Charge Pump Control for Low-Dropout Regulator Efficiency
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Solution Overview
Problem
Low-dropout regulators (LDOs) face inefficiencies due to high dropout voltages, leading to increased power dissipation and heat, as they require an upper voltage that is often higher than the input voltage, which can be costly and inefficient, especially when the input voltage is low.
Innovation Solution
A voltage regulator system that includes a charge pump and charge pump control circuit to generate a higher charge pump voltage based on the input voltage, while ensuring it does not exceed a maximum voltage, and an under-voltage lockout circuit to enable the LDO only when the charge pump voltage meets specific conditions, ensuring efficient operation and reducing power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charge pump voltage is increased to ensure LDO operation, then the LDO can operate reliably, but the power dissipation and heat increase
Solution Approach 1:
The charge pump voltage is dynamically adjusted based on the input voltage level. When the input voltage is low, the charge pump generates a higher voltage to ensure the LDO transistor has sufficient voltage headroom for operation. When the input voltage is high, the charge pump voltage is reduced to minimize power dissipation. This dynamic adjustment resolves the contradiction between ensuring reliable operation and minimizing energy loss.
Solution Approach 2:
The system changes the charge pump voltage parameter adaptively based on operating conditions. The charge pump control circuit monitors the input voltage and adjusts the charge pump output voltage accordingly, changing from a fixed high voltage to a variable voltage that optimizes both reliability and energy efficiency across different operating points.
2Reliability
If the charge pump voltage is set higher than the input voltage to ensure transistor operation, then the LDO can regulate properly, but the dropout voltage increases
Solution Approach 1:
The charge pump voltage is dynamically adjusted to be just sufficiently higher than the input voltage when needed, rather than always being set to a fixed high value. This dynamic adjustment ensures the transistor has the minimum necessary voltage headroom for proper operation while minimizing the excess voltage that would increase dropout voltage and power loss.
3Reliability
If a fixed high charge pump voltage is used to ensure LDO operation across all input voltages, then the LDO operates reliably, but the system becomes inefficient when the input voltage is already high
Solution Approach 1:
The charge pump control circuit dynamically adjusts the charge pump voltage based on the input voltage level. When the input voltage is low, the charge pump operates at high voltage to ensure LDO reliability. When the input voltage is already high, the charge pump voltage is reduced or disabled, improving system efficiency. This dynamic behavior maintains reliability across the full voltage range while optimizing efficiency at different operating points.
Solution Approach 2:
The system changes the charge pump voltage parameter adaptively based on operating conditions. The charge pump control circuit monitors the input voltage and adjusts the charge pump output voltage accordingly, changing from a fixed high voltage to a variable voltage that optimizes both reliability and energy efficiency across different operating points.
Data Source
AI summary
A system and method for controlling a low-dropout regulator (LDO) is disclosed. The system and method include a charge pump that is controlled to provide a charge pump voltage to power the LDO. The charge pump voltage can be adjusted relative to the LDO's input voltage to ensure efficient operation of the LDO for input voltages over a range. The charge pump is also controlled to limit the maximum charge pump voltage provided to ensure safe operation of the LDO. The system and method also include a under voltage lockout circuit that enables the LDO when it is determined that the charge pump voltage is sufficient to meet multiple criteria. For example, the charge pump voltage may be analyzed to determine if it is above a minimum voltage and if it is also sufficiently higher than the LDO's output voltage.