Digital PWM Controller Programmable Safe State Fault Management
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Solution Overview
Problem
DC-DC power converters face challenges in safely transitioning to a stable state during shutdown, particularly in high current applications, where existing digital controllers lack efficient mechanisms to manage outputs and ensure safe operation.
Innovation Solution
A digital controller apparatus that includes a multiplexer to manage outputs by connecting switching control signals or control register inputs based on interrupts or software signals, ensuring a safe state is maintained during shutdown through controlled logic and interrupt handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a digital controller is used in high current DC-DC power converter applications, then control precision and stability are improved, but the ability to safely transition to a stable state during shutdown is insufficient
Solution Approach 1:
The patent implements preliminary action by providing a dedicated shutdown management mechanism that is activated before the normal shutdown process. The multiplexer is pre-configured with shutdown control logic that automatically switches outputs to a safe state when shutdown conditions are detected, ensuring that the controller is ready to safely transition before the actual shutdown begins. This prevents unsafe states from occurring during the shutdown transition.
2Reliability
If existing digital controllers are used without dedicated shutdown management, then device complexity is reduced, but safety and stability during shutdown cannot be ensured
Solution Approach 1:
The patent applies universality by designing a multiplexer that serves multiple functions: during normal operation, it routes control signals from the digital controller to the power converter; during shutdown, it automatically switches to route safe state signals. This single component handles both operational modes, adding shutdown management capability without requiring entirely separate shutdown circuitry, thus limiting the increase in overall device complexity.
Solution Approach 2:
The multiplexer acts as an intermediary component between the digital controller and the power converter outputs. During shutdown, it mediates the transition by blocking control signals from the digital controller and replacing them with predetermined safe state signals, ensuring that the power converter enters a safe state without requiring direct modification of the digital controller's internal shutdown logic.
3Object-affected harmful factors
If control outputs are not forced to safe state during shutdown, then device complexity is minimized, but harmful effects such as unstable operation in high current applications occur
Solution Approach 1:
The patent implements preliminary anti-action by proactively preventing harmful unstable operation during shutdown through the multiplexer's automatic safe state switching. Rather than allowing the control outputs to drift into unsafe states and then correcting them, the system preemptively switches to safe state signals before instability can occur, counteracting the potential harmful effect before it manifests.
Data Source
AI summary
An apparatus for forcing outputs of a digital controller of a switching power converter to a safe state during shutdown of the switching power converter is described. The apparatus includes a multiplexer providing an output signal of the digital controller and having a first input of the multiplexer connected to receive a switching control signal control signal from the digital controller. The multiplexer also has a plurality of inputs from control registers providing programmed safe state values. The multiplexer connects one of the first input or the inputs from the plurality of control registers to the output of the multiplexer responsive to a multiplexer control signal. Control logic generates the multiplexer control signal responsive to at least one of an end of frame interrupt, an over current interrupt, an enable interrupt or a software bypass signal.