High-Voltage Regulator Disable Circuit for Asynchronous Supply Sequences
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Solution Overview
Problem
Existing voltage regulators face challenges in being disabled independently of supply voltage sequences and are prone to undesirable electrical flow conditions when powered by asynchronous external sources, potentially damaging components due to voltage mismatches.
Innovation Solution
A circuit comprising a voltage selection circuit and a power-down generator circuit that generates a selected voltage based on the higher of two supply voltages, adjusting the power-down signal to prevent voltage drops exceeding component ratings, ensuring safe disablement of voltage regulators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage regulator is disabled independently of supply voltage sequence, then the regulator can be safely powered down, but voltage mismatches may cause undesirable electrical flow conditions
Solution Approach 1:
The circuit performs preliminary voltage comparison before disabling the regulator. The first transistor component compares the first voltage source to the second voltage source in advance, and only disables the regulator when the first voltage source is confirmed to be higher, preventing reverse current flow conditions before they can occur.
Solution Approach 2:
The voltage selection circuit acts as an intermediary between the two voltage sources and the regulator. It uses the first transistor component to selectively connect the higher voltage source to the regulator, ensuring that the regulator always receives the higher of the two voltages and preventing harmful reverse current flow.
2Adaptability or versatility
If the voltage regulator is disabled when low voltage supply is provided externally, then the regulator can operate in high voltage mode, but asynchronous power supply changes may lead to voltage mismatches
Solution Approach 1:
The circuit dynamically adapts to different power supply configurations by continuously monitoring the voltages from both the first and second voltage sources. The voltage selection circuit automatically switches between operating modes based on which voltage source is higher, enabling the regulator to support multiple power domains while maintaining reliability through real-time voltage comparison.
3Device complexity
If a simple disable mechanism is used, then the circuit complexity is reduced, but the circuit cannot tolerate high voltages or prevent reverse current flow
Solution Approach 1:
The voltage selection circuit performs self-service by automatically comparing the two voltage sources and selecting the higher one without external intervention. The first transistor component self-regulates the connection between voltage sources based on voltage levels, eliminating the need for complex external control circuitry while maintaining high voltage tolerance and preventing reverse current flow.
Data Source
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AI summary
A power management unit utilizing a circuit to disable a voltage regulator is provided. The circuit includes a voltage selection circuit (528) and a power-down switching device. The voltage selection circuit configured to receive a first voltage source (510) and a second voltage source (512) to output a selected voltage (526) based on the higher of the two input voltages. The voltage selection circuit (528) utilizes a first transistor (550) electrically connected in parallel with a second transistor (551) between the first voltage source (510) and the second voltage source (512) to generate the selected voltage (526). The second transistor gate voltage at the second transistor gate (551b) is generated based at least in part on a voltage at the first transistor drain (550c). The selected voltage (526) is generated based on a voltage at the second transistor drain (551c). The power-down switching device is configured to generate a voltage for a voltage regulator based on the selected voltage.