Synchronous Buck Regulator Negative Voltage Protection
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Solution Overview
Problem
Conventional synchronous Buck regulators fail to effectively manage negative voltage events during overvoltage corrections, which can be destructive to information handling system components, and rely on costly and space-consuming power schottky diodes for protection.
Innovation Solution
A system and method that utilize a negative voltage protection MOSFET driver to selectively control the synchronous MOSFET based on the cause of the overvoltage event, preventing excessive negative voltage without adding additional hardware like diodes, by determining if the event is due to a failed control MOSFET or other conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power schottky diode is connected across the output of the regulator to act as a reverse-polarity clamp, then negative voltage protection is provided, but the cost increases and printed circuit board area is consumed
Solution Approach 1:
The patent combines the negative voltage protection function with the existing synchronous MOSFET and control logic in the Buck regulator, eliminating the need for a separate power schottky diode. The control circuit integrates multiple functions including overvoltage detection, negative voltage detection, and selective MOSFET control into a single controller, thereby reducing component count and PCB area while maintaining protection reliability.
Solution Approach 2:
The synchronous MOSFET and control circuit are designed to perform multiple functions: normal voltage regulation, overvoltage protection by discharging the output capacitor, and negative voltage protection by selectively turning off the MOSFET. This multi-functionality eliminates the need for dedicated protection components like power schottky diodes, reducing both cost and PCB area.
2Reliability
If a power schottky diode is connected across the output of the regulator to act as a reverse-polarity clamp, then negative voltage protection is provided, but the manufacturing cost and difficulty increase
Solution Approach 1:
The protection function is merged into the existing regulator circuitry, eliminating the need to source, stock, and assemble additional protection diodes. This reduces manufacturing complexity and cost while maintaining the required protection level.
Solution Approach 2:
The regulator's control circuit automatically detects negative voltage conditions and responds by turning off the synchronous MOSFET, providing self-protection without requiring external protection components. This self-service capability simplifies the manufacturing process and reduces assembly steps.
3Speed
If the synchronous MOSFET is turned on to rapidly discharge the output capacitor during an overvoltage event, then the output voltage is reduced, but a negative voltage output occurs
Solution Approach 1:
The control circuit continuously monitors the output voltage polarity and uses this feedback to control the synchronous MOSFET. When negative voltage is detected, the feedback signal triggers the MOSFET to turn off, preventing further voltage discharge and eliminating the harmful negative voltage effect while maintaining rapid correction capability.
Solution Approach 2:
The synchronous MOSFET is dynamically controlled based on real-time voltage conditions. During overvoltage events, the MOSFET is turned on for rapid discharge, but when negative voltage is detected, the MOSFET is immediately turned off. This dynamic control allows the system to achieve fast correction speed while avoiding the harmful side effect of excessive negative voltage.
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
This approach effectively avoids excessive negative voltage events in synchronous Buck regulators during overvoltage corrections, simplifying regulator design, reducing costs, and minimizing printed circuit board space, while ensuring the continued operation of information handling system components.
Implementation Method 1
the regulator controller turns on the synchronous MOSFET to rapidly discharge an output capacitor of the LC tank circuit and reduce the output voltage
Implementation Method 2
A negative voltage protection MOSFET driver detects if the correction to the overvoltage results in a negative voltage
Data Source
AI summary
A synchronous Buck voltage regulator accepts an input voltage to provide a regulated output voltage to an information handling system processing component, such as a CPU. Input voltage is regulated by a control MOSFET, a synchronous MOSFET and a regulator controller that controls the output by controlling the control and synchronous MOSFETs. The synchronous MOSFET handles overvoltage events output from the control MOSFET by interfacing an inductor-capacitor tank circuit to reduce the overvoltage. A negative voltage protection MOSFET driver associated with the regulator controller monitors for negative voltage events that result from the interfacing of the inductor-capacitor tank circuit and selectively decouples the inductor-capacitor tank circuit if the negative voltage event is associated with a predetermined condition. The negative voltage protection MOSFET driver maintains the interface of the inductor-capacitor tank circuit if the overvoltage event is associated with a failed control MOSFET.