Power Management Circuit for USB Enumeration and Battery Charging
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Solution Overview
Problem
Existing electronic apparatuses face system failures and inadequate battery charging due to insufficient or unstable power supply from external devices via USB, preventing normal enumeration and efficient battery charging.
Innovation Solution
An electronic apparatus with a power receiving unit, control signal generating units, and a charge control unit that manages power supply from an external device, allowing for efficient battery charging by switching between power sources and controlling charging based on battery voltage, ensuring stable power delivery and completion of USB enumeration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power is received from an external apparatus through USB cable, then charging function is enabled, but system failure occurs when power supply ability is insufficient or unstable
Solution Approach 1:
The electronic apparatus performs USB enumeration using only battery power before connecting to external power supply. This preliminary action ensures that the enumeration process completes successfully with stable battery power, avoiding system failures that would occur if enumeration attempted during unstable external power supply
Solution Approach 2:
The power supply process is segmented into distinct phases: first using battery power for enumeration, then switching to external power supply for charging. This segmentation allows each process to use the most appropriate power source, ensuring reliable enumeration while enabling efficient charging
2Loss of time
If enumeration cannot be completed normally, then power supply from external apparatus is limited, but charging time cannot be shortened
Solution Approach 1:
By completing enumeration beforehand using battery power, the apparatus ensures that the USB connection is properly established and recognized. This preliminary enumeration enables the external apparatus to supply maximum power (500mA at 5V) for charging, thereby shortening charging time
3Productivity
If power is used for enumeration during charging, then external power supply is utilized, but system stability decreases when external power is insufficient
Solution Approach 1:
The patent segments the power usage into distinct functional phases: battery power is used exclusively for enumeration and system operations, while external power supply is dedicated to charging the battery. This segmentation prevents system instability by ensuring that enumeration always occurs with stable battery power, while charging efficiency is maximized using external power
Data Source
AI summary
An electronic apparatus includes a power receiving unit that receives power from an external apparatus connected to an interface unit, a first generating unit that generates a first control signal, a second generating unit that generates a second control signal, a third generating unit that generates a third control signal, a fourth generating unit that generates a fourth control signal using the first to third control signals, a charge control unit that charges a battery with power received from the external apparatus when the fourth control signal is in a low state, and that stops charging the battery when the fourth control signal is in a high state, and a power supply unit that starts supplying power from the battery to the second generating unit when the fourth control signal is changed into a high state.