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US 9,072,139 B2Granted
Current driver for LED diodes
AssigneeSTMicroelectronics S.r.l.
InventorsMarco Martini, Salvatore Pantano
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AssigneeSTMicroelectronics S.r.l.
InventorsMarco Martini, Salvatore Pantano
Estimating the term…
A current driver for a string of LEDs includes a first series connection of a first transistor and a first resistance and a second series connection of a second transistor and a second resistance. The first and second series connections are coupled in parallel between the string of LEDs and a voltage reference. An operational amplifier selectively drives the first and second transistors in response to a clock signal. A switch device driven by the clock signal alternately applies a reference voltage and a respective one of the voltages across the first and second resistances to inverting and non-inverting inputs of the operational amplifier in response to the clock signal. A storage circuit is coupled to the output of the operational amplifier to store the drive signals for the first and second transistors for application to the first and second transistors in the absence of output from the operational amplifier.
A current driver for an LED diode having a first terminal coupled to a supply node and having a second terminal, comprising:
A circuit, comprising:
A current driver device for a plurality of series connected LEDs coupled between a supply node and an intermediate node, said current driver device comprising a current driver circuit comprising:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Controlling the intensity of the light: using electrical feedback from LEDs or from LED modules
Details of apparatus for conversion: means for starting or stopping converters
Driver circuits: linear regulators
Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps: semiconductor lamps, e.g. solid state lamps [SSL] light…
About 7 years 3 months of term left · ends 14 Jan 2034 (estimated)
This application claims priority from Italian Application for Patent No. MI2013A000057 filed Jan. 17, 2013, the disclosure of which is incorporated by reference.
The present disclosure relates to a current driver for LED diodes.
It is known in the state of the art for the use of LED array driver devices in applications like displays, information and advertising panels, traffic signals, automotive lighting.
For a better understanding of the present invention, a preferred embodiment thereof is now described, purely by way of non-limiting example and with reference to the annexed drawings, wherein:
FIG. 1 shows a current driver for LED diodes according to prior art;
FIG. 2 shows the circuit in FIG. 1 wherein the effect of the OFFSET voltage is taken into account;
FIG. 3 shows the current driver for an LED diode according to the present disclosure. The current driver in FIG. 3 uses a chopping technique to compensate the offset voltage of the operational amplifier.
The chopping technique is known by the article of C. Enz et al. “A CMOS Chopper Amplifier”, IEEE journal of Solid-State Circuits, vol. sc-22, No. 3, June 1987 and the article of Tao Yin et al. “Noise Analysis and Simulation of Chopper Amplifier”, Circuits and Systems, APCCAS 2006, IEEE Asia Pacific Conference on 4-7 Dec. 2006, pages 167-170 (the disclosures of each of which being incorporated by reference).
The chopping technique consists of using a so called chopper clock to exchange the input voltages at the inverting and non-inverting input terminals of an operational amplifier by means of switches. With this technique the offset voltage of the operational amplifier acts on both the input terminals of the operational amplifier according to the phase of the chopper clock.