Distant PCB Integration Through Single-Wire PMIC Control
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Solution Overview
Problem
Conventional augmented reality and virtual reality systems face challenges in integrating physically distant printed circuit boards (PCBs) due to lengthy connectors and multi-drop configurations that impair signal integrity and performance, necessitating a new solution for inter-PCB power management integrated circuit (PMIC) communication.
Innovation Solution
A bi-directional, asynchronous, half-duplex, single-wire control interface is introduced for master-slave PMICs to facilitate power on triggers, fail-safe reset triggers, and slave processor-induced shutdown, integrating slave subsystems with a master subsystem for improved interconnectivity and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional multi-drop configurations and lengthy connectors are used to integrate physically distant PCBs, then device complexity is reduced and ease of manufacture is improved, but signal integrity deteriorates and performance is impaired
Solution Approach 1:
The patent combines multiple control signals (power on, shutdown, reset) into a single bi-directional control interface that operates in half-duplex mode. This merging of multiple functions into one interface maintains signal integrity by reducing the number of physical connections while preserving all necessary control capabilities between master and slave PMICs.
Solution Approach 2:
The control interface uses periodic time-division multiplexing where different control signals are transmitted at different time intervals on the same physical line. The master PMIC and slave PMIC take turns initiating communications during designated time windows, allowing multiple functions to share a single trace without signal interference.
2Ease of manufacture
If multiple separate control interfaces are used for PMIC functions, then signal integrity is maintained, but device complexity increases and manufacturing becomes more difficult
Solution Approach 1:
The single control interface is designed to perform multiple functions including power on triggering, shutdown control, and reset operations. The same physical trace and protocol handle all these different PMIC control functions, eliminating the need for separate dedicated interfaces for each function and significantly simplifying the overall system architecture.
Solution Approach 2:
Multiple control functions that would traditionally require separate physical interfaces are merged into one bi-directional control line. This consolidation reduces the number of connectors and traces needed, making the device easier to manufacture while maintaining all necessary control capabilities through intelligent time-division multiplexing.
3Reliability
If lengthy connectors are used to connect distant PCBs, then adaptability to different form factors is improved, but signal integrity and performance deteriorate
Solution Approach 1:
The control interface is segmented into distinct time windows for master-initiated communications and slave-initiated communications. This temporal segmentation allows the single physical interface to handle multiple control functions without interference, maintaining high performance even over longer connector lengths by reducing signal contention and interference.
4Device complexity
If a single-wire interface is used to integrate distant PCBs, then signal integrity is enhanced and device complexity is reduced, but the interface must handle multiple functions simultaneously
Solution Approach 1:
The single-wire control interface uses periodic time-division multiplexing to handle multiple functions. Different control signals are transmitted during different time intervals, with the master PMIC and slave PMIC taking turns initiating communications. This periodic structure allows one physical wire to reliably carry multiple logical functions without signal interference.
Solution Approach 2:
The control interface is designed as a universal multi-functional channel that can perform power on triggering, shutdown control, reset operations, and status monitoring all through the same single wire. The protocol layer provides the necessary function differentiation while the physical layer remains simple and unified.
Data Source
AI summary
An apparatus comprises a first printed circuit board (PCB) supporting a master subsystem including a master power management integrated circuit (PMIC) coupled to a master processor via a first local interface. The apparatus also comprises a second PCB supporting a slave subsystem including a slave PMIC coupled to a slave processor via a second local interface. The apparatus further comprises a first bi-directional control interface coupling the master processor to the master PMIC and to the slave PMIC. The first bi-directional control interface comprises at least one trace overloaded to carry multiple PMIC functions.