Communication Interface Buffer Hot-Swap Protection for Bus Signal Integrity
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Solution Overview
Problem
Conventional approaches to hot-swapping PCB cards require costly contact length variance and specialty connectors to prevent data corruption, which increase the expense of both the PCB cards and related devices or systems.
Innovation Solution
A communication interface buffer with a bus signal driver circuit that maintains high impedance during hot-swap events, preventing existing signals on the system bus from being corrupted by turning off the output transistor until a stable supply voltage is available, thus eliminating the need for staggered contacts and specialty connectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact length variance and specialty connectors are used to prevent data corruption during hot-swap, then data integrity is improved, but device cost increases
Solution Approach 1:
The patent changes the electrical parameter (impedance) of the communication interface buffer dynamically. By switching from a low-impedance driving state to a high-impedance floating state during hot-swap events, the buffer prevents voltage level corruption without requiring special mechanical connector designs or varied contact lengths.
Solution Approach 2:
The patent detects the hot-swap event in advance (when the PCB card is being inserted or removed) and proactively switches the buffer to high-impedance mode before data corruption can occur. This preliminary protective action prevents the harmful effect rather than correcting it afterward, eliminating the need for expensive preventive mechanical designs.
2Reliability
If contact length variance is implemented to protect against hot-swap corruption, then signaling quality is improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces the mechanical solution (varying contact lengths in connectors) with an electronic solution (impedance control via buffer switching). Instead of designing complex mechanical connector structures with different contact lengths, the patent uses an electronic buffer that can dynamically change its electrical state to protect against hot-swap events.
3Reliability
If specialty connectors are used to prevent data corruption during hot-swap, then data integrity is improved, but system expense increases
Solution Approach 1:
The patent uses a simple, inexpensive buffer circuit that can be easily integrated into standard PCB designs. This inexpensive electronic protective measure replaces expensive specialty connectors, making hot-swap protection affordable for standard manufacturing processes without requiring specialized or proprietary connector designs.
Data Source
AI summary
A communication interface buffer comprises: a data bus connection adapted to be coupled to a bus interface contact; and a ground. The communication interface buffer also comprises an output transistor with a first current terminal, a second current terminal and a control terminal, the first current terminal coupled to the data bus connection, the second current terminal coupled to ground, and the control terminal adapted to receive a drive signal. The communication interface buffer also comprises a control circuit coupled to the control terminal of the output transistor, wherein the control circuit is configured to: turn off the output transistor during a first interval that starts when the data bus connection is coupled to the bus interface contact; and turn on the output transistor after the first interval is complete.