Hello
I’m building a PC Mod and I need to route some SATA 6Gbps (and maybe USB 3.0) traces through several connectors and I’m worrying about the signal integrity. Not because of the length of the traces, I think they won’t exceed 200mm, but I’m worry about the amount of connectors used.
Here you have a picture of the PC case (without the front panel)
You can see 3 stacked modules.
The upper one contains the PC motherboard and the SATA Raid card.
The 2 modules underneath contain the HDDs (2 or 3 each).
So, as you imagine I need to pass the 4-6 SATA 6Gbps connections from the upper to the 2 modules below, and therefore I wanted to use docking station like connectors.
Actually to give you all the details, that connector will carry those signals:
- 12V power to power up the HDD, and maybe the front panel, I’m not such if I will use a different power rail.
- 4-6x SATA 6Gbps
- 4-6x HDD activity signals (to connected to the front panel, well that’s another story....)
- EN signal to enable the 5V switched regulators for the HDDs (when the PC boots up)
- I2C (connected to the front panel MCU) + 3V Power
- USB 2.0 + 5V (to connect the front panel MCU to the PC)
- Maybe 2x USB 3.0 (I want to derive 2 connectors to the lowest module back panel)
The problem is the high speed buses (SATA and USB 3.0), all the other stuff is ok. How do I plan to do that? Well that way:
- The female docking connector of the first upper module is connected through SATA cables to the SATA controller card.
- On the 2nd module, 2 SATA connections are derived over a FFC connector and cable to a PCB where the HDDs are connected.
- The unused SATA connections are derived over a FFC connector and cables to the female docking connector PCB of the 2nd module to feed the 3 module.
I also planned to add SATA redrivers if needed, like the SN75LVCP601 (
datasheet) from TI to reboost the signal, at each receiver side of the links (just before the signals enter the HDD and SATA controller card), or after each connector (like drawn on the picture. Only the downstream links are displayed, actually the upstream links would have another redriver just before the signal enters the SATA RAID Card).
I wanted to use JAE WD2 Serie (
site) (
datasheet) (or similar if you know other ones!) docking connectors, that are compatible with PCIe differential signals (similar to SATA).
But they don’t mention which maximal speed is supported.
The maximal impedance is also quite high (190mOhm), the SATA requires 100mOhm +/-15%.
Well I suppose it won’t work, but
I really would appreciate opinions and suggestions of people who work with high speed buses.
Thank you!
edit:
(Sorry for my bad English
)
I have added the SATA redrivers on the picture.