Two-Stage Power Domain Detection Circuit for Crowbar Current Isolation
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Solution Overview
Problem
In circuits with two power domains, when the supply voltage of one domain is low while the other is high, the first stage circuit does not operate, leading to an unknown output terminal that can induce high crowbar currents in the second stage circuit.
Innovation Solution
A power level detection circuit comprising a resistive circuit, a pull-up circuit, and a pull-down circuit, which controls the transition of a detection signal based on the supply voltages of both power domains to manage the operation mode of the second stage circuit, thereby preventing crowbar currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the first stage circuit operates in a first power domain with low supply voltage while the second stage circuit operates in a second power domain with high supply voltage, then the second stage circuit can operate independently, but the output terminal of the first stage circuit induces high crowbar currents in the second stage circuit
Solution Approach 1:
The power level detection circuit detects the supply voltage level of the first power domain before the second stage circuit operates, and generates a detection signal in advance to control the isolation switch. This preliminary detection and control action prevents the crowbar current problem from occurring when the first stage circuit outputs to the second stage circuit under mismatched power conditions.
Solution Approach 2:
The power level detection circuit and isolation switch are introduced as intermediary components between the first and second power domains. The detection circuit monitors the power level and controls the isolation switch to disconnect or connect the stages appropriately, thereby preventing harmful crowbar currents while enabling independent operation when conditions are suitable.
2Loss of energy
If the output terminal of the first stage circuit is left in an unknown state due to low supply voltage, then the first stage circuit conserves energy, but it induces high crowbar currents in the second stage circuit
Solution Approach 1:
The power level detection circuit continuously monitors the supply voltage level of the first power domain and provides feedback through the detection signal to the isolation switch control. This feedback mechanism ensures that the isolation switch state is dynamically adjusted based on the actual power level, preventing crowbar currents while allowing energy-efficient standby when voltage is low.
Solution Approach 2:
Before the second stage circuit can operate, the power level detection circuit preliminarily checks whether the first power domain has sufficient voltage. If the voltage is insufficient, the detection signal keeps the isolation switch open, preventing the harmful interaction and crowbar currents before they can occur.
3Device complexity
If a simple power domain configuration is used without power level detection, then the device complexity is reduced, but crowbar currents cannot be prevented
Solution Approach 1:
A power level detection circuit is introduced as an intermediary component between the first and second power domains. This detection circuit monitors the power level and controls an isolation switch to prevent crowbar currents, adding minimal complexity while effectively solving the harmful current issue.
Solution Approach 2:
The power level detection circuit automatically detects the supply voltage level and generates the appropriate detection signal without external intervention. The isolation switch is self-controlled by the detection signal, enabling the system to automatically prevent crowbar currents based on the actual power conditions.
Data Source
AI summary
A power level detection circuit is provided. The power level detection circuit includes a resistive circuit, a pull-up circuit, a pull-down circuit, and an output terminal. The resistive circuit is coupled between a first power terminal and a first node. The first terminal is coupled to a first supply voltage. The pull-up circuit is coupled between a second power terminal and a second node. The second power terminal is coupled to a second supply voltage. The pull-down circuit is coupled between the second node and a common ground. The output terminal is coupled to the second node and configured to output a detection signal. The pull-up circuit and the pull-down circuit are configured to control a time point that the detection signal starts to transition from a first level to a second level according to the first supply voltage and the second supply voltage.