OR-ing MOSFET Current Sensing via On-Resistance
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Solution Overview
Problem
Existing current sensing methods in information handling systems, such as bulky resistor shunts, consume power, occupy significant space, generate heat, and increase manufacturing costs, while being inefficient for monitoring power supply output current.
Innovation Solution
Incorporating an OR-ing metal-oxide-semiconductor field effect transistor (MOSFET) coupled with a controller in the power supply unit to measure voltage signals and estimate output current, reducing the need for bulky resistor shunts and improving power supply monitoring efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bulky resistor shunts are used to measure output current, then current measurement can be achieved, but power consumption increases, space requirements increase, heat output increases, and manufacturing cost increases
Solution Approach 1:
The patent merges the current sensing function with the existing OR-ing MOSFET structure by utilizing the MOSFET's inherent on-resistance as the sensing element. This integration eliminates the need for separate resistor shunts, thereby reducing power consumption while maintaining current measurement capability through voltage sensing across the MOSFET's channel.
2Measurement precision
If bulky resistor shunts are used to measure output current, then current measurement can be achieved, but the space occupied increases
Solution Approach 1:
The sensing function is merged into the OR-ing MOSFET's channel region, eliminating the need for discrete resistor shunts that occupy significant PCB space. The voltage sensing is performed directly across the MOSFET's on-resistance, utilizing the minimal space already allocated for the MOSFET device itself.
3Measurement precision
If bulky resistor shunts are used to measure output current, then current measurement can be achieved, but heat output increases
Solution Approach 1:
The patent combines the current sensing function with the OR-ing MOSFET's normal conduction path. The voltage drop across the MOSFET's on-resistance during normal operation is used for sensing, eliminating separate power-dissipating resistor shunts and thereby reducing overall heat generation in the power supply circuit.
4Measurement precision
If bulky resistor shunts are used to measure output current, then current measurement can be achieved, but manufacturing cost increases
Solution Approach 1:
The patent integrates current sensing functionality into the existing OR-ing MOSFET and controller architecture, eliminating the need for additional resistor shunt components. This reduction in component count simplifies the bill of materials, reduces assembly steps, and lowers overall manufacturing costs while maintaining accurate current measurement through the controller's existing voltage sensing capabilities.
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 solution enhances current sensing in power supplies by reducing power consumption, space requirements, and manufacturing costs, while providing accurate and efficient monitoring of output current, thereby improving power management in information handling systems.
Implementation Method 1
A voltage across such resistor shunts may be measured, and by knowing the resistance of such resistor shunts, the current may be determined from the voltage based on Ohm's law
Data Source
AI summary
In accordance with embodiments of the present disclosure, a power supply unit may include one or more stages including an output stage configured to generate a direct-current output voltage at an output of the power supply, an OR-ing metal-oxide-semiconductor field effect transistor (MOSFET) coupled between the output stage and the output, and a controller. The controller may be configured to measure a signal indicative of a voltage associated with the OR-ing MOSFET and determine an estimated output current of the power supply based on the signal.