Parallel Transistor Series Regulator for Wide Load Stability
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Solution Overview
Problem
Conventional series regulators face challenges in achieving stable operation across a wide load range and fast load response while maintaining low current consumption.
Innovation Solution
A series regulator design that includes a first amplifier driving a high-current transistor and a second amplifier driving a lower-current transistor in parallel, with an amplifier control circuit managing their operation to ensure zero or fixed output current from the lower-current transistor in light-load regions and the high-current transistor in heavy-load regions, allowing for efficient switching and stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single operational amplifier and a single output transistor are used to cover the entire load range, then the device complexity is reduced, but it becomes difficult to achieve stable operation in a wide load range and fast load response combined with low current consumption
Solution Approach 1:
The load range is segmented into light-load region and heavy-load region, with each region handled by a dedicated amplifier-transistor pair. The first amplifier drives the first transistor for heavy loads, while the second amplifier drives the second transistor for light loads. This segmentation allows each component to be optimized for its specific operating region, achieving stable operation across the entire wide load range.
Solution Approach 2:
The system dynamically switches between the first amplifier-transistor pair and the second amplifier-transistor pair based on the load conditions. The amplifier control circuit monitors the output current and activates the appropriate amplifier pair, enabling the system to adapt its configuration to match the operational requirements of each load region.
2Use of energy by moving object
If a single operational amplifier and a single output transistor are used, then the current consumption might be lower, but fast load response cannot be achieved across the entire load range
Solution Approach 1:
Each amplifier-transistor pair is designed with local quality optimized for its specific load region. The first amplifier and first transistor are configured for fast response in heavy-load conditions, while the second amplifier and second transistor are configured for efficient operation in light-load conditions. This local optimization ensures fast load response across the entire load range without excessive current consumption in each region.
3Use of energy by stationary object
If the second transistor has lower current capability than the first transistor, then the second amplifier can consume lower current, but the system must implement complex control logic to manage the switching between amplifiers
Solution Approach 1:
The amplifier control circuit automatically monitors the output current and self-regulates which amplifier pair is active based on predefined threshold conditions. When the output current exceeds the switching threshold, the control circuit activates the first amplifier pair; when it remains below the threshold, the second amplifier pair remains active. This self-service approach manages the complexity of switching control without requiring external intervention.
Data Source
AI summary
A series regulator includes, for example, first and second operational amplifiers, for driving a first transistor for a heavy load and a second transistor for a light load respectively, and an amplifier control circuit. The amplifier control circuit controls the first and second operational amplifiers such that, in a light load region, a first output current passing through the first transistor has a zero value and a second output current passing through the second transistor covers the entire output current passing through a load, and such that, in a heavy load region, the second output current has a zero value (or a fixed value lower than an amplifier switching threshold value) and the first output current covers the entire output current (or a difference left by subtracting the second output current from the output current).