Timing Unit for USB Peripheral Power-Up Compliance
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Solution Overview
Problem
Peripheral devices, such as PDAs and printers, face challenges in powering up within the 100 ms time frame required by the USB standard when a battery pack is inserted, as they rely on human intervention to activate the power switch, making them non-compliant with USB power management standards.
Innovation Solution
A device and method that includes a power management unit (PMU) with input terminals for electrical coupling to a battery pack and processor communication terminals, featuring a timing unit that sends electrical signals to initiate power-up after a configurable time t1, ensuring completion within a configurable time t2, which is less than the USB standard time of 100 ms, and providing forced reset and suspend functionality compliant with USB standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the peripheral device relies on human intervention to activate the power switch, then the device structure remains simple, but the device fails to meet USB power management standards requiring power-up within 100 ms
Solution Approach 1:
The timing unit automatically detects battery pack insertion and initiates the power-up sequence without requiring human intervention. The system serves itself by monitoring the battery connection status and autonomously activating the processor power-up, thereby achieving USB standard compliance while maintaining operational simplicity
Solution Approach 2:
The timing unit is pre-configured with USB standard time parameters (100 ms) and is ready to immediately initiate power-up upon detecting battery insertion. This preliminary preparation ensures that the power-up sequence begins within the required time frame, meeting USB compliance requirements
2Reliability
If the processor is powered up immediately upon battery insertion, then USB standard compliance is achieved, but power consumption increases before the device is ready to operate
Solution Approach 1:
The timing unit dynamically adjusts the power-up initiation based on the detected battery insertion event. It introduces an optimized delay period after insertion before activating the processor, balancing the need to meet USB timing requirements while minimizing unnecessary power consumption during the preparation phase
Solution Approach 2:
The system changes the timing parameter for processor activation from immediate (0 ms) to an optimized delay period that satisfies USB standards. This parameter adjustment ensures compliance while reducing power waste by activating the processor only when necessary and at the optimal moment
3Reliability
If the device adds automatic detection and timing control functionality, then USB standard compliance is achieved, but the device complexity increases
Solution Approach 1:
The timing unit is designed to perform multiple functions: detecting battery pack insertion, measuring the delay period, initiating processor power-up, and ensuring USB standard compliance. By consolidating these functions into a single multi-functional component, the added complexity is minimized while achieving comprehensive USB power management capability
Data Source
AI summary
A device and method for making a peripheral device compliant with a power management standard, such as the USB standard, are described. The device includes a power management unit (PMU) and a timing unit. The PMU is coupled to a battery pack and to a processor of the peripheral device, and manages power allocated to the processor. The timing unit sends electrical signals to the input terminals of the PMU when the battery pack is connected to the peripheral device. The electrical signals activate the processor via the PMU. The timing unit sends the electrical signals before a configurable time from the time when the battery pack is connected to the peripheral device.