EVAL-CN0419-EBZ

Universal Serial Bus (USB) Peripheral Isolator Circuit

Overview

The CN0419 is a circuit that isolates a peripheral device that already implements a USB interface by using the ADuM4160, a USB port isolator based on Analog Devices iCoupler® technology. It is bus-powered by pairing it with a small isolated DC-to-DC converter such as the ADuM5020. The application circuit shown is typical of many medical and industrial applications.

The ADuM4160 is a USB port isolator, based on Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, these isolation components provide outstanding performance characteristics and are easily integrated with low and full speed USB-compatible peripheral devices.

The ADuM5020 is an isoPower®, integrated, isolated DC-to-DC converter. Based on the Analog Devices, Inc., iCoupler® technology, this DC-to-DC converter provides regulated, isolated power that is below CISPR22 Class B limits at full load on a 2-layer printed circuit board (PCB) with ferrites.

The EVAL-CN0419-EBZ board connects through a USB Type A Plug and is powered by the bus voltage from the USB port.

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Figure 1 CN0419 circuit block diagram

General Setup

Block assignments

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  • Terminal block P1 is the USB Male plug to be inserted to USB port

  • Terminal block P2 is the USB Female receptacle for the peripheral

  • Terminal block S1 is the switch for selection of speed operation (Full speed or Low speed)

Speed selection

Peripheral devices run at one of three speeds, low (1.5 Mbps), full (12 Mbps), and high (480 Mbps). The EVAL-CN0419-EBZ Evaluation Board can accommodate the low and full speed operations. Listed below are some examples of peripheral devices for each speed.

  1. Low speed devices

    • Examples: keyboards, mice, and game peripherals

    • Bus rate: 1.5 Mb/s

  2. Full speed devices

    • Examples: phones, audio devices, and compressed video

    • Bus rate: 12 Mb/s

The isolator is hardwired for the desired speed setting, either full speed or low speed. A switch at the upstream side allows the user to select between these speeds. To switch between the two modes, flip the actuator of S1 switch to FS mode as indicated in silkscreen for full speed operation and LS mode otherwise.

https://media.githubusercontent.com/media/analogdevicesinc/documentation/main/docs/solutions/reference-designs/eval-cn0419-ebz/ls_mode.png

Figure 2 Low speed operation

https://media.githubusercontent.com/media/analogdevicesinc/documentation/main/docs/solutions/reference-designs/eval-cn0419-ebz/fs_mode.png

Figure 3 Full speed operation

Required Equipment

  • EVAL-CN0419-EBZ Evaluation Board

  • PC with the following minimum requirements:

    • PC, Mac, Linux computer, or other host that supports USB

    • Peripheral Device (USB Flash drive, keyboard, evaluation board, etc.)

    • USB Extender (Optional)

Test Setup

https://media.githubusercontent.com/media/analogdevicesinc/documentation/main/docs/solutions/reference-designs/eval-cn0419-ebz/setup_diagram2.png

  1. Set the switch S1 to full speed or low speed operation depending on the peripheral specifications.

  2. Connect the peripheral to P2 of the EVAL-CN0419-EBZ board.

  3. Plug P1 of the EVAL-CN0419-EBZ board into the USB port of the PC/host

Running the System

  1. Make sure the setting for S1 is correct based on the peripheral device.

  2. Plug P1 of the board into the PC/host, the EVAL-CN0419-EBZ is automatically turned on and providing isolation. DS1 will light up as an indication that the board is delivering power to the peripheral device.

  3. The PC/host must recognize the peripheral connected to make sure the setup is working.

  4. Upon successful connection, you can now provide your peripheral the isolated power.