US 12,464,619 B2
Light emitting diode (LED) current regulator circuit with multiple LED pins for robust control of LED chain
Maurizio Galvano, Padua (IT); Mattia Montoncelli, Abano Terme (IT); Enrico Tonazzo, Villanova di Camposampiero (IT); and Yoshinori Imanaka, Yokohama (JP)
Assigned to Infineon Technologies AG, Neubiberg (DE)
Filed by Infineon Technologies AG
Filed on May 2, 2023, as Appl. No. 18/311,022.
Prior Publication US 2024/0373530 A1, Nov. 7, 2024
Int. Cl. H05B 45/44 (2020.01)
CPC H05B 45/44 (2020.01) 15 Claims
OG exemplary drawing
 
1. A circuit configured to deliver current to a plurality of light emitting diodes (LEDs) arranged in series, the circuit comprising:
a first LED pin on a first supply side of the circuit, wherein the first LED pin is configured to be connected to the plurality of LEDs arranged in series;
a second LED pin on the first supply side of the circuit, wherein the second LED pin is configured to be connected to a subset of the plurality of LEDs, wherein the subset comprises a portion of the plurality of LEDs; and
a third pin on a second supply side of the circuit,
wherein the circuit is configured to:
deliver a first current to the plurality of LEDs through the first LED pin and over a first current path through the circuit, wherein the first current path includes a first transistor; and
deliver a second current to the subset of the plurality of LEDs through the second LED pin and over a second current path through the circuit, wherein the second current path includes a second transistor, wherein the second current path is in parallel with the first current path in the circuit, and wherein a sum of the first current and the second current is regulated based on a sensed current through the circuit, wherein regulation of the first current path and the second current path comprises a single regulation loop by the circuit, wherein to perform the single regulation loop, the circuit includes:
an operational amplifier configured to generate a main control signal for regulating both the first current path and the second current path based on the sensed current and a voltage reference signal, wherein the main control signal defines a first control signal for the second transistor; and
a second amplifier that includes a single input connected to an output of the operational amplifier, wherein the second amplifier is configured to receive the output of the operational amplifier as the single input to the second amplifier and automatically generate a second control signal for the first transistor based on the output of the operational amplifier and a pre-defined function, wherein the pre-defined function is based on a voltage headroom associated with the first current path.