Reset-Controlled Power Supply Switching for Stable Startup Voltage
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Solution Overview
Problem
In semiconductor devices, ensuring that the internal power supply voltage reliably rises to the normal operating voltage during startup is challenging, particularly when the control circuit cannot operate due to low voltage levels, leading to potential circuit operation issues and increased power consumption.
Innovation Solution
A power supply device with a switching circuit and control circuit configuration that allows the switching circuit to transition to an off state independently of the control circuit operation by using a reset signal, ensuring the internal power supply voltage is cut off until it reaches the normal operating voltage, thereby stabilizing it at the desired level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control circuit operates at low voltage levels during startup, then the switching circuit can be controlled to transition states, but the internal power supply voltage may not reliably rise to normal operating voltage and circuit operation issues occur
Solution Approach 1:
The reset circuit generates a reset signal before the control circuit becomes operational, during the startup phase when voltage is still rising. This reset signal is applied to the switching circuit in advance to ensure it remains in a known state (first state) until the control circuit is fully operational and can properly manage voltage transitions. This preliminary action prevents unpredictable behavior during the critical startup period.
Solution Approach 2:
The reset circuit acts as an intermediary between the power supply voltage source and the switching circuit during startup. It mediates the transition by providing a reset signal that overrides normal control signals until the internal power supply voltage reaches a stable level. This intermediary function simplifies the overall design by eliminating the need for complex low-voltage control considerations.
2Loss of energy
If the switching circuit transitions to off state during startup, then power consumption is reduced, but the internal power supply voltage cannot be supplied to circuits requiring it
Solution Approach 1:
The reset circuit applies a preliminary anti-action by forcing the switching circuit to remain in the first state (power supply enabled) during the critical startup period when voltage is rising. This prevents the switching circuit from prematurely transitioning to the off state, ensuring that power is continuously supplied to circuits that need it during voltage stabilization, while still allowing for controlled power management once stability is achieved.
3Reliability
If the reset signal is continuously applied to the switching circuit, then the internal power supply voltage is reliably supplied, but the switching circuit cannot transition to off state for power saving
Solution Approach 1:
The reset signal is designed to be dynamic rather than static - it is automatically generated during startup when voltage rises and is automatically cancelled when the internal power supply voltage reaches a stable level. This dynamic behavior allows the switching circuit to transition from being forced into the first state during startup to being freely controllable during normal operation, enabling both reliable startup and power-saving mode transitions.
Solution Approach 2:
The reset circuit incorporates feedback by monitoring the internal power supply voltage level and automatically adjusting its reset signal output accordingly. When voltage is unstable during startup, the reset signal is active; when voltage stabilizes, the reset signal is cancelled. This feedback mechanism ensures reliable power supply during critical periods while enabling energy-saving operations during stable periods.
Data Source
AI summary
A power supply device includes a switching circuit and first and second control circuits. The switching circuit is between a regulator circuit and a terminal and is configured to transition between a first state in which a second power supply voltage is supplied to the terminal and a second state in which supply of the second power supply voltage to the terminal is cut off. The first control circuit is configured to output a reset signal that is set to a first voltage or a second voltage. The second control circuit is configured to be driven by the second power supply voltage and to perform control so that the switching circuit transitions to the first or second state when the reset signal is at the first voltage. The switching circuit is configured to switch to the second state when the reset signal is set to the second voltage.