Bandgap Startup Circuit for Reliable High-Voltage Regulator Restart
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Solution Overview
Problem
Existing voltage regulators in portable and battery-powered systems face challenges with reliable startup and shutdown due to slow power supply input voltage changes and high power consumption, leading to potential circuit shutdown and failure to restart.
Innovation Solution
A self-starting internal supply voltage regulator with a bandgap reference detection circuit that includes a startup circuit and reference generation circuit, utilizing transistors and resistors to monitor and regulate the bandgap reference voltage, providing a 'Reference Ready' signal when within specifications, and using a zero-threshold NFET and JFET to manage voltage and current efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply input voltage increases slowly, then the circuit startup may fail, but increasing the voltage rise time increases power consumption and delays startup
Solution Approach 1:
The startup circuit activates preliminary action by detecting the power supply voltage level and condition before the main reference generation circuit is fully operational. It prepares the bandgap reference circuit by enabling it early in the startup sequence, ensuring that when the main circuit activates, the reference voltage is already stabilized and ready, thus preventing startup failures without requiring prolonged voltage rise times that would increase power consumption.
2Loss of energy
If the circuit shuts down when input voltage drops below threshold, then power consumption is reduced, but the circuit may fail to restart after voltage is restored
Solution Approach 1:
The startup circuit implements feedback by continuously monitoring the power supply input voltage and the bandgap reference voltage. When the input voltage drops below the threshold, the circuit shuts down to reduce power consumption. When the voltage is restored, the feedback mechanism detects the voltage recovery and automatically re-enables the bandgap reference circuit, ensuring reliable restart without manual intervention. This feedback loop maintains both energy efficiency during shutdown and restart capability.
3Power
If a traditional reference generation circuit is used, then voltage regulation is achieved, but the circuit occupies excessive silicon area and consumes high power
Solution Approach 1:
The patent merges the startup circuit functionality with the bandgap reference generation circuit into a single integrated structure. The startup circuit shares transistors and resistors with the reference generation circuit, eliminating the need for separate dedicated startup components. This merging reduces the overall silicon area occupied by the voltage regulator while maintaining both startup and voltage regulation functions. The shared components are designed to serve dual purposes: initializing the circuit during startup and providing stable reference voltage during normal operation.
Data Source
AI summary
Described embodiments include a circuit for voltage regulator startup. The circuit includes a voltage regulation circuit having first and second regulator inputs and a regulator output. A startup circuit has a startup input coupled to the first regulator input, and a startup output. A reference generation circuit has first and second reference inputs and first and second reference outputs. The first reference input is coupled to the regulator output. The second reference input is coupled to the startup output, and the first reference output is coupled to a reference output terminal and to the second regulator input. A reference detection circuit has a first detection input coupled to the regulator output, and a second detection input coupled to the second reference output, and provides a reference ready signal responsive to a reference voltage being within a reference specification.