LDO Startup Circuit Using Auxiliary Voltage for Charge Pump Activation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Low drop-out voltage regulators (LDOs) face challenges when their output voltage is too low to drive a charge pump, especially in systems with multiple supply voltages, leading to unstable operation and potential failure in regulating voltage levels.
Innovation Solution
Incorporating a switch circuit, a charge pump circuit, and an auxiliary startup circuit, where the charge pump circuit provides a switch control signal to the switch circuit, and an initiation circuit generates an auxiliary output voltage higher than the LDO output voltage to drive the charge pump, ensuring the LDO can operate correctly even when its output is insufficient to activate the charge pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the LDO output voltage is used to drive the charge pump circuit, then the circuit structure is simple, but the charge pump cannot be activated when the LDO output voltage is too low
Solution Approach 1:
The initiation circuit generates an auxiliary output voltage before the LDO is fully operational. This preliminary high voltage is used to activate the charge pump circuit before the LDO output voltage is sufficient, ensuring reliable charge pump activation during the startup phase when the LDO output voltage is still low.
2Reliability
If an auxiliary initiation circuit is added to generate higher voltage, then the charge pump can be activated reliably, but the device complexity increases
Solution Approach 1:
The initiation circuit is designed to operate only during the startup phase when the LDO output voltage is insufficient. Once the LDO is fully operational and its output voltage is sufficient to drive the charge pump, the initiation circuit automatically stops providing auxiliary voltage. This temporary, phase-specific operation minimizes the impact on overall device complexity while ensuring reliable charge pump activation during the critical startup period.
3Adaptability or versatility
If the LDO operates with multiple supply voltages, then the system flexibility is improved, but the output voltage may drop too low to drive the charge pump
Solution Approach 1:
When multiple supply voltages are used, the initiation circuit provides preliminary high voltage to the charge pump during startup before the LDO output stabilizes. This ensures that the charge pump can be activated reliably even when the LDO is operating with multiple supply voltages that may cause the output voltage to be initially too low to drive the charge pump.
Solution Approach 2:
The initiation circuit acts as an intermediary between the multiple supply voltages and the charge pump circuit. It provides the necessary voltage boosting during startup to bridge the gap between the low initial LDO output voltage and the higher voltage required by the charge pump, enabling reliable operation across multiple supply voltage configurations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows the LDO to maintain stable operation across a wide range of input voltages, ensuring the charge pump is properly activated and the system receives the required voltage, even when the LDO output is near the threshold, thereby preventing voltage drops and maintaining system stability.
Implementation Method 1
A charge pump circuit has an input terminal coupled to the output terminal of the LDO unit and an output terminal coupled to a control terminal of the switch circuit. The charge pump circuit receives the output voltage and provides a switch control signal to the switch circuit.
Data Source
AI summary
A low drop-out voltage regulator (LDO) includes an LDO unit, a switch circuit, a charge pump, and an initiation circuit. The switch circuit is coupled to a voltage input terminal and outputs a selected input voltage. The LDO unit receives the selected input voltage from the switch circuit and generates a regulated output voltage. The charge pump is coupled to the LDO unit to receive the regulated output voltage, and generate a control signal that is provided to the switch circuit. The initiation circuit receives the input voltage and generates an initiation voltage that greater than the regulated output voltage. The initiation voltage is provided to the charge pump circuit, along with the regulated output voltage. The initiation voltage drives the charge pump circuit when the regulated output voltage is not large enough to drive the charge pump circuit.