter;
- comparing the current loading duty cycle with a zero loading duty cycle of the output;
- and
- when the current loading duty cycle exceeds the zero loading duty cycle plus a duty cycle loading offset, limiting duty cycle of the DC-to-DC converter to the zero loading duty cycle plus the duty cycle loading offset.
A method for current limiting a DC-to-DC converter, the method comprises:
- monitoring duty cycle of the DC-to-DC converter to produce a monitored duty cycle;
- equating the monitored duty cycle to an inductor current based on a relationship between the inductor current and the duty cycle of the DC-to-DC converter to produce an equated current;
- comparing the equated current with a current limit threshold;
- and
- when the equated current compares unfavorably with the current limit threshold, limiting the inductor current based on the current limit threshold.
An on-chip DC-to-DC converter comprises:
- a regulation module operably coupled to produce a regulation signal;
- output capacitance operably coupled to the first output;
- an integrated circuit (IC) pad for coupling to an external inductor;
- an output stage operably coupled to the output capacitance, the IC pad, and the regulation module to produce an output based on the regulation signal, wherein the regulation module provides current limiting of the output by:
- determining a current loading duty cycle of an output of the DC-to-DC converter;
- comparing the current loading duty cycle with a zero loading duty cycle of the output;
- and
- when the current loading duty cycle exceeds the zero loading duty cycle plus a duty cycle loading offset, limiting duty cycle of the output to the zero loading duty cycle plus the duty cycle loading offset.
The DC-to-DC converter of claim 11, wherein the regulation module further functions to:
- equating the zero loading duty cycle to
- 5 Vout - Vbat Vout ,
- where Vout represents voltage of the output and Vbat represents voltage of a battery.
An on-chip DC-to-DC converter comprises:
- a regulation module operably coupled to produce a regulation signal;
- output capacitance operably coupled to the first output;
- an integrated circuit (IC) pad for coupling to an external inductor;
- an output stage operably coupled to the output capacitance, the IC pad, and the regulation module to produce an output based on the regulation signal, wherein the regulation module provides current limiting of the output by:
- monitoring duty cycle of an output of the DC-to-DC converter to produce a monitored duty cycle;
- equating the monitored duty cycle to an inductor current based on a relationship between the inductor current and the duty cycle for the output of the DC-to-DC converter to produce an equated current;
- comparing the equated current with a current limit threshold;
- and
- when the equated current compares unfavorably with the current limit threshold, limiting the inductor current based on the current limit threshold.
Dependencies are inferred from the claim text.