USB Control System Voltage Segmentation for Leakage Reduction
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Solution Overview
Problem
USB controllers face excessive power consumption during the suspending mode due to leakage currents, exceeding the maximum current level defined in the USB Specification, despite deactivation of internal blocks.
Innovation Solution
A USB control system comprising a first and second voltage adjuster, a control switch, and a PHY unit, which supplies a first internal voltage during suspending mode and interrupts the second internal voltage, using signal holders to maintain signal levels and a backup memory for state data, allowing for efficient mode transitions between suspending and resuming modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the USB controller enters suspending mode by deactivating internal blocks, then power consumption is reduced, but leakage currents still cause excessive power consumption exceeding USB Specification limits
Solution Approach 1:
The voltage supply system is segmented into multiple independent voltage adjusters (first voltage adjuster 210, second voltage adjuster 230) that can be independently controlled. This allows selective power supply to different internal blocks, enabling the controller to supply voltage only to essential blocks during suspending mode while completely cutting power to non-essential blocks, thereby reducing total leakage current below USB Specification limits.
Solution Approach 2:
Different internal blocks are assigned different power supply qualities through the control switch 225 and separate voltage adjusters. Essential blocks receive continuous power supply while non-essential blocks receive interrupted power supply during suspending mode. This local differentiation of power quality allows the system to maintain minimum functionality while achieving ultra-low power consumption that meets USB current limits.
2Reliability
If all internal voltage is supplied to all blocks during suspending mode, then blocks remain operational, but current consumption exceeds maximum USB Specification level
Solution Approach 1:
The power supply is segmented into first internal voltage INT_VDD1 from voltage adjuster 210 and second internal voltage INT_VDD2 from voltage adjuster 230. The control switch 225 selectively connects or disconnects the second voltage adjuster 230 based on operation mode. During suspending mode, only the first voltage adjuster 210 supplies power to essential blocks, while the second voltage adjuster 230 is disconnected, reducing total current consumption to meet USB Specification limits while maintaining essential block operations.
3Use of energy by moving object
If the control switch interrupts external voltage to the second voltage adjuster, then power consumption is reduced, but mode transition time increases
Solution Approach 1:
Both voltage adjusters 210 and 230 are pre-configured and ready before mode transitions occur. The first voltage adjuster 210 continuously supplies INT_VDD1 to essential blocks, while the second voltage adjuster 230 maintains readiness with INT_VDD2. When transitioning from active to suspending mode, the control switch 225 simply disconnects the second voltage adjuster 230 without requiring gradual ramping down, enabling rapid mode transition while maintaining low power consumption.
Data Source
AI summary
A USB control system includes a first voltage controller, a control switch, a second voltage controller, and a PHY unit. The first voltage controller outputs a first internal voltage from an external voltage and a reference voltage, and the control switch regulates supplying and suspending the external voltage. The second voltage controller outputs a second internal voltage from the reference voltage and the external voltage applied through the control switch, and the PHY unit receives a request from a host using the first or second internal voltage as a voltage source. The power for certain internal blocks is suspended to reduce power consumption in the USB control system during a power-saving mode.