Emulated current ramp for DC-DC converter
AssigneeTexas Instruments Incorporated
InventorSong Guo
Life of this patent
Estimating the term…
Abstract
A voltage converter (FIG. 4) for a power supply circuit is disclosed. The voltage converter comprises a control circuit (400) coupled to receive an enable (EN) signal. The control circuit produces a first control signal (PWM) to provide a load current (IL) in response to the enable signal. A sample and hold circuit (408) is arranged to produce a third control signal (CSP) to emulate the load current and a fourth control signal (CSN′) to sample and hold value of the third control signal. A comparator circuit (416) is arranged to compare the third and fourth control signals and produce the enable signal in response to a result of the comparison.
Claims20
A voltage converter, comprising:
- a control circuit coupled to receive an enable signal, the control circuit producing a first control signal to activate a switch to provide a load current to an output terminal in response to the enable signal;
- an inductor in series with an output of the voltage converter;
- a second order filter in parallel with the inductor, the second order filter comprising a plurality of first-order filters, each of first-order filters having a capacitor coupled to the output of the voltage converter;
- a sample and hold circuit coupled to a node of one of the plurality of first order filters to receive a third control signal at an input thereof to emulate the load current and generate a fourth control signal at an output of the sample and hold circuit as a new value of the third control signal;
- and
- a comparator circuit arranged to compare the third and fourth control signals and produce the enable signal in response to a result of the comparison.
A power supply, comprising:
- a first output transistor having a first control terminal and having a current path coupled between a supply voltage and an output terminal;
- a second output transistor having a second control terminal and having a current path coupled between the output terminal and a reference terminal;
- a control circuit coupled to receive an enable signal, the control circuit producing a first control signal at the first control terminal in response to the enable signal, and producing a second control signal at the second control terminal;
- a sample and hold circuit arranged to produce a third control signal at an input thereof to emulate a load current and generate a fourth control signal at an output of the sample and hold circuit as a new value of the third control signal;
- and
- a comparator circuit arranged to compare the third and fourth control signals and produce the enable signal in response to a result of the comparison.
A method of regulating an output voltage, comprising:
- producing an on-time signal having a first duration in response to an enable signal;
- producing a load current in response to the on-time signal;
- producing a first voltage signal emulating the load current in a second order filter;
- producing a second voltage signal having a sampled value of the first voltage signal at a valley thereof and holding the sampled signal during the next cycle;
- filtering the second voltage signal;
- comparing the first and second voltage signals;
- and
- producing the enable signal in response to a result of the step of comparing.
Dependencies are inferred from the claim text.