Bidirectional Interface Circuitry for Accessory Power Detection
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Solution Overview
Problem
There is a need for interface circuits that can detect the presence of accessories, determine if they can provide or receive power, communicate power transfer details, and transfer power using a limited number of pins, while simplifying connectors and reducing pin counts to make them more space-efficient.
Innovation Solution
The use of a host device with a connector having a bidirectional data pin, a bidirectional power pin, and a ground pin, along with detection circuitry that employs pull-up and pull-down resistors to detect the presence of accessories and negotiate power transfer, allowing for efficient power management and communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the pin count is reduced to simplify connectors and make them smaller, then space efficiency and simplicity are improved, but the ability to detect accessory presence, determine power capability, communicate power transfer details, and transfer power is compromised
Solution Approach 1:
The patent makes the data pin bidirectional, allowing it to serve both data communication and power capability detection functions. The same physical pin is used for different purposes depending on the operational context, enabling the connector to maintain full functionality with fewer pins.
Solution Approach 2:
The patent combines data communication and power detection functions into a single bidirectional data pin. By merging these functions, the connector achieves the same capabilities with reduced pin count, directly resolving the contradiction between simplicity and functionality.
2Reliability
If voltage is continuously applied to connector contacts to ensure reliable power transfer, then power transfer reliability is improved, but corrosion of connector pins increases
Solution Approach 1:
The patent implements periodic voltage application through alternating pull-up and pull-down resistor connections. Voltage is applied in pulses rather than continuously, which maintains reliable power transfer capability while significantly reducing cumulative corrosion effects on connector contacts.
Solution Approach 2:
The patent uses feedback through detection circuitry that monitors the state of connector contacts and adjusts voltage application accordingly. The system detects when power transfer is established and reduces or stops voltage application, preventing unnecessary corrosion while maintaining reliable power transfer when needed.
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
Enables efficient detection and management of power transfer between devices with a reduced pin count, preventing corrosion and ensuring reliable data transmission, while maintaining user safety by limiting average voltage on connector contacts.
Implementation Method 1
a power consuming accessory may include a pull-down resistor on its data pin. The presence of this pull-down resistor on the data pin may identify the accessory as a power consuming accessory.
Implementation Method 2
The host may have a connector with a bidirectional data pin, a bidirectional power pin, and a ground pin. The host may connect to the accessory using these pins via a cable, or these pins may make a direct physical connections with corresponding pins of the accessory.
Data Source
AI summary
Interface circuits that may utilize a limited number of pins to detect a presence of an accessory, determine whether the accessory can provide or receive power, communicate with the accessory regarding at least that transfer of power, and transfer power accordingly. One example may provide detection circuitry for a host that may detect the presence of a pull-down resistor on a data pin of an accessory. The pull-down may indicate that a power consuming accessory has been connected. This example may detect the presence of power on a power pin. The presence of the power on the power pin may indicate that a power providing accessory has been connected.