Medical equipment using AC power may cause leakage due to improper grounding and electrical isolation, exposing patients and medical personnel to danger, and leakage may also affect the performance of other nearby medical equipment. For medical equipment, EMC is a very important condition. From November 2005, medical equipment must comply with the updated IEC 60601-1-2: 2001 EMC standard of the International Electrotechnical Commission (IEC).
The digital data transmission part of medical equipment can isolate easily affected circuits or personnel from high-voltage environments through optocouplers or transformers. Optocoupler technology used to only support a limited data transmission rate, resulting in the widespread use of transformer isolation Application, but this method requires more circuit board space, while increasing the complexity of the design. At present, this situation has gradually changed. The good design of the photocoupler can provide effective isolation and anti-leakage effect for medical equipment.
Enhanced electrical isolation
Unlike traditional functional isolation, reinforced isolation can not only provide protection against electric shock, but also ensure the safety of the design when it fails, that is, when the system stops or fails, it can automatically keep system programs and devices in a safe state. This function For medical equipment, such as ECG electrocardiogram system (Figure 1) or shocker (Figure 2), etc., the reinforced isolation provided by the optocoupler has passed the international standard IEC / EN / DIN EN 60747-5-2 certification .
In order to meet the isolation requirements of IEC-60601-1, the photocoupler itself must have UL 1577 or IEC 60747-5-2 certification, and must also meet the requirements of the device's surface spacing, external space spacing and test voltage (mainly based on the interface insulation Depending on level). These certifications define the creepage distance as the shortest surface distance of the solid medium between the two electrically isolated conductors, and the outer space distance is the shortest distance between the two electrically isolated conductors through the atmosphere or the visible range.
When working in applications requiring enhanced isolation above 50V rms, 71V peak or DC, the insulation penetration distance (DTI, Distance Through IsolaTIon), the internal spatial spacing between conductors in isolation devices, such as in optocouplers or optoisolators The distance between the LED and the detector, see Figure 3) must be at least 0.4mm. In order to describe the typical specifications of medical equipment, Table 1 summarizes the contents of IEC 60601-1, and Table 2 is the specifications of optocouplers that meet the isolation requirements of IEC 60601, of which Type 1 requirements are only required for standard isolation requirements and work below 70V The type 2 equipment is geared toward equipment that operates at voltages higher than 70V, so it requires enhanced isolation or a similar level of protection.
In order to comply with the EMC requirements of IEC 60601-1-2 (please refer to Table 3), medical equipment must be immune to electrostatic discharge (ESD), radio frequency interference (RFI) from nearby transmitted signals and other signal sources, and power disturbances. Misoperation, in addition, the signal (conducted or radiated) emitted by the device may also interfere with other communication sources or devices that meet the specifications, so it must be kept to a minimum (refer to Table 4). The equipment must have ESD protection of 8 kV air discharge and 6 kV contact discharge, and be free from interference from 80 MHz to 2.5 GHz, as well as 3 V / m RF electromagnetic signals on non-life-supporTIng systems Interference, or 10V / m interference required by life-support system equipment, these tests are the most basic performance requirements, so there can be no device failure, programmable parameter changes, reset to factory factory predicted values, working mode changes or Error warnings and other situations occur. Properly designed optocouplers have higher EMI resistance than other isolation devices, such as transformers. The reason is that optocouplers transmit signals through the optical radiation between LED optics and photodiodes. Testing of optocouplers also shows that they can Withstand ESD voltages up to 11 kV, optocouplers can effectively deliver target differential mode signals, and shield unwanted common-mode currents and ground loop currents that cause ground voltage offsets.
In general, the optocouplers currently on the market can meet the requirements of common medical safety standards defined by IEC 60601-1. In addition, optocouplers can also provide excellent EMI without emitting electromagnetic waves, which is the current medical Important indicators of related equipment certification.
USB4 specifies tunneling of:
USB 3.2 ("Enhanced Superspeed") Tunneling
DisplayPort 1.4a -based Tunneling
PCI Express (PCIe)-based Tunneling
Main Benefits of USB 4
The new USB 4 standard has three main benefits over prior versions of USB.
40 Gbps Maximum Speed: By using two-lane cables, devices are able to operate at up to 40 Gbps, the same speed as Thunderbolt 3. The data is transmitted in two sets of four bidirectional lanes.
DisplayPort Alt Mode 2.0: USB 4 supports DisplayPort 2.0 over its alternative mode. DisplayPort 2.0 can support 8K resolution at 60 Hz with HDR10 color. DisplayPort 2.0 can use up to 80 Gbps, which is double the amount available to USB data, because it sends all the data in one direction (to the monitor) and can thus use all eight data lanes at once.
Better Resource Allocation for Video, PCIe: In lieu of alternative mode where the other interface takes over the connection, USB 4 devices can use a process called "protocol tunneling" that sends DisplayPort, PCIe and USB packets at the same time while allocating bandwidth accordingly.
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