Isolated USB Repeater – USB2.0

The project presented here is a USB port-powered, USB 2.0 isolator that isolates the USB host and USB device. It is a galvanically-isolated USB2.0 repeater, that supports low speed 1.5Mbps, and full speed 12Mbps communication. The project automatically connects and detects the bus speed. This USB 2.0 isolator is efficiently powered from the USB port and requires no external power, on board isolated DC-DC converter U1 provides 5V to the other side of the circuitry and USB port. U2 LDO provides 3.3V to the chip. L1 and L2 ferrite beads take care of noise immunity on the DC bus. The project protects the host USB port from noise and high voltage.

Features

• Compliant to USB 2.0
• Supports low speed (1.5 Mbps) and full speed (12 Mbps) signaling
• Automatic speed and connection detection
• Supports L1 (sleep) and L2 (suspend) low-power states
• Supports automatic role reversal for USB On-The-Go (OTG) and Type-C® Dual Role Port (DRP) designs
• VBUS voltage range: 4.25 V to 5.5 V (Power Supply from USB Port)
• Meets CISPR32 class B emissions limits
• Ambient temperature range: –40°C to +125°C
• Safety-related certifications:
• 7071-VPK VIOTM and 2121-VPK VIORM (Reinforced) per DIN EN IEC 60747-17 (VDE 0884-17)
• 5000-VRMS isolation for 1 minute per UL 1577
• IEC 62368-1, IEC 60601-1 and IEC 61010-1 certifications
• CQC, TUV, and CSA certifications
• PCB Dimensions 44.77 x 25.72 mm

Features of DC-DC Converter

• Continuous short-circuit protection
• Input 5V DC
• Output 5V DC
• Maximum Load Current 400mA
• No-load input current as low as 8mA
• Operating ambient temperature range: -40℃to +105℃
• High efficiency up to 86%
• High power density
• I/O isolation test voltage1.5kVDC

The ISOUSB111 is a galvanically-isolated USB 2.0 compliant repeater supporting low speed (1.5 Mbps) and full speed (12 Mbps) signaling rates. The device supports automatic connect and speed detection, reflection of pull-ups/pull-downs, and link power management allowing drop-in USB hub, host, peripheral, and cable isolation. The device also supports automatic role reversal – if after disconnect, a new connect is detected on the Upstream facing port, then the Upstream and Downstream port definitions are reversed. This feature enables the device to support USB On-The-Go (OTG) and Type-C Dual Role Port (DRP) implementations. This device uses a silicon dioxide (SiO2) insulation barrier with a withstand voltage of up to 5000 VRMS and a working voltage of 1500 VRMS. Used in conjunction with isolated power supplies, the device protects against high voltage and prevents noise currents from the bus from entering the local ground. The ISOUSB111 device is available for reinforced isolation. It supports a wide ambient temperature range of –40°C to +125°C.

Schematic

Parts List

Connections

Gerber View

Photos

Video

ISOUSB111 Datasheet

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