Power Supply Circuit Current Monitoring via Digital Control

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Solution Overview

Problem

Existing power supply circuits for lighting systems, such as those using LEDs or OLEDs, face challenges in effectively monitoring and controlling the current supply to individual lighting modules, which is crucial for maintaining expected light intensity and detecting malfunctions like short-circuits or open-loads.

Innovation Solution

A power supply circuit with multiple output terminals, each equipped with a current supply circuit that adjusts current based on digital control signals, incorporates a current digital-to-analog converter, scaling circuits, and a current sensor to monitor and compare currents against set thresholds, ensuring accurate current provision and detection of deviations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If current monitoring is implemented for each output terminal, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improvecurrent monitoring capabilityVSAvoidcircuit structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a universal current monitoring architecture where a single monitoring circuit structure is reused across multiple output terminals. Each current supply circuit includes identical components (current sensor, digital-to-analog converter, comparator) that can monitor currents at different output terminals, eliminating the need for separate monitoring circuits for each terminal and reducing overall device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The monitoring function is segmented into modular components: current sensors that measure output currents, digital-to-analog converters that process control signals, and comparators that verify current thresholds. This segmentation allows each component to be independently optimized and reused across multiple channels, improving reliability while managing complexity through modularity.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If precise current control is implemented for each lighting module, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:
Improvecurrent control precisionVSAvoidcontrol circuit
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent employs digital-to-analog converters that translate digital control signals into precise analog current values for each lighting module. By changing the digital parameter values, the system can precisely control the current supplied to each module without requiring complex analog control circuits, thereby improving manufacturing precision while keeping the control circuit relatively simple.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces complex mechanical or analog current control mechanisms with digital control systems. Digital signals are used to control the current supply to each lighting module, allowing for precise control through software or digital logic rather than complex analog circuitry, thus improving precision while reducing overall system complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If current verification against thresholds is implemented, then reliability is improved, but loss of time increases due to monitoring overhead

Engineering Contradiction:
Improvecurrent verification capabilityVSAvoidmonitoring time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent implements periodic current verification where the monitoring circuit checks current thresholds at regular intervals rather than continuously. This periodic monitoring approach maintains system reliability by detecting current anomalies at defined checkpoints while reducing the time overhead compared to continuous monitoring, as the system can operate normally between verification points.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The monitoring circuit is designed to autonomously verify current thresholds and generate alerts or control signals when deviations are detected, without requiring external intervention or complex processing. This self-service capability ensures reliable current verification while minimizing the time overhead, as the system automatically handles monitoring and response tasks.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4525557A1Power supply circuit, related system and method
Publication Date: 2025.03.19 STMICROELECTRONICS INT NV
  • EP4525557A1 patent drawingFigure 1
  • EP4525557A1 patent drawingFigure 2
  • EP4525557A1 patent drawingFigure 3~4

AI summary

A power supply circuit (1a) is disclosed. The power supply circuit (1a) comprises a plurality of current supply circuits (121-12k), wherein each current supply circuit (121-12k) is configured to provide an output current (i1-ik) as a function of a respective digital control signal (Curr_Set_CH1-Curr_Set_CHk), and a measurement current (iMON) being proportional to the respective output current (i1-ik). A control circuit (182) selects (184, 186) one of the measurement currents (iMONi) and one of the digital control signals (Curr_Set_CHi) associated with a given current supply circuit (121-12k). A comparison circuit (180) generates a threshold current (iTH) as a function of a threshold control signal (TH) and generates a comparison signal (COMP) by comparing the selected measurement current (iMONi) with the threshold current (iTH). Specifically, the control circuit (182) sets, during a first phase (PH1), the threshold current (iTH) to a first value (iTH1) being smaller than an expected value (iMONi,exp) for the selected measurement current (iMONi) as indicated by the selected digital control signal (Curr_Set_CHi) and, during a second phase (PH2), to a second value (iTH2) being greater than the expected value (iMONi,exp). Next, the control circuit verifies whether the comparison signal (COMP) is de-asserted during the first phase (PH1) and asserted during the second phase (PH2).