Differential Power Supply Startup Switching for Stable High Current
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Solution Overview
Problem
The existing power supply circuit struggles to provide smooth startup and high current capability while maintaining stable voltage, as the output transistor's capability is switched between startup and normal operation, leading to unstable voltage supply due to unchanged amplifier configuration and impedance.
Innovation Solution
A power supply circuit with a differential amplifying unit and an output stage featuring two tail current sources and output transistors, controlled by a controller to switch between different configurations during startup and after startup, ensuring smooth startup and high current capability with stable voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the output transistor's capability is increased to improve current driving capability, then the current driving capability is improved, but rush current during startup and overshoot of output voltage occur
Solution Approach 1:
The patent applies dynamics by making the output transistor's capability adjustable rather than fixed. The circuit dynamically switches between a first output transistor (lower capability) during startup and a second output transistor (higher capability) during normal operation. This dynamic adjustment allows the system to optimize performance for different operational phases, preventing rush current and voltage overshoot during startup while providing high current capability during normal operation.
Solution Approach 2:
The patent implements periodic action through a startup completion detection circuit that monitors the output voltage and triggers switching between different transistor configurations. During the startup period, the first transistor configuration is used; once startup is complete, the circuit transitions to the second transistor configuration. This periodic switching based on operational phase ensures stable voltage during startup and high current capability during normal operation.
2Reliability
If the output transistor's capability is reduced during startup to prevent rush current and voltage overshoot, then output voltage stability is improved, but current driving capability becomes insufficient
Solution Approach 1:
The patent resolves this contradiction through dynamic capability adjustment. The output stage includes multiple transistors with different capability levels that are selectively activated based on the operational phase. During startup, the lower-capability first transistor is used to ensure voltage stability; after startup completion, the higher-capability second transistor is activated to provide sufficient current driving capability. This dynamic switching eliminates the need to compromise between stability and capability.
Solution Approach 2:
The patent uses periodic action through phase-based switching. The startup completion detection circuit identifies when the output voltage has stabilized, triggering a transition from the first transistor configuration to the second. This periodic switching ensures that the appropriate transistor capability is applied at the appropriate time, maintaining voltage stability during startup and providing high current capability during normal operation.
3Device complexity
If the amplifier configuration remains unchanged during and after startup, then device complexity is reduced, but the power supply circuit cannot supply stable voltage
Solution Approach 1:
The patent applies dynamics by making the amplifier configuration adjustable rather than fixed. The circuit includes a first amplifier configuration during startup and a second amplifier configuration after startup completion. The startup completion detection circuit triggers the switching between these configurations. This dynamic adjustment allows the system to optimize amplifier characteristics for different operational phases, ensuring stable voltage supply while managing complexity through selective configuration changes.
Data Source
AI summary
A differential amplifying unit includes a first input transistor and a second input transistor forming a differential pair, and a first tail current source and a second tail current source. An output stage includes a first output transistor and a second output transistor that can be driven by an output of the differential amplifying unit. A controller performs control such that during startup, a load is driven by the first tail current source and the first output transistor, and such that after startup, the load is driven by the first tail current source, the second tail current source, the first output transistor, and the second output transistor.