US 2019/0379270 A1 · LOSSLESS AVERAGE INPUT AND OUTPUT CURRENT SENSING IN A SWITCHED-MODE POWER SUPPLY

Abstract

Methods and apparatus for current sensing and error correction in a switched-mode power supply composed of a high-side transistor coupled to a low-side transistor are described. One example method generally includes capturing a current associated with the low-side transistor at a first time corresponding to the low-side transistor turning off; capturing a current associated with the high-side transistor at a second time corresponding to a first delay after the high-side transistor turns on; capturing the current associated with the high-side transistor at a third time corresponding to the high-side transistor turning off; and applying a first correction current to a current-summing node of the current-sensing circuit for a first interval based on the first delay, wherein the first correction current is based on the captured current associated with the low-side transistor at the first time and on the captured current associated with the high-side transistor at the second time.

Claims20

Dependent claims

A method of current sensing and correction for a switched-mode power supply comprising a high-side transistor and a low-side transistor coupled to the high-side transistor, the method comprising:

capturing, with a current-sensing circuit, a current associated with the low-side transistor at a first time corresponding to the low-side transistor turning off;
capturing a current associated with the high-side transistor at a second time corresponding to a first delay after the high-side transistor turns on;
capturing the current associated with the high-side transistor at a third time corresponding to the high-side transistor turning off;
and
applying a first correction current to a current-summing node of the current-sensing circuit for a first interval based on the first delay, wherein the first correction current is based on the captured current associated with the low-side transistor at the first time and on the captured current associated with the high-side transistor at the second time.

2 more elements

A current-sensing circuit for a switched-mode power supply comprising a high-side transistor and a low-side transistor coupled to the high-side transistor, the current-sensing circuit comprising:

a high-side current-sensing amplifier having an input for coupling to the high-side transistor;
a low-side current-sensing amplifier having an input for coupling to the low-side transistor;
a first sample-and-hold circuit coupled to an output of the low-side current-sensing amplifier and configured to capture a current associated with the low-side transistor at a first time corresponding to the low-side transistor turning off;
a second sample-and-hold circuit coupled to an output of the high-side current-sensing amplifier and configured to capture a current associated with the high-side transistor at a second time corresponding to a first delay after the high-side transistor turns on;
a third sample-and-hold circuit coupled to the output of the high-side current-sensing amplifier and configured to capture the current associated with the high-side transistor at a third time corresponding to the high-side transistor turning off;
a first voltage-to-current converter having an input coupled to an output of the first sample-and-hold circuit and to an output of the second sample-and-hold circuit;
a first switch coupled between an output of the high-side current-sensing amplifier and a sensing node for the current-sensing circuit;
and
a second switch coupled between an output of the first voltage-to-current converter and the sensing node.

6 more elements

Dependencies are inferred from the claim text.

Lossless average input and output current sensing in a switched-mode power supply

Life of this patent

Lossless average input and output current sensing in a switched-mode power supply

Life of this patent

Abstract

Claims20