TUSB9261: Using TUSB9261 in M.2 SATA application

Hi Rafal,

Please accept my friend request, and I will get the linux version of the burner we have to you.

Rafal Dolny said:

what do You think is the best option to use USB_VBUS pin in that kind of storage devices? Short it to 3V3 with resistor divider?

USB_VBUS should just connect to the VBUS from the USB connector. There should be no need to divide it down.

Please keep in mind that we currently have limited support capabilities for the TUSB9261 software. We currently provide customers the firmware and software for them to adapt it to their needs, and give them a starting point.

Please let me know if you have any other questions.

Thanks,

Ryan

Hi Rafal,

Sorry, a correction to an input I had yesterday.

You must divide USB_VBUS down to a max of 1.2V using the divider specified above.

Again, sorry about the confusion.

Thanks,

Ryan

So if I want to use a M.2 SATA drive where supply voltage is +3V3 and there is no possible to unplugging devices there won't be any problem? Then only thing I have to do is to calculate divider from Vsupply to 1V2 right? In some cases I saw IC's that there was need to be plugged in to trigger connection. Technically main CPU with USB will be permanently connected to the bridge and ssd drive. I need only basic application. Later I can send here an example circuit of that what I think is necessary ok?

sheet.pdf

So, there we have M.2 connector for SSD SATA drive and TUSB9261 with SPI Flash. Is this the most simplified application? SATA_GRST# can be driven by CPU or simply pulled-up? USB is connected to main CPU.

Hi Rafal,

For USB_VBUS, this pin is typically connected directly to the VBUS of an upstream USB connection, and is used to determine whether there is a USB connection or not. For the voltage of VBUS, this is typically 5V, but can be anywhere between 4 and 10V.

Where is the 3.3V for USB_VBUS coming from? Is the voltage divider a different value than what is suggested from the pin description in order to accommodate for 3.3V?

For example applications, I would recommend looking at the TUSB9261DEMO EVM. This should give a good idea of a typical application for the TUSB9261 with USB3.0 and SATA: https://www.ti.com/tool/TUSB9261DEMO . If needed, I can reach out and provide the designs for this board.

Additionally, I will reach out with the Linux flashburner.

Please let me know if any other questions come up.

Thanks,

Ryan

I mean that the SSD drive will be inserted in M.2 slot so there won't be any 5V voltage. Maybe for something in our system I can make some 5V rails. In this situation SSD have to be always connected to USB. So If I adjust USB_VBUS to specific voltage (for example 5V) and permanently connect it to that voltage (because there won't be any option to insert or remove that disk when system is power on) it will work fine? I calculated resistor values from https://www.ti.com/lit/ug/sllu139a/sllu139a.pdf?ts=1707482218530&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTUSB9261. On page 18 there is a schematic where VBUS pin is connected to USB port so 5V is divided with 91k and 10k resistors to something around 0V5. I want to make power switches to shorting 3V3 rail for M.2 and I hope it can generate this same voltage on USB_VBUS pin when 3V3 is achieved on SSD supply.

Hi Rafal,

Could you send a block diagram for your intended application with this? Typically, the 5V will come from the upstream USB connection, and not the SSD connection. Do you just want the device to always believe that it is connected to an upstream USB host, regardless of whether it is or not? I believe this application may be risky, as the detection of VBUS is used to signal when the device should try to connect to the USB at SuperSpeed.

Ideally, 4-10V is used for the USB_VBUS voltage divider.

Please let me know on those questions.

Thanks,

Ryan

My apologize, I had to work on other things. So I am back. As You see I have only 3V3 and maybe some other voltages generated for specific IC's like 1V8 for some GPIO's from SMARC 2.0 and 1V1 for TUSB9261. In that module I have some USB modules but that I need to use don't have VBUS_DET, only other pin is EN_OC#. This is bidirectional pin for something like here (power switch with overcurrent fault#). So I think the best option is to connect with divider +3V3_SSD to USB_VBUS in TUSB9261. What do You think?