Low Drop-Out Regulator Circuit for Constant Current and Voltage Limit
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Solution Overview
Problem
Conventional low drop-out (LDO) regulators for charging rechargeable batteries are complex and lack simplicity and cost-effectiveness in providing a constant current with a maximum voltage limit.
Innovation Solution
A simplified low drop-out regulator circuit comprising a pass circuit and an amplifying circuit, using P-transistors or PMOSFETs, that controls output voltage and current through feedback mechanisms and reference signals to maintain constant current and voltage limits, with a soft-start function for gradual voltage increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LDO regulator design is used, then voltage and current regulation functions are achieved, but circuit complexity increases
Solution Approach 1:
The patent combines multiple regulation functions (voltage regulation, current regulation, and soft-start) into a single LDO regulator circuit. The pass circuit integrates the pass transistor with the amplifying circuit, and the control circuit handles both voltage and current regulation through unified feedback mechanisms, eliminating the need for separate regulation circuits.
Solution Approach 2:
The LDO regulator is designed to provide multiple functions simultaneously: voltage regulation through the amplifying circuit, constant current limiting through the control circuit monitoring output current, and soft-start functionality through the capacitor-based ramp circuit. This multi-functional design reduces overall system complexity.
2Reliability
If conventional LDO regulator design is used, then regulation functions are provided, but manufacturing cost increases
Solution Approach 1:
The patent merges multiple regulation functions into a single integrated circuit design, reducing the number of discrete components required. The pass circuit, amplifying circuit, and control circuit are designed to work together in one unified structure, lowering manufacturing complexity and cost.
Solution Approach 2:
The control circuit automatically monitors output current and voltage levels, adjusting the pass circuit operation without external intervention. The soft-start function automatically ramps up the output voltage through the capacitor charging mechanism, eliminating the need for external control circuits or complex startup sequences.
3Ease of manufacture
If simplified circuit design is used, then manufacturing cost decreases, but ability to provide constant current and voltage limit decreases
Solution Approach 1:
The amplifying circuit uses feedback from the output voltage to regulate the pass circuit operation, maintaining a stable output voltage. The control circuit monitors the output current and adjusts the pass circuit to maintain constant current operation, ensuring both regulation functions are preserved in the simplified design.
Solution Approach 2:
The control circuit acts as an intermediary between the amplifying circuit and the pass circuit, coordinating their operations to achieve both voltage and current regulation. The feedback signals from output monitoring points serve as intermediaries to convey information about output conditions to the control elements.
Data Source
AI summary
A low drop-out regulator is disclosed. An unregulated DC input terminal receives an input voltage. A pass circuit is coupled between the unregulated DC input terminal and a regulated DC output terminal for supplying a power to the regulated DC output terminal. An amplifying circuit controls the pass circuit for providing a constant voltage or/and a constant current in response to an output voltage or/and an output current.