Multi-Channel DAC Current Limiting for Transient Over-Current Loads
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Solution Overview
Problem
Existing multi-channel digital-to-analog converters (DACs) face inefficiencies due to power supply designs that must meet peak current demands of all channels, leading to costly systems where individual channels are rendered inoperative if their output current exceeds peak limits, even if the total power supply can handle the aggregate demand.
Innovation Solution
A multi-channel DAC system with current control circuits that dynamically adjust output current limits based on start and end limit signals, using current sensors and filters to manage over-current conditions, allowing channels to temporarily exceed peak limits if the total number of channels in over-current state is within a defined maximum, and implementing hysteresis to prevent unnecessary activation and de-activation of over-current protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply is designed to meet the aggregate peak current demand of all DAC channels, then the system can handle maximum current loads, but the system becomes inefficient and expensive
Solution Approach 1:
The patent implements dynamic current limiting where the DAC channels can temporarily exceed their peak current limits when the number of channels in over-current state remains below a maximum threshold. This dynamic adjustment allows the system to adapt to transient load conditions without requiring a power supply sized for absolute peak aggregate demand, thereby improving efficiency while maintaining reliability.
2Reliability
If individual DAC channels are limited to peak current limits, then channel protection is achieved, but channels are rendered inoperative during transient over-current conditions even when total power supply capacity is sufficient
Solution Approach 1:
The patent merges individual channel current limits with a system-level aggregate management mechanism. Instead of independently limiting each channel to its peak current, the system allows multiple channels to collectively exceed individual limits as long as the total number of channels in over-current state does not exceed a maximum threshold. This combines per-channel protection with system-wide resource allocation, improving channel availability during transient conditions while maintaining overall protection.
Solution Approach 2:
The system implements feedback through a controller that monitors the number of DAC channels in over-current state and dynamically adjusts the current limits accordingly. When the number of channels exceeding peak current remains below the maximum threshold, channels are allowed to operate above individual limits. This feedback mechanism ensures channels remain operational during transient conditions while preventing sustained over-current damage.
3Productivity
If dynamic current limiting is implemented to allow temporary over-current operation, then channel availability improves, but system complexity increases due to additional control circuits and monitoring
Solution Approach 1:
The patent segments the current limiting function into modular components: individual current sensors for each DAC channel, per-channel current control circuits, a summer circuit that aggregates over-current status, and a central controller. This segmentation allows the complex dynamic current limiting functionality to be implemented through simple, standardized building blocks, making the system more manageable and maintainable despite the increased functionality.
Data Source
AI summary
A system includes a plurality of digital-to-analog converter (DAC) channels. Each DAC channel includes a current control circuit which receives a start limit signal or an end limit signal. The current control circuit reduces an output current limit of the channel responsive to the start limit signal and increases the output current limit responsive to the end limit signal. Each channel includes a current sensor circuit adapted to measure the output current of the channel and provide a channel over-current alert signal if the output current rises above a high current limit. The system includes a controller which asserts the start limit signal if the number of channels exceeding the high current limit is greater than a maximum allowable number and asserts the end limit signal if the number of channels exceeding the high current limit is less than the maximum allowable number minus a hysteresis value.