Over-Drive LDO Power-Down Control for Safe Low-Current Operation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Over-drive LDO regulators face challenges in maintaining a safe operating area (SOA) during power down operations, leading to issues such as falling below voltage thresholds or experiencing unintended frequency responses, particularly when transitioning to low power modes.
Innovation Solution
Designing an LDO regulator circuit that operates at low current and includes a current boost mechanism responsive to power down signals, utilizing protection circuitry and operational amplifiers to maintain a stable output voltage without requiring additional high ground (HG) voltage, thereby ensuring operation within the SOA range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an LDO regulator operates at low current during power down mode, then power consumption is reduced, but the regulator may fall below voltage thresholds and exit safe operating area (SOA)
Solution Approach 1:
The LDO regulator dynamically adjusts its operating current based on the operational mode. During normal operation, it operates at higher current to ensure stable regulation, while during power down mode, it transitions to low current operation. The patent implements dynamic control through mode detection circuitry that monitors operational conditions and adjusts bias currents accordingly, allowing the regulator to adapt between these two states without compromising SOA in either mode.
Solution Approach 2:
The patent changes key operating parameters (current levels, voltage thresholds) based on the operational mode. During power down, the regulator modifies its internal reference voltages and bias currents to accommodate low-power operation while maintaining adequate headroom above minimum thresholds. This parameter adjustment allows the system to operate reliably at lower currents without falling below critical voltage thresholds that would exit the safe operating area.
2Reliability
If protection circuitry is added to maintain SOA during power down, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines the protection functionality with the existing LDO regulator structure by integrating mode detection and dynamic biasing into the core regulation circuitry. Rather than adding separate protection circuits, the design merges the power down detection and SOA maintenance functions into the existing error amplifier and bias generation stages. This integration approach maintains reliability while minimizing the increase in device complexity.
Solution Approach 2:
The LDO regulator employs self-service mechanisms where the circuit automatically detects power down conditions and adjusts its own operating parameters without external intervention. The mode detection circuitry monitors voltage levels and automatically transitions the regulator to appropriate operating modes, eliminating the need for complex external control logic or additional protection components. This self-adjusting capability maintains SOA while keeping the overall system simple.
3Reliability
If additional LDO regulators are used to provide middle-level voltage during power down, then voltage threshold maintenance is improved, but area and power costs increase
Solution Approach 1:
The patent makes the single LDO regulator multi-functional by enabling it to operate in both normal regulation mode and power down mode with different current levels. The regulator maintains voltage threshold compliance in both modes through dynamic parameter adjustment, eliminating the need for separate dedicated circuits for different voltage levels. This universal approach allows one regulator to perform the work that would otherwise require multiple specialized regulators, reducing area and power overhead.
4Reliability
If current boost is provided during power down mode, then safe operating area is maintained, but current consumption increases
Solution Approach 1:
The patent implements periodic or conditional current boosting rather than continuous boosting. The circuit monitors power down mode indicators and applies current boost only when specifically needed to maintain SOA, rather than continuously during the entire power down period. This conditional activation allows the system to achieve reliable SOA maintenance during critical transitions while minimizing unnecessary current consumption during stable power down operation.
Data Source
AI summary
Systems and methods are provided for controlling power down of an overdrive low drop out regulator circuits. The system is designed with a low dropout regulator circuit configured to operate in a safe operating area range of operation with very low current. The circuit contains a regulator, a current boost, and a power down switch. The current boost is responsive to a power down signal, generally from a power distribution board. The circuit is fabricated such that the low dropout regulator circuit with the current boost operates with minimum current pull while maintaining safe operating area range of operation. The safe operating area range of operation is maintained during various design operations, normal operations, and power down. This regulator circuit may be designed without a middle level voltage or high-ground.