Question We are using ADUM3160 in our products where we need USB port isolation , and it is working nicely . However , so far , all our applications involved our product being the ‘device’ , i.e. it would hook up to the PC / Laptop , and then we would download data to a utility running on the PC / laptop . As is logical , we also used the +5V available from the USB port of the mater ( i.e. PC ) to power the outward side of the 3160 , thereby doing away with the need to make one more isolated +5V . Now , we are developing an application where we have my product which can be device as before , but we also support a pen drive , i.e. host mode as well . The first thing we then needed was an extra , isolated , +5V to power the other side for the pen-drive . This we have . Also , we are using a microcontroller from Microchip called PIC32 , which has on-chip USB OTG . So , all we need now is a MUX , which switches D+ and D- between the host connector and the slave connector , once every while , and on sensing one of them , holds it there till the dis-connection is sensed , and then starts toggling again . This MUX we used was MAX4717. We did this in one product , and it is working well . However , we did not need isolation in that case , as we had idolated ADE7878 signals using IL715 from NVE Corp . The schematic portion for that is attached for your reference. Now , we need to develop another product where the PIC32 has no isolation between itself and ADE7878 , and we need to hence isolate USB – both pen drive and the device connector . As I said before , I have an extra isolated 5V ready . We tried inserting two 3160s in the present working circuit which I have attached , after the MUX ( on the o/p of the MUX ) . In this case , we could get the device mode going , but not the pen-drive . My questions are : 1. Is what we did , correct ? If not , what are we doing wrong ? The device is working but the host mode is not. 2. Can you suggest a working circuit ? Answer This is the first time I have seen a customer try to implement USB OTG through separate ports. The OTG controller uses several sensing modes during the negotiations for host control that require a connection to the cable. The session request protocol will pulse the pull-up on and off, this will not pass through the USB isolator correctly. If a host negotiation protocol is initiated, the coupler cannot reverse its pull-up and pull down resistors. The ADP protocol works by sensing cable capacitance, which is blocked by the isolation. The current ADuM3160 will block the OTG protocols. I think that is why it works without the isolator, the switch will still pass the negotiation protocol signals since it is still basically connected to the controller through the switch. I would use two separate USB controllers, make one a host the other a peripheral and isolate each separately.

ADuM3160 USB speed and compatibility

Question I am currently working on a design which integrates an isolated USB-Hub. For the isolating, I am planing to use the ADuM3160BRWZ. But now I am completely confused about the USB speed and compatibility. The datasheets states the following: - USB 2.0 compatible - Low and full speed data rate: 1.5Mpbs and 12Mbps So isn't USB2.0 actually called Hi-Speed and provides 480Mps? Where am I wrong? Answer USB2.0 supports Low, Full and High speed. However you do not have to support High speed to be USB2.0 compliant. You just need to handle the request properly, on other words reject the high speed chirp with grace. Our part meets the requirements to work in USB2.0 systems, while supporting Low (1.5Mbps) and Full (12Mbps) speed data transfers. We are working on 480Mbps, but we are looking at a year out.

ADuM3160 with USB2.0 & 3.0

Question I have a device in production where I use the ADUM3160 to isolate an USB HID pheripheral. I never face any problem till now. In some PC with a USB3.0 (RENESAS USB 3.0 HOST CONTROLLER) the peripheral is not recognized (Unknown device in the Device Manager) In the same pc if I use a USB 2.0 port everything is ok. I made a test removing the ADUM3160 from the board and the PC recognize the peripheral in the USB3.0 port. I attached the schematic. Answer We have tried the ADuM3160 in USB3.0 computer ports and did not have any difficulties. The super high speed part of USB3.0 is a separate data path that does not need to be connected for the USB2.0 part to work. The only thing I might suggest is that the PIN input may be applying the pull up and trying to enumerate before the optocoupler charges up and tells the processor that it is OK to enumerate. As an experiment, try holding PIN low until the cable is plugged in then set it high and see if enumeration happens. If that works, you could use the power good signal (voltage divided down) to run the PIN and make enumeration sync up properly. Alternatively short R125 to Vdd and see if that fixes the problem. After that we would need to see the scope traces of D+/D- as the cable is plugged in. Let me know how it worked out.

ADuM3160 for USB isolation

Question I want to use the ADUM3160 to isolate a USB Line. The ADUM3160 must be connected direclty to a PC USB output, and have to drive a USB cable and the USB peripheral. What I want to know is, can I use this part also in USB1.1 environment? Is it basically possible that the part can be used on the PC side and not in the peripheral side? I read in the data sheet, that this part is designed for use in a peripheral. Regarding the +5V transmission, I will do this seperatly isolated. Answer Yes this part can be used to isolate a host like a laptop, with some limitations. The ADuM3160 only runs at a fixed speed, either low speed or full speed, set by the SPU and SPD pins. In order for a part to have full functionality as a host isolator, it has to change speed based on what gets plugged into the cable. So the ADuM3160 will work as a fixed speed host, but does not meet all of the requirements of the USB standard. Our part will be compatible with USB1.1

ADUM4160/ADUM3160: What is the difference between these 2 USB isolation devices?

Question What is the difference between the 2 USB isolation devices, ADUM4160/ADUM3160 Answer There are two differences, insulation rating and operating power supply range. ADUM3160: Insulation Rating : 2.5kV rms , power supply: 4.0 V to 5.5 V operation ADUM4160: Insulation Rating : 5kV rms , power supply: 3.0 V to 5.5 V operation

ADUM3160/4160: Can this device be used for USB-IF standard host isolation

Question

Can the ADUM4160 be used for USB-IF standard host isolation?

Answer

The ADuM4160 USB isolator is designed to isolate a peripheral port and keep the
port compatible with the USB-IF standard. It does that job very well. It was
not intended for host isolation.

That being said, because this part was intended to drop into the USB line it
has a peripheral type port and a host type port to allow it to interface with
the peripheral port of the end point device. The downstream host port is side 2
of the device and it contains the proper pull downs and drive strength to
provide host type communications. The only thing holding it back from isolating
a host is that full compliance to the USB spec requires that a host auto-detect
the speed of any peripheral plugged into it. The ADuM4160 was designed to
operate at a single speed, set by hard wiring pins SPU and SPD. So it can be
set up and will communicate as a host isolator at either low or full speed, but
it will be a fixed speed device however it is set, and so does not meet all of
the requirements of the USB-IF standard. For many customers this is adequate
for their job and they use it in this way.

So the ADUM4160 will function at either low speed or full speed USB (but only
at whichever speed has been set by hardwiring of the SPU and SPD pins. The
ADUM4160 does not support high speed USB and so it fails to pass high speed USB
signals because it blocks handshaking signals that are used to negotiate that
speed.

The circuit note CN0158 describes a circuit implementation to isolate a host
device. The hub chip chosen in this circuit note supports high speed operation,
but this mode is not allowed by the normal operation of the ADuM4160. The
upstream side of the hub controller can be thought of as a standard fixed speed
peripheral port that can be easily isolated with the ADuM4160, whereas the
speed of the downstream ports is handled by the hub controller. The hub
controller converts peripherals of different speeds to match the upstream port
speed so the hub solves the problem of adjusting the speed of the downstream
ports to match the hardwired (low or full speed) setting on the ADUM4160.

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ADUM3160/4160: Can this device be used for USB-IF standard host isolation