Synchronous Buck Converter External Clock Cycle-by-Cycle Control
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Solution Overview
Problem
Existing DC-DC converters require multiple secondary windings and complex rectification systems for achieving multiple output voltages at different power levels, making them costly and space-intensive.
Innovation Solution
A synchronous buck converter with a control circuit that uses an external clock signal for cycle-by-cycle operation, eliminating the need for amplifiers and oscillators, and allowing the step-down stages to operate independently on the secondary side with high-power feedback on the primary side, utilizing PWM modulation and a shunt regulator for error processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple secondary windings and rectification systems are used to achieve multiple output voltages, then output voltage versatility is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent applies multi-functionality by using a single secondary winding that serves multiple purposes through a synchronous buck converter circuit. This circuit can generate multiple different output voltages from one input voltage by controlling the duty cycle of the switches, eliminating the need for multiple separate rectification systems for different voltage outputs.
Solution Approach 2:
The patent segments the voltage regulation function into separate synchronous buck converter stages. Instead of having one complex rectification system for multiple voltages, the system divides the conversion into multiple simpler stages, each handling specific voltage step-down operations independently, thereby reducing overall system complexity.
2Adaptability or versatility
If multiple secondary windings and rectification systems are used, then multiple output voltages are achieved, but manufacturing cost increases
Solution Approach 1:
The synchronous buck converter circuit serves as a universal voltage conversion stage that can produce multiple different output voltages from a single secondary winding. This multi-functional approach reduces the total component count and simplifies manufacturing processes, thereby lowering production costs compared to implementing separate rectification systems for each voltage level.
3Area of stationary object
If a synchronous buck converter with external clock is used, then control IC area is reduced, but synchronization capability must be maintained
Solution Approach 1:
The patent extracts the clock generation function from the control IC and uses an external clock source instead. This removes the oscillator and related control logic from the IC, significantly reducing its area. The external clock provides the necessary synchronization signal to the synchronous buck converter, maintaining the required coordination between primary and secondary sides without embedding the clock circuitry in the IC.
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
The solution provides a simple, cost-effective, and compact step-down converter that reduces electromagnetic interference (EMI) and optimizes capacitor usage, enabling efficient operation with reduced control IC area and easy integration with existing controller products.
Implementation Method 1
The control circuit operates in a cycle by cycle operation generating PWM modulation synchronous to the external clock source
Data Source
AI summary
A DC-DC voltage converter having a switching stage including high- and low-side switches connected in series at a switched node across a DC voltage bus; a control circuit; and a feedback loop connected between an output of the switching stage and an input of the control circuit, the control circuit having a clock signal input and including an error processing circuit coupled to the input for detecting an output of the feedback loop, the control circuit turning OFF the low-side switch and turning ON the high-side switch when the clock signal is detected. The control circuit operates in a cycle-by-cycle operation generating PWM modulation synchronous to the external clock source.