#Adafruit usb isolator case license

Works with any 1.5Mbps (low speed) or 12Mbps (full speed) USB device. This handy little low-cost USB isolator is exactly what you need to provide protection against harmful noise, ground loops, surges, and spikes. It might actually make sense to use a DC21 or DC25 power jack for the 5V input DC power, instead of a micro-USB connector (upper left corner of the schematic).Have some USB logic analyzer, multimeter or oscilloscope and bumping up against the frustation of a shared earth ground? The Offspring (known for being electrical engineers) wisely sang 'Ya gotta keep'em isolated!' Power and signal isolation improves common-mode voltage, enhances noise rejection, and permits two circuits to operate at different voltage levels. This is very specific to Teensy, and the use case is a bit weird, because end-users must be told to use specific USB wall warts for power supply (as opposed to, say, connecting a second USB from the computer).

#Adafruit usb isolator case license

I'm happy with any open/free license for such a design.

Also, it might be very useful to have two variants of the board, the other with just 3.3V needed - avoiding the expensive buck-boost converter, using just a 3.3V LDO regulator instead.) (I've omitted the ADuM3160 datasheet suggestions for actual capacitor, inductor, and resistor types. Since something like this is so often needed, I'm certain I'm not the only one looking at such a circuit.Ĭould you (anyone?) help with the design of such a board? If you have experience with ADuM3160, could you check if I've missed anything obvious in the schematic above? I'd prefer to cannibalize a USB-to-micro-USB cable, so that I could use the last 1' or so to connect the board to the Teensy (allowing for easy inclusion within different enclosure types), and use the rest as a built-in USB cable to the computer - thus, just through-holes for the wires, no connectors on board. My intention is to put this onto a small additional board.

Remember: the above circuit assumes the USB power is supplied by a galvanically isolated supply. Although I won't be using it, I've included the 3.3V regulator (MCP1726) in the upper right corner.Īs I mentioned, for 3.3V only operation, the TPS63061 can be left out, but then the ADuM3160 should be wired slightly differently, as indicated in the datasheet. Here, I've fixed the ADuM3160 for full-speed operation (12Mbit/s), and supply Teensy with 5V using the USB connector. I have checked the suggested/typical use circuits, and the resulting schematic looks suspiciously simple to me. In my case, Teensy will be the only one using 3.3 V, so I'm looking at using a buck-boost DC-DC regulator like Texas Instruments TPS63061 ( datasheet) that can take a DC voltage between 2.5 V and 12 V, and provide a nicely regulated 5V supply and enough current (1.4 A, if the wall-wart supplies enough current) to power the Teensy, USB isolator, and peripherals (like SN75160 and SN75162 GPIB/IEEE-488 transceivers in my case). A 3.3 VDC low drop-out voltage regulator (like Microchip MCP1726 datasheet) can be used for 3.3 V peripherals, ADuM3160 (although slightly different wiring compared to below), and the Teensy itself. To avoid the ground loop via USB ground, an USB isolator chip like Analog Devices ADuM3160 ( datasheet) can be used to galvanically isolate the Teensy from the USB bus. It occurred to me that 5 VDC regulated wall-warts are ubiquitous, and the safe ones are galvanically isolated. I do believe the audio folks encounter this often, too. In my case, the peripherals are 5 VDC (GPIB aka IEEE-488 bus transceivers to interface to oscilloscopes and such).

The computer the Teensy is connected to, and the external hardware Teensy interfaces to, are rarely using the same ground potential.

As you probably know, ground loops (ground potential differences) are a frequent headache when using a Teensy to interface to external hardware.