USB VBUS Discharge Control to Limit Die Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing USB power delivery systems face thermal reliability issues due to high current discharge of VBUS voltage, leading to increased die temperature and potential reliability risks, especially in USB Type-C interfaces, which are addressed by external power transistors controlled by GPIO signals, increasing die area and cost.
Innovation Solution
A method and apparatus for discharging USB VBUS voltage using a transistor configuration controlled by a USB-PD controller, applying incrementally increasing voltage reference values to an amplifier until a discharge trigger point is reached, then stopping the increment, utilizing existing components and avoiding on-die heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If on-the-die VBUS discharge is used, then the discharge function is integrated, but power dissipation increases and die temperature rises
Solution Approach 1:
The patent extracts the VBUS discharge function from the integrated circuit die and implements it using an external transistor. The discharge path is formed by the external transistor's drain-source channel, separating the high-power discharge operation from the sensitive IC die, thereby eliminating on-die heating while maintaining integrated functionality through GPIO control.
Solution Approach 2:
The patent introduces an external transistor as an intermediary component between the VBUS capacitor and ground. This intermediary handles the high-current discharge path, acting as a buffer that protects the IC die from thermal stress while enabling the discharge function to be controlled by the USB controller through GPIO signals.
2Temperature
If external power transistors are employed, then die temperature is controlled, but die area and cost increase
Solution Approach 1:
The patent extracts the power transistor from the IC die and places it externally, eliminating the need for large die area allocation for power handling components. The external transistor assumes the role of managing high-power discharge operations, allowing the IC die to maintain a compact footprint while achieving effective thermal control.
3Device complexity
If resistive-type discharge is used, then discharge operation is simple, but current increases at higher VBUS voltage leading to higher power dissipation
Solution Approach 1:
The patent replaces the traditional resistive discharge mechanism with a transistor-based electronic switch. Instead of using a resistor that dissipates power continuously according to I²R losses, the external transistor acts as a controlled switch that can efficiently manage the discharge current, reducing power dissipation while maintaining operational simplicity through GPIO control.
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 effectively discharges VBUS voltage within USB-PD specifications without causing thermal issues, saving space, reducing die cost, and eliminating the need for additional external components, while maintaining reliability and flexibility.
Implementation Method 1
The amplifier outputs a voltage signal to a gate driver that controls a gate of a transistor
Data Source
AI summary
Techniques are provided for discharge of a universal serial bus voltage. A determination is made that the universal serial bus voltage has exceeded a threshold. Accordingly, initiation of a discharge operation is triggered to discharge the universal serial bus voltage. The discharge operation includes applying incrementally increasing voltage reference values according to a periodic interval to an amplifier until a discharge trigger point is reached. The amplifier outputs a voltage signal to a gate driver that controls a gate of a transistor that provides a discharge path for the universal serial bus voltage to discharge. In response to reaching the discharge trigger point, the incremental increasing of the voltage reference values applied to the amplifier is stopped.