Power Control Circuit With MOSFET Startup Shorting
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Solution Overview
Problem
Conventional LED driving devices face challenges in reliably starting up their internal reference voltage generating circuits during device startup.
Innovation Solution
A power control device is designed with a MOS transistor configured as an N-channel MOSFET, connecting a first terminal with a common voltage to a second terminal connectable to a ground application terminal, and an internal reference voltage generating circuit that short-circuits these terminals when the input supply voltage is turned on, ensuring reliable startup of the internal reference voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the internal reference voltage generating circuit is designed to operate with the input supply voltage, then the circuit can generate the required reference voltage, but the circuit fails to start up reliably when the device is powered on
Solution Approach 1:
The patent applies preliminary action by short-circuiting the first and second terminals at the moment of power-on before normal operation begins. This preliminary short-circuit action ensures that the internal reference voltage generating circuit receives the necessary voltage conditions to start up reliably, and the transistor is subsequently turned off to restore normal circuit operation.
2Reliability
If the MOS transistor is used to short-circuit terminals during startup, then the internal reference voltage generating circuit starts reliably, but additional components are introduced into the circuit
Solution Approach 1:
The patent applies universality by designing the MOS transistor to serve multiple functions: it acts as a switch to short-circuit terminals during startup to enable reliable circuit initialization, and simultaneously functions as part of the normal circuit operation when turned off. This multi-functionality reduces the need for separate dedicated startup components.
Data Source
AI summary
A power control device is configured to control a power circuit that generates an output voltage based on an input supply voltage relative to a ground, and includes a first terminal fed with a common voltage, a second terminal connectable to an application terminal for the ground, a P-type substrate fed with the common voltage, a MOS transistor connected between the first and second terminals and configured with an N-channel MOSFET, and an internal reference voltage generating circuit configured to generate, based on the input supply voltage, an internal reference voltage relative to the common voltage. When the input supply voltage is turned on, the MOS transistor is turned on and thereby the first and second terminals are short-circuited together.