SenseFET Current Regulator Internal Off-Time Estimation
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Solution Overview
Problem
Current semiconductor power supply controllers require external components like current sense transformers and resistors to measure current, increasing costs and power dissipation.
Innovation Solution
A current regulator that uses a SenseFET type of power transistor with an internal off-time reference circuit to estimate the off-time based on the valley value of current, eliminating the need for external current sensing elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external current sensing elements (transformer or resistor) are used to measure current, then current measurement accuracy is improved, but system cost increases
Solution Approach 1:
The patent extracts the current sensing function from external components and relocates it internally within the controller. The senseFET's body diode and internal circuitry perform current sensing, eliminating the need for external current sense transformers or resistors. This reduces system cost while maintaining measurement capability.
Solution Approach 2:
The patent merges the current sensing function with the power switching function by using the senseFET's body diode, which is inherently part of the power transistor structure. This integration eliminates separate sensing components and reduces overall system complexity and cost.
2Measurement precision
If external current sensing elements (transformer or resistor) are used to measure current, then current measurement accuracy is improved, but power dissipation increases
Solution Approach 1:
The patent removes the external current sense resistor that causes power dissipation and replaces it with an internal sensing mechanism using the senseFET's body diode and voltage comparison circuitry, thereby eliminating the continuous power loss associated with resistive sensing.
Solution Approach 2:
The patent uses the senseFET's body diode, which naturally conducts during the off-time of the main transistor, to sense current without requiring additional power-dissipating components. The sensing is achieved through voltage comparison during brief intervals rather than continuous resistive measurement.
3Adaptability or versatility
If traditional current regulation method is used with external sensing components, then current control capability is maintained, but device complexity increases
Solution Approach 1:
The patent combines multiple functions (power switching, current sensing, and regulation control) into a single integrated controller device. The senseFET, voltage comparators, and control logic work together as an integrated system, eliminating the need for separate external sensing components and reducing overall device complexity.
Solution Approach 2:
The controller is designed as a universal integrated solution that performs power switching, current sensing, and regulation control all in one device. The senseFET structure provides both power handling and sensing capabilities, making the controller adaptable to various current regulation applications without requiring additional external components.
Data Source
AI summary
In one embodiment, a current regulator is configured to form a first signal representative of a current flow through a power switch and to use the first signal to determine an off-time of the power switch.