Dual-Mode Supply Circuit for Low-Voltage Power-Up Stability
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Solution Overview
Problem
Integrated circuits (ICs) face challenges in operating reliably across dual power modes, particularly in low voltage mode, where existing approaches often result in increased standby leakage current and unreliable power-up sequences due to the generation of reference and feedback voltages.
Innovation Solution
A dual mode supply circuit is designed with enabling circuits coupled to amplifier input terminals, disabling reference and feedback voltage generation in low voltage mode to improve power-up reliability and reduce standby leakage current, featuring a configuration with branches including passive and switching devices to manage voltage levels effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reference and feedback voltages are generated in low voltage mode, then the amplifier can control the output node, but standby leakage current increases
Solution Approach 1:
The enabling circuits are configured to disable reference and feedback voltage generation before the power-up sequence begins in low voltage mode. This preliminary action prevents the amplifier from attempting to control the output node before proper voltage levels are established, thereby improving power-up reliability while avoiding unnecessary leakage current
Solution Approach 2:
The patent extracts and removes the reference and feedback voltage generation functions during low voltage mode operation by using enabling circuits to disconnect these voltage generation paths. This separation allows the system to operate in low voltage mode without the harmful side effect of generating reference and feedback voltages that would increase standby leakage current
2Loss of energy
If reference and feedback voltages are generated, then amplifier control is enabled, but power-up sequence reliability decreases in low voltage mode
Solution Approach 1:
The enabling circuits perform a preliminary check of the voltage mode and accordingly enable or disable reference and feedback voltage generation before the power-up sequence initiates. In low voltage mode, this preliminary action disables voltage generation, preventing reliability issues while maintaining low standby leakage current
Solution Approach 2:
The enabling circuits act as intermediaries between the voltage mode detection logic and the reference/feedback voltage generation circuits. They mediate by conditionally enabling or disabling voltage generation based on the operating mode, thereby resolving the conflict between amplifier control requirements and power-up reliability
Data Source
AI summary
A circuit includes a power supply node, a reference node, an output node, a first transistor coupled between the power supply and output nodes, and an amplifier including a non-inverting input coupled to the power supply node through a first passive device, an inverting input coupled to the reference node through a second passive device, and an output coupled to a gate of the first transistor. A first inverter is coupled between the output and reference nodes and generates a mode control signal responsive to a mode select signal, a first switching device is configured to, responsive to the mode control signal, selectively couple the non-inverting input of the amplifier to the reference node through a third passive device, and a second switching device is configured to, responsive to the mode control signal, selectively couple the inverting input of the amplifier to the output node through a fourth passive device.