Linear Regulator Driver Circuit Biasing for Low Quiescent Current
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Solution Overview
Problem
Existing linear regulator circuits face high current consumption, particularly due to the need for a strong driver circuit to maintain loading capability and efficiency, leading to significant power loss and inefficiency, especially when load requirements are low.
Innovation Solution
A linear regulator control circuit design that includes a feedback network, an error amplifier, and a driver circuit where the second power supply terminal of the driver circuit is directly connected to the output voltage node, reducing the quiescent current by integrating the bias current of the driver circuit into the load current, thus minimizing standby current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a strong driver circuit is used to maintain loading capability, then the loading capability is improved, but the current consumption increases
Solution Approach 1:
The driver circuit's second power supply terminal is connected to the output voltage node instead of a fixed ground reference, making the driver circuit's reference potential dynamic and dependent on the output voltage. This allows the driver circuit to operate with lower voltage headroom while maintaining its ability to drive the power transistor effectively, thus reducing quiescent current consumption without sacrificing loading capability.
2Use of energy by moving object
If the driver circuit is optimized for low current consumption, then the current consumption is reduced, but the loading capability deteriorates
Solution Approach 1:
The output voltage node serves as an intermediary reference point for the driver circuit's second power supply terminal. This intermediary connection allows the driver circuit to leverage the output voltage itself as a reference, enabling it to maintain proper drive signals for the power transistor while consuming less current, as it no longer requires a full voltage swing relative to ground.
3Use of energy by moving object
If the quiescent current is reduced by connecting the driver circuit's second power supply terminal to the output voltage node, then the quiescent current is reduced, but the power supply reference stability may deteriorate
Solution Approach 1:
The connection of the driver circuit's second power supply terminal to the output voltage node creates a natural feedback mechanism where the driver circuit automatically adjusts its operation based on the output voltage level. This feedback ensures that the driver maintains appropriate drive signals while adapting to output voltage variations, thereby maintaining system stability without requiring additional current for reference stabilization.
Data Source
AI summary
A linear regulator circuit includes a power transistor coupled between an input voltage node and an output voltage node. A control circuit of the linear regulator includes a feedback network having an input coupled to the output voltage node and an output configured to generate a feedback voltage. An error amplifier receives a reference voltage and the feedback voltage to generate an error signal. A driver circuit receives the error signal and has an output coupled to drive a control terminal of the power transistor. A first power supply terminal of the driver circuit is coupled to a first power supply node and a second power supply terminal of the driver circuit is coupled to the output voltage node. The bias current for operation of the driver circuit is accordingly directly sourced to the output voltage node to support low quiescent current operation of the regulator circuit.