Timer-Controlled Driver Circuit for Short and Open Fault Detection
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Solution Overview
Problem
Conventional driver circuits fail to accurately differentiate between short circuit and normal slewing conditions, leading to false short circuit determinations and increased settling time, and also generate false open circuit flags due to dynamic voltage changes, resulting in inappropriate current limiting and prolonged discharge times.
Innovation Solution
A driver circuit with a programmable timer and timer logic that adjusts the slew rate delay period and increases the current limit during slewing events, allowing for differentiation between short circuits and normal slewing conditions, and delays open circuit error flags for short duration events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current limiting is applied during slewing to prevent false shorts, then false error flags are reduced, but settling time increases
Solution Approach 1:
The current limiting threshold is made dynamic through the timer control mechanism. During the predetermined time period after power-on or reset, the current limit is raised to allow aggressive slewing and fast settling. After this time period expires, the current limit returns to normal levels for accurate short circuit protection. This dynamic adjustment of limiting strength based on temporal context resolves the contradiction between fast settling and accurate fault detection.
Data Source
AI summary
A driver circuit uses a feedback loop having a programmable timer and timer logic to adjust a slew rate delay period used to accommodate slewing current when charging or discharging a load capacitor, and to increase the current limit during the slew rate delay period by selecting a larger input current reference value. Increasing the current limit provides for a faster settling time. The value of each input current reference value can be programmed. The programmable timer and the timer logic can be configured to coordinate the slew rate delay period and the selected input current reference value. The slew rate delay period can be adjusted based on which input current reference value is applied.