LED Driver Channel Short Detection Using Integrated Force-Sense Circuits

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Solution Overview

Problem

Existing LED lighting systems require external test equipment or visual inspection to detect shorts between output pins and ground, adding time and complexity to the fabrication process.

Innovation Solution

Incorporating fault detection circuits within the LED driver chip to detect shorts between adjacent output pins and between output pins and ground, using current sourcing and sensing circuits with comparators to determine voltage differences relative to a reference voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If external test equipment is used to detect shorts between output pins and ground, then fault detection capability is provided, but fabrication time increases and manufacturing complexity increases

Engineering Contradiction:

Improvefault detection capabilityVSAvoidfabrication time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The fault detection circuit is merged with the LED driver chip, combining the driving function and fault detection function into a single integrated device. The current sourcing circuit, current sensing circuit, and comparator are all integrated within the driver chip, eliminating the need for external test equipment and reducing fabrication time.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The LED driver chip performs self-diagnosis by incorporating fault detection circuitry that automatically detects shorts between output pins and ground without requiring external intervention. The chip monitors its own output pins using internal current sourcing and sensing circuits, enabling autonomous fault detection during operation.

Inventive Principle:

Principle #25Self-service

2Reliability

If external test equipment is used to detect shorts between output pins, then fault detection capability is provided, but manufacturing complexity increases

Engineering Contradiction:

Improvefault detection capabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated fault detection circuit serves multiple functions: it detects shorts between output pins and ground, monitors LED string integrity, and provides operational status information. This multi-functional approach reduces the need for separate testing equipment and simplifies the manufacturing process.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If fault detection circuits are integrated within the LED driver chip, then fabrication time is reduced and manufacturing complexity is reduced, but device complexity increases

Engineering Contradiction:

Improvefabrication speedVSAvoidchip circuit complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The fault detection circuit is segmented into distinct functional modules: a current sourcing circuit that provides test current, a current sensing circuit that measures the current, and a comparator that evaluates the sensed current against a reference. This modular segmentation manages internal complexity while enabling integrated implementation within the driver chip.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The circuit utilizes changes in electrical parameters (current magnitude, voltage levels) to detect faults. By monitoring parameter variations through the current sensing circuit and comparator, the system achieves fault detection capability through parameter-based measurement rather than complex structural arrangements.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables in-chip fault detection without external equipment, reducing fabrication time and preventing potential damage to the LED lighting system by identifying and preventing shorts during operation.

Implementation Method 1

a current sensor coupled to the force output node, and a comparator configured to compare a voltage at the force output node to a reference voltage

Methodology Applied

Scientific EffectOhm's Law: Ohm's Law

Implementation Method 2

a comparator configured to compare a voltage at the force output node to a reference voltage and generate a comparison output based thereupon

Methodology Applied

Scientific EffectVoltage comparison:

Data Source

PatentEP4284120B1LED array driver with channel to channel and channel to ground external pin short detection

Publication Date: 2026.03.25 STMICROELECTRONICS SRL

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AI summary

A LED driver chip includes driver circuits, each being coupled to a different pin and including a fault-detection circuit. Each fault-detection circuit includes a force circuit forcing current to a force node, and a sense circuit including a current sensor coupled to the force node, and a comparator comparing a voltage at the force node to a reference voltage to generate a comparison output. Control circuitry, in a pin-to-pin short detection mode, activates the force circuit of a first of the driver circuits and activates the sense circuit of a second of the driver circuits, in a pin-to-ground short detection mode, activates the force and the sense circuit of the same driver circuits. The comparison output of the comparator of the activated sense circuit, if is higher or if lower of the reference voltage, indicates if short between pin or to ground, respectively, is present.