Power Supply Brownout Protection Circuit
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Solution Overview
Problem
Conventional power supplies with PFC circuits fail to provide sufficient time for microprocessors to process shutdown procedures during brownout conditions, leading to potential data loss due to immediate power cutoff without informing the microprocessor to initiate shutdown.
Innovation Solution
A power supply apparatus with a PFC circuit, bus capacitor, PWM circuit, and supervisor circuit that generates a power-good signal to allow the microprocessor to process shutdown procedures by disabling the PFC circuit's boosting operation and controlling the power-good signal when a brownout condition is detected, providing a delay for data saving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the standby circuit immediately disables the supply voltage of the PFC circuit, PWM circuit and supervisor circuit when a brownout condition occurs, then the power supply is protected from damage, but the microprocessor cannot process the shutdown procedure leading to data loss
Solution Approach 1:
The supervisor circuit continues to operate for a predetermined time after the brownout signal is generated, maintaining the supply voltage to the microprocessor long enough to allow the microprocessor to complete the shutdown procedure and save data before the power supply is fully disabled
Solution Approach 2:
The power good signal is asserted early when the brownout condition is detected, providing advance notification to the microprocessor to initiate the shutdown procedure before the actual power cutoff occurs
2Reliability
If the supervisor circuit is powered off immediately during brownout condition, then the brownout protection function is achieved, but the power-good signal cannot be output to inform the microprocessor to process shutdown
Solution Approach 1:
The supervisor circuit is designed to maintain operation for a predetermined time after brownout detection, providing a time window for the microprocessor to complete shutdown procedures before the supervisor circuit itself is powered off
Solution Approach 2:
The supervisor circuit's power supply timing is made dynamic and conditional - it continues operating based on the state of the power good signal and brownout condition, rather than being statically tied to the immediate brownout event
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
Enables timely processing of shutdown procedures by the microprocessor, preventing data loss during brownout conditions by maintaining power to the microprocessor and controlling the power-good signal to initiate shutdown, thus ensuring data integrity.
Implementation Method 1
a PFC circuit for correcting a power factor and boosting the input voltage
Implementation Method 2
a bus capacitor coupled to the PFC circuit for forming a bus voltage across itself
Implementation Method 3
a PWM circuit for transferring the bus voltage to an output voltage
Data Source
AI summary
An apparatus for a power supply with brownout protection and the method thereof are proposed. As a brownout condition occurs, the apparatus informs at least one microprocessor to process the shutdown process timely. The apparatus includes a power factor correction (PFC) circuit, and a bus capacitor generating a bus voltage by receiving an input voltage via the PFC circuit, and a PWM circuit generating multiple output voltages for the microprocessor, and a supervisor circuit generating a power-good signal in response to a proportional bus voltage, and a brownout circuit for disabling the boosting operation of the PFC circuit under a brownout condition. When the boosting operation is disabled, the bus voltage starts to fall. As the proportional bus voltage is lower than a threshold voltage, the supervisor circuit generates the power-good signal. Therefore, the microprocessor can process the shutdown procedure timely.