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Galvanic insulated USB interface (or cable)

IP.com Disclosure Number: IPCOM000126703D
Published in the IP.com Journal: Volume 5 Issue 8A (2005-08-25)
Included in the Prior Art Database: 2005-Aug-25
Document File: 3 page(s) / 548K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

A USB (Universal Serial Bus) interface is defined as a SELV (Safety Extra Low Voltage) interface by the international safety regulation. Therefore, the interface does not offer any kind of electrical hazard for the user and can be touched during equipment installation and operation. On the other hand since no additional hardware circuits are foreseen, external PABX (Private Automatic Branche Exchange) interfaces directly connected to the equipment are considered to be of the type TNV1 (Telecommunication Network Voltage 1). Circuits of the type TNV1 offer electrical hazard to the user and cannot be touched directly during operation. As shown in figure 1, these interfaces cannot be connected directly to SELV interfaces, which could expose both the user and the SELV equipment to high voltage. A USB interface is normally attached to a microprocessor and it is necessary to implement a galvanic insulation interface between the USB interface device and/or the respective supporting microprocessor from all TNV circuits in the equipment. Since these circuits are connected via several parallel or serial ports, sometimes at very high rates, it is not economically suitable. Until now there is no solution for this problem

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Galvanic insulated USB interface (or cable)

Idea: Marcello Fogaca, BR-Curitiba

A USB (Universal Serial Bus) interface is defined as a SELV (Safety Extra Low Voltage) interface by

the international safety regulation. Therefore, the interface does not offer any kind of electrical hazard for the user and can be touched during equipment installation and operation. On the other hand since no additional hardware circuits are foreseen, external PABX (Private Automatic Branche Exchange) interfaces directly connected to the equipment are considered to be of the type TNV1 (Telecommunication Network Voltage 1). Circuits of the type TNV1 offer electrical hazard to the user and cannot be touched directly during operation. As shown in figure 1, these interfaces cannot be connected directly to SELV interfaces, which could expose both the user and the SELV equipment to high voltage. A USB interface is normally attached to a microprocessor and it is necessary to implement a galvanic insulation interface between the USB interface device and/or the respective supporting microprocessor from all TNV circuits in the equipment. Since these circuits are connected via several parallel or serial ports, sometimes at very high rates, it is not economically suitable. Until now there is no solution for this problem

This idea comprises three main parts: a device USB interface, a host USB interface and an insulating communication interface. It purposes a galvanic insulation interface which gives the ability to connect SELV equipments (personal computers, pointer devices, keyboards, digital cameras, and memory devices) to TNV1, TNV2 and TNV3 peripheral interfaces from other equipments via standard USB connection, as shown in figure 2.

Figure 3 shows the architecture of the galvanic Insulated USB interface. The Device USB Interface operates electrically as defined by the USB standard. Examples of devices supporting such kind of interface...