Hi, our product is one set of transmitter/receivier based on nRF24 series. Recently, the number of failures of receivers increases quickly, and most of failures are shown as:
1. "Unknown Device" in Windows OS;
2. Part of flash bits turning over from 1 to 0 (flash address: 0x2015 - 0x205F, or 0x3600 - 0x3610).
Both kinds of failures can be solved by only re-download FW.
The receiver part is based on nRF24LU1P whose document is too few, only Product Specification V1.1 is available actually.
We plan to review our schematic & layout design and make some optimization, but information related to hardware design in PS V1.1 does not include filters and protection circuits of USB power and signal.
Could any one give me some more reference schematic & layout designs, especially about USB power & signal please, so that we can review our design further and solve relative problems? Thanks a lot!
Moreover, there are VDD traces on the TOP layer right under the chip in the reference layout , where an exposed pad actually exists. It is also recommended in PS V1.1 Chapter 24 that exposed pad should be kept unconnected. What is the influence if the exposed pad is connected to ground directly?
What's more, does any one have experiences about flash bits' turning over, not only based on nRF24 series? Knowing that our products are used in industrial automatic, where no high-energy radiation ever exists.
