Current supply system, related integrated circuit, power supply system and method of operating a current supply system

Patent metadata

Field	Value
Publication number	US-11483909-B2
Application number	US-202117523641-A
Country	US
Kind code	B2
Filing date	Nov 10, 2021
Priority date	Nov 17, 2020
Publication date	Oct 25, 2022
Grant date	Oct 25, 2022

Abstract

A control circuit for a voltage source generates a reference signal for a voltage source, wherein the reference signal indicates a requested output voltage to be generated by the voltage source. A digital feed-forward control circuit computes a digital feed-forward regulation value indicative of a requested output voltage by determining a maximum voltage drop at strings of solid-state light sources. A digital feed-back control circuit determines a minimum voltage drop for current regulators/limiters for the strings and determines a digital feed-back correction value as a function of the minimum voltage drop. The control circuit then sets the reference signal after a start-up as a function of the digital feed-forward regulation value and corrects the reference signal as a function of the digital feed-back correction value.

First claim

The invention claimed is:

1. A current supply system, comprising:
one or more first terminals configured to be connected to a first output terminal of a voltage source;
a plurality of second terminals, wherein each of said second terminals is configured to be connected via a respective string of solid-state light sources to a second output terminal of said voltage source;
a third terminal configured to provide a reference signal to said voltage source, said reference signal indicative of a requested output voltage to be generated by said voltage source between said first and said second output terminals of said voltage source;
a plurality of current regulators or limiters, wherein each of said second terminals is connected via a respective current regulator or limiter to at least one of said one or more first terminals, wherein each of said current regulators or limiters is configured to limit a current flowing through the string of solid-state light sources connected to the respective second terminal to a respective maximum value; and
a control circuit configured to generate said reference signal and comprising:
at least one analog-to-digital converter configured to obtain digital samples of the voltages at said second terminal and the voltage between said first and said second output terminals of said voltage source;
a digital-to-analog conversion circuit configured to receive a digital regulation value and provide said reference signal;
a feed-forward control circuit configured to compute a feed-forward regulation value indicative of the requested output voltage by determining a maximum voltage drop between said second terminals and said second output terminal of said voltage source as a function of said digital samples and adding a given head-room to said maximum voltage drop; and
a feed-back control circuit configured to determine a minimum voltage drop at said plurality of current regulators or limiters as a function of said digital samples and determine a feed-back correction value as a function of the difference between said minimum voltage drop and said head-room;

wherein said control circuit is configured, in response to a start-up of said current supply system, to set said digital regulation value to a first value indicative of a maximum requested output voltage, and then repeat the following operations:
determine whether said digital regulation value corresponds to said first value;
set said digital regulation value to said feed-forward regulation value if said digital regulation value is greater than or equal to said first value; and
add said feed-back correction value to said digital regulation value if said digital regulation value is less than said first value.

2. The current supply system according to claim 1 , wherein each of said current regulators or limiters is configured to receive from said control circuit at least one control signal indicating at least a first operating mode and a second operating mode;
wherein the respective current regulator or limiter is configured to deactivate said current if said at least one control signal indicates said first operating mode; and
wherein the respective current regulator or limiter is configured to limit said current to said respective maximum value if said at least one control signal indicates said second operating mode.

3. The current supply system according to claim 2 , wherein said at least one control signal comprises a Pulse-Width Modulated signal, wherein a first logic level of said Pulse-Width Modulated signal indicates said first operating mode and wherein a second logic level of said Pulse-Width Modulated signal indicates said second operating mode.

4. The current supply system according to claim 2 , wherein said at least one control signal indicates said maximum value.

5. The current supply system according to claim 2 , wherein said control circuit is configured to:
determine whether said at least one control signal indicates that said current regulators or limiters should use said first operating mode; and
set said digital regulation value to a second value indicative of a minimum requested output voltage if said at least one control signal indicates that said current regulators or limiters should use said first operating mode.

6. The current supply system according to claim 5 , wherein said control circuit is configured to:
determine whether said digital regulation value corresponds to said second value if said at least one control signal indicates that at least one of said currents regulators or limiters should use said second operating mode; and
set said digital regulation value to said first value if said digital regulation value corresponds to said second value.

7. The current supply system according to claim 2 , wherein said control circuit is configured to:
determine whether said at least one control signal indicates that at least one current regulator or limiter should use said second operating mode;
determine whether a current is flowing through said at least one current regulator or limiter which should use said second operating mode if said at least one control signal indicates that at least one current regulator or limiter should use said second operating mode; and
vary said digital regulation value in order to increase said requested output voltage if no current is flowing through at least one of said current regulators or limiters which should use said second operating mode.

8. The current supply system according to claim 1 , wherein said reference signal is proportional to said requested output voltage to be generated by said voltage source, and wherein said digital-to-analog converter conversion circuit comprises an analog-to-digital converter configured to generate said reference signal as a function of said digital regulation value.

9. The current supply system according to claim 1 , wherein said third terminal is configured to be coupled to a feedback terminal of said voltage source in order to vary a feedback signal indicative of the output voltage generated by said voltage source.

10. An integrated circuit comprising the current supply system according to claim 1 .

11. A power supply system, comprising:
a voltage source configured to generate an output voltage between a first and a second output terminal of said voltage source, wherein said voltage source is configured to generate said output voltage as a function of a reference signal; and
a current supply system according to claim 1 .

12. The power supply system according to claim 11 , comprising:
a plurality of strings of solid-state light sources, wherein each string of solid-state light sources is connected between a respective second terminal and said second output terminal of said voltage source.

Assignees

• St Microelectronics Srl
• Stmicroelectronics Application Gmbh
• St Microelectronics Des & Appl

Inventors

• Tagliavia Donato
• Polisi Vincenzo
• Trecarichi Calogero Andrea
• Mammoliti Francesco Nino
• Barthel Jochen
• Beran Ludek

Classifications

• H05B45/14

  using electrical feedback from LEDs or from LED modules · CPC title

• H05B45/375

  using buck topology · CPC title

• Y02B20/30

  Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED] · CPC title

• H05B45/38

  using boost topology · CPC title

• H05B45/347 Primary

  Dynamic headroom control [DHC] · CPC title