Low Quiescent Current Voltage Regulator with Dynamic Current Limiting
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Solution Overview
Problem
Conventional current limiting circuits in low dropout voltage regulators and DC-DC converters consume high quiescent current, especially under no load conditions, which is undesirable for portable electronic devices aiming to minimize standby power consumption.
Innovation Solution
A current limiting circuit comprising a current sampling circuit, a current mirror circuit, a current to voltage converter, and a voltage comparator is implemented, which samples and mirrors the current passing through the output pass circuit, converts it to voltage, and compares it with a threshold voltage to control the output pass circuit, thereby minimizing quiescent current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional current limiting circuit is used in a voltage regulator, then current protection during short circuit or overload is achieved, but quiescent current consumption becomes excessively high
Solution Approach 1:
The patent implements dynamic control of the current limiting circuit by using a control signal to enable or disable the circuit based on operating conditions. The circuit transitions from a static always-on design to a dynamic design where the current limiting function is activated only when needed, reducing quiescent current consumption during normal operation while maintaining protection capability when required.
Solution Approach 2:
The patent changes the operational parameters of the current limiting circuit by adjusting the reference current level and using variable gain amplifiers to scale the current limiting threshold based on load conditions. This allows the circuit to adapt its current consumption characteristics to match the actual operating requirements, minimizing quiescent current while maintaining adequate protection.
2Reliability
If the current limiting circuit is always active to ensure protection, then reliability is improved, but power consumption increases especially under no load conditions
Solution Approach 1:
The patent implements periodic or conditional activation of the current limiting circuit rather than continuous operation. The circuit is enabled periodically or based on specific conditions (such as detecting abnormal current levels), allowing the system to maintain protection capability while minimizing standby power consumption during normal no-load conditions.
Solution Approach 2:
The patent extracts the essential protection function from the always-on current limiting circuit and implements it as a separate controllable module. This allows the core current limiting capability to be preserved and activated only when needed, while separating it from the always-active power consumption path, thus reducing standby power while maintaining reliability.
3Measurement precision
If high precision current sampling is used to improve current limiting accuracy, then measurement precision is improved, but quiescent current consumption increases
Solution Approach 1:
The patent applies partial precision to the current sampling circuit by using adequate but not excessive sampling resolution. The design uses a sampling ratio that provides sufficient accuracy for current limiting protection without implementing full-precision measurement throughout the entire signal chain, thereby achieving acceptable measurement precision while minimizing the current consumption of the sampling circuit.
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
The solution significantly reduces quiescent current consumption to the nanoampere range, enhancing the accuracy and consistency of current limiting while maintaining the performance of the voltage regulator, and is applicable to various voltage regulators and converters.
Implementation Method 1
a current sampling circuit for sampling the current passing through the output pass circuit to obtain a duplicated current being proportional to the current passing through the output pass circuit
Implementation Method 2
a current mirror circuit for producing a mirror current being proportional to the duplicated current with the duplicated current as a reference current
Implementation Method 3
a current to voltage converter for producing a voltage being proportional to the mirror current
Implementation Method 4
a voltage comparator for comparing the voltage produced by the current to voltage converter with a threshold voltage and turning off the output pass circuit when the voltage produced by the current to voltage converter is larger than or equal to the threshold voltage
Data Source
AI summary
Techniques pertaining to a voltage regulator with a current limiting circuit having low quiescent current are disclosed. According to one aspect of the present invention, a current limiting circuit is provided for limiting a current passing through an output pass circuit of a voltage regulator, the current limiting circuit comprises: a current sampling circuit for sampling the current passing through the output pass circuit to obtain a duplicated current being proportional to the current passing through the output pass circuit; a current mirror circuit for producing a mirror current being proportional to the duplicated current with the duplicated current as a reference current; a current to voltage converter for producing a voltage being proportional to the mirror current; and a voltage comparator for comparing the voltage produced by the current to voltage converter with a threshold voltage and turning off the output pass circuit when the voltage produced by the current to voltage converter is larger than or equal to the threshold voltage.