US Patent No. 10,251,226

METHOD AND APPARATUS FOR CALCULATING AN AVERAGE VALUE OF AN INACCESSIBLE CURRENT FROM AN ACCESSIBLE CURRENT


Patent No. 10,251,226
Issue Date April 02, 2019
Title Method And Apparatus For Calculating An Average Value Of An Inaccessible Current From An Accessible Current
Inventorship Isaac Cohen, Dix Hills, NY (US)
Assignee TEXAS INSTRUMENTS INCORPORATED, Dallas, TX (US)

Claim of US Patent No. 10,251,226

1. A method for operating a dimmable LED comprising:coupling an LED driver circuit to a rectified output of a dimmer;
providing a current related to an input voltage of the LED driver circuit;
multiplying the value of a reference voltage related to a reference current with a pulse width modulation (PWM) signal having a duty cycle of the LED driver to generate a first voltage, wherein the multiplying includes:
selectively transferring the reference voltage to a multiplication output node based on the PWM signal;
selectively transferring a ground voltage to the multiplication output node based on an inverted version of the PWM signal; and
outputting the first voltage at the multiplication output node;
comparing the first voltage with a second voltage representative of the current through a switch in the LED driver circuit to generate a comparison signal;
using the comparison signal to generate the PWM signal having the duty cycle for controlling the switch and the multiplying.