Trace Capture Buffer Power Gating Debug Circuit
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Solution Overview
Problem
Combining power gating and tracing in electronic circuits poses challenges, particularly when faults occur during power gating sequences, as storage devices are power-gated, making it difficult to capture events leading up to the fault and diagnose or remedy the issue.
Innovation Solution
A method and circuit configuration that maintain operation of a trace capture buffer during power gating sequences by keeping power on the buffer while turning off power to other parts of the circuit, allowing events to be recorded and analyzed for fault diagnosis and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If power gating is applied to storage devices during circuit operation, then power consumption is reduced, but the ability to capture and record events for fault diagnosis is lost
Solution Approach 1:
The circuit is divided into power-gated domains and a non-power-gated debug domain. The TCB and associated debugging circuitry are placed in a separate domain that remains powered during power gating operations, allowing event recording to continue while other parts of the circuit enter low-power mode.
Solution Approach 2:
A dedicated debug domain acts as an intermediary between the power-gated circuit domains and the external debugging system. This intermediate domain maintains power supply and clock signals specifically for the TCB, enabling continuous event capture without requiring the entire circuit to remain powered.
2Loss of energy
If power is turned off to storage devices during idle periods, then power consumption is conserved, but fault diagnosis capability is impaired when faults occur during power gating sequences
Solution Approach 1:
The TCB continuously captures and stores event information before faults occur, even during power gating sequences. This preliminary recording of events ensures that diagnostic data is already available when a fault is detected, eliminating the need to maintain power to storage devices solely for diagnostic purposes.
Solution Approach 2:
The TCB creates a copy of event data in a non-volatile or maintained-power buffer that can be read later for analysis. This copying mechanism preserves diagnostic information without requiring the original storage devices to remain powered, allowing power conservation while maintaining fault diagnosis capability.
3Loss of energy
If the trace capture buffer is power-gated along with other circuit components, then overall power consumption is reduced, but the ability to trace and analyze faults during power gating operations is eliminated
Solution Approach 1:
The power domain architecture is segmented to separate the TCB from other circuit components. The TCB resides in a dedicated debug domain that is excluded from power gating control signals, allowing it to remain powered while other domains are power-gated, thus maintaining tracing capability without sacrificing overall power savings.
Solution Approach 2:
The debug domain serves multiple functions: it houses the TCB for event recording, provides a stable reference for debugging operations, and enables both normal circuit operation and fault diagnosis capabilities. This multi-functional domain design allows the system to achieve both power conservation and maintained tracing capability.
Data Source
AI summary
Described are a circuit and a method of analyzing and correcting a fault occurring in operation of the circuit during a power gating sequence. The method includes executing a modification of the power gating sequence that includes maintaining operation of a trace capture buffer (TCB); recording, in the TCB, events occurring during the executing; and correcting the fault based on analysis of the events recorded in the TCB. The circuit includes a plurality of components including a TCB, and a switch configured to maintain power to the TCB in a first state and turn off power to the TCB in a second state.