DC-DC Converter Controller Phase Node Voltage Sensing
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Solution Overview
Problem
Conventional DC-DC converter controllers require multiple pins to receive input and output voltages, leading to increased chip area and pin count, which complicates the design and efficiency of the power supply controller.
Innovation Solution
A PWM controller with a first and second sense circuit to sense signals from a phase node, generating signals corresponding to input and output voltages, and a PWM generator to control transistors, reducing the need for separate pins to receive input and output voltages by integrating sensing and control functions within an IC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple pins are used to receive input and output voltages separately, then voltage sensing accuracy is improved, but chip area and pin count increase
Solution Approach 1:
The patent merges the sensing of input voltage and output voltage into a single pin by using a phase node as a common sensing point. The first sense circuit senses the input voltage through the phase node when the first transistor is turned on, while the second sense circuit senses the output voltage through the same phase node when the first transistor is turned off. This combining approach reduces the pin count from multiple pins to a single shared pin while maintaining voltage sensing accuracy through timing-based differentiation.
Solution Approach 2:
The phase node serves multiple functions: it acts as the switching node for the power transistors, the sensing point for both input and output voltage detection, and the reference point for PWM generation. By making the phase node multi-functional, the patent eliminates the need for separate dedicated pins for each function, thereby reducing overall pin count and chip area while preserving measurement precision.
2Measurement precision
If multiple pins are used to receive input and output voltages separately, then voltage sensing accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple voltage sensing functions into a single integrated circuit with shared sensing infrastructure. The first and second sense circuits both utilize the phase node as their sensing point, eliminating the need for separate external pins and reducing the complexity of external circuit connections. The controller integrates the PWM generation, voltage sensing, and transistor control functions in a unified architecture.
Solution Approach 2:
The phase node is designed as a universal interface that handles multiple functions: power switching, input voltage sensing, output voltage sensing, and PWM signal reference. This multi-functionality reduces the number of separate components and connections needed, thereby simplifying the overall device design while maintaining the ability to accurately sense both input and output voltages.
3Reliability
If separate pins are used for input and output voltage sensing, then sensing reliability is improved, but pin count increases
Solution Approach 1:
The patent merges the sensing functions for input and output voltages into a single pin interface while maintaining reliability through temporal separation. The controller samples the phase node voltage at different times: when the first transistor is on for input voltage sensing, and when it is off for output voltage sensing. This time-division multiplexing approach allows reliable sensing of both voltages through a single pin without the need for multiple simultaneous sensing paths.
Solution Approach 2:
The voltage sensing operates periodically synchronized with the switching cycle of the transistors. The first sense circuit activates during the on-period of the first transistor to sense input voltage, while the second sense circuit activates during the off-period to sense output voltage. This periodic, time-division approach ensures reliable sensing of both voltages while using only a single shared pin, reducing pin count without compromising sensing reliability.
Data Source
AI summary
A PWM controller of a DC-DC converter is provided. The DC-DC converter converts an input voltage into an output voltage and comprises an output inductor coupled between an output of the DC-DC converter and a phase node. A first sense circuit senses a signal from the phase node to generate a first signal corresponding to the input voltage. A second sense circuit senses the signal from the phase node to generate a second signal corresponding to the output voltage. A PWM generator controls a first transistor and a second transistor of the DC-DC converter according to the first and second signals. The first transistor is coupled between the input voltage and the phase node, and the second transistor is coupled between the phase node and a ground.