US 12,426,139 B1
Feedback control of a diode element
Thomas C. Greening, San Jose, CA (US)
Assigned to Apple Inc., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on Jan. 30, 2023, as Appl. No. 18/103,186.
Claims priority of provisional application 63/355,897, filed on Jun. 27, 2022.
Int. Cl. H05B 45/325 (2020.01)
CPC H05B 45/325 (2020.01) 16 Claims
OG exemplary drawing
 
1. A light source unit, comprising:
a light source configured to emit a first light;
an optical splitter configured to split the emitted first light into a first portion of light and a second portion of light;
a controller configured to:
receive the second portion of light; and
generate a feedback signal using the received second portion of light; and
a driver circuit, comprising a switching converter, the driver circuit configured to:
receive the feedback signal;
generate a first voltage with a duty cycle that varies logarithmically with a voltage change of the feedback signal; and
supply a current based on the first voltage to the light source, wherein:
the driver circuit comprises:
an anti-logarithmic pulse width modulated circuit configured to:
generate a waveform having an anti-logarithmic shape; and
compare the waveform having the anti-logarithmic shape to the feedback signal to generate the first voltage; and
the switching converter receives the first voltage to control a voltage output of the switching converter.