LED Circuit Current Monitoring with Shared Sensing Pins
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Solution Overview
Problem
Existing LED driver circuits face challenges in accurately monitoring current through multiple LED strings with different current levels, often requiring excessive sensing pins that increase complexity and cost, while achieving precise current sensing is difficult due to varying current levels across strings.
Innovation Solution
The proposed LED circuit employs two current sensing resistors positioned between specific nodes, allowing current to flow through one string while approximately zero current flows through the other, using only two sensing pins for accurate monitoring across multiple strings, thereby reducing the need for additional pins and improving precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensing pins are used to monitor current through multiple LED strings, then current monitoring accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple current sensing functions into a single shared sensing pin. By using a tree-structured resistor network where multiple LED string currents converge through series and parallel resistor combinations, the voltage signal at the shared sensing pin represents the sum of currents from multiple LED strings. This allows one pin to perform what would traditionally require multiple separate pins, reducing device complexity while maintaining measurement capability.
Solution Approach 2:
The shared sensing pin serves multiple functions simultaneously - it monitors current through multiple different LED strings that are connected through the resistor network. The single pin becomes a universal sensing point that can detect current information from various LED strings by manipulating the resistor configuration, eliminating the need for dedicated sensing pins for each LED string.
2Measurement precision
If multiple sensing pins are used for current monitoring, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges multiple sensing functions into a single pin, directly reducing the bill of materials cost associated with multiple pins. The resistor network architecture allows multiple LED string currents to be combined and sensed through one shared pin, eliminating the need to manufacture and assemble multiple separate sensing pin connections, thereby reducing manufacturing cost.
3Power
If current flows through one LED string, then power delivery to that string is improved, but current monitoring accuracy for other strings deteriorates
Solution Approach 1:
The patent implements periodic switching between different LED strings, where currents are delivered in alternating intervals rather than simultaneously. During each period, one LED string receives power while others are off, and the resistor network is reconfigured to sense current through the active string. This periodic operation allows accurate monitoring of each string when it is active, while maintaining the capability to switch to other strings in subsequent periods.
Solution Approach 2:
The patent uses dynamic switching of the resistor network configuration to adapt the sensing path according to which LED string is currently active. The resistors are switched between series and parallel connections based on which LED string needs to be monitored, allowing the circuit to dynamically reconfigure its sensing architecture to maintain measurement precision regardless of which string is powered.
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
This configuration enables precise current monitoring of multiple LED strings with reduced pin count, enhancing accuracy and simplifying the circuit design while maintaining effective power control across different LED strings.
Implementation Method 1
a voltage drop between the first electrical contact element and the second electrical contact element is defined by the first current sensing resistor when current flows through the first LED string
Data Source
AI summary
This disclosure is directed to a light emitting diode (LED) circuit for driving two or more different LED strings, which may be controlled in a complimentary fashion. The LED circuit includes current monitoring capabilities that are configured to monitor current through the two or more different LED strings. The circuit is designed in a way that can reduce or eliminate excessive sensing pins that are otherwise needed for the current monitoring. According to this disclosure, for example, very accurate current monitoring can be achieved by using two or more sensing resistors while only using two sensing pins for the current monitoring through two or more different LED strings.