The USB Type-C specification includes a blanket prohibition against these practices (However, the USB Type-C specification additionally contains intensive description on bonding the shield and the chassis, thus, I imagine that the technical committee behind USB follows a way similar to the one proposed by Henry Ott). In consequence, for a pure digital USB machine, without analog or mixed-signal circuits, and not using a metal chassis, connecting the shield directly to the circuit ground, whereas violating all of the foundations, in really a suitable compromise for many functions with justification. Thus, unless very high isolation is required, splitting the analog and digital floor planes is usually counterproductive. Using another downside in PCB design for example: In PCB design, there is a rough consensus that, if the PCB is already partitioned into digital and analog sections, the return present in every section is usually contained in their very own space. The point is that Comcast and Dish Network and all of their compatriots don't desire you utilizing your Tv, they want you using your STB. This points out the benefit of using shielded twisted pair cables at low frequency: The shield protects towards the electric field coupling and the twisted pair protects in opposition to the magnetic field coupling.
However, at high frequency, the capacitor becomes a low impedance, which converts the circuit to at least one that's grounded at each ends. Consider the case of a PCB, with an enter/output (I/O) cable, mounted inside a metallic enclosure as proven in Fig. 3-24. Because the circuit ground carries current and has a finite impedance, there will probably be a voltage drop VG across it. Within the case of a coaxial cable, the shield current will produce a noise voltage whose magnitude is equal to the shield current instances the shield resistance, as was proven in Eq. The outer shield is commonly also used to stop radiation from the cable, which outcomes from high-frequency widespread-mode currents on the cable. On the other hand, making a strong connection between the shield and the circuit ground suppresses this potential difference, reduce radiation (after all, this isn't the only potential failure mode, and that i can think about that there are different conditions that it might create the other scenario). Any small noise voltage attributable to a distinction in floor potential that may couple into the circuit (primarily at power line frequencies and its harmonics) will not affect digital circuits and may often be filtered out of rf circuits, due to the massive frequency distinction.
Many low-frequency circuits contain excessive-impedance units which can be susceptible to electric field coupling, hence, the significance of low-frequency cable shielding. Grounding the cable shield at just one end to remove power line frequency noise coupling, nonetheless, allows the cable to act as a excessive-frequency antenna and be vulnerable to rf pickup. Proper circuit grounding will cut back the radiated emissions from the product as well as increase the product’s immunity to exterior electromagnetic fields. 2.15.2.4 Double Shielded Cable Grounding. Think of a cable shield as an extension of the shielded enclosure. In the event you think of a cable shield as being an extension of the enclosure’s shield, then it becomes clear that the shield ought to be terminated to the enclosure not to the circuit ground. Two information pins plus a shield, instances 4, means 12 pins. That's most, however not all, of the 19 pins on an HDMI connector. There actually is not any video concerned in this situation, so in a way the HDMI cable is generally unused. Considering the listing of high-level features in the specification, "One Touch Play" implies that a gadget can indicate that it has video to show (causing a Tv to activate and choose that input) whereas "System Standby" implies that a gadget being turned off can inform the opposite devices on the bus to turn off as well.
Kodi flip your Tv on. This potential distinction, and therefore the shield current, is often the results of 50/60-Hz currents in the ground. Any deviation would change their applicability and outcome. Because the potential difference between the cable and chassis ought to be minimized, the connection between the PCB ground and the chassis turns into important. The supply of my declare was Tim Williams, one participant of the earlier debate within the remark section, he was already known to me as a prolific poster on the EEVblog forum, and i remember seeing his extensive writing on the subject of the USB shield connection. HDMI keeps gaining options, video video games are an enormous driver of excessive-finish Pc and tv sales, there is an inevitable convergence occurring between "monitor" and "Tv," and between "video supply" and "pc." But the pc video industry is, properly, shield control cable a bit sluggish to catch on. For instance, when the consumer selects a machine to look at on their Tv, the Tv can send a "Set Stream Path" message (opcode 0x86). The parameter on this message is the bodily CEC deal with of the desired system, and any CEC switches in the trail are anticipated to see the message and choose the appropriate enter to kind a path from the chosen system to the Tv.
>>>2024-06-02 Consumer Electronics Control (PDF)
by Doyle Omalley (2025-01-22)
The USB Type-C specification includes a blanket prohibition against these practices (However, the USB Type-C specification additionally contains intensive description on bonding the shield and the chassis, thus, I imagine that the technical committee behind USB follows a way similar to the one proposed by Henry Ott). In consequence, for a pure digital USB machine, without analog or mixed-signal circuits, and not using a metal chassis, connecting the shield directly to the circuit ground, whereas violating all of the foundations, in really a suitable compromise for many functions with justification. Thus, unless very high isolation is required, splitting the analog and digital floor planes is usually counterproductive. Using another downside in PCB design for example: In PCB design, there is a rough consensus that, if the PCB is already partitioned into digital and analog sections, the return present in every section is usually contained in their very own space. The point is that Comcast and Dish Network and all of their compatriots don't desire you utilizing your Tv, they want you using your STB. This points out the benefit of using shielded twisted pair cables at low frequency: The shield protects towards the electric field coupling and the twisted pair protects in opposition to the magnetic field coupling.
However, at high frequency, the capacitor becomes a low impedance, which converts the circuit to at least one that's grounded at each ends. Consider the case of a PCB, with an enter/output (I/O) cable, mounted inside a metallic enclosure as proven in Fig. 3-24. Because the circuit ground carries current and has a finite impedance, there will probably be a voltage drop VG across it. Within the case of a coaxial cable, the shield current will produce a noise voltage whose magnitude is equal to the shield current instances the shield resistance, as was proven in Eq. The outer shield is commonly also used to stop radiation from the cable, which outcomes from high-frequency widespread-mode currents on the cable. On the other hand, making a strong connection between the shield and the circuit ground suppresses this potential difference, reduce radiation (after all, this isn't the only potential failure mode, and that i can think about that there are different conditions that it might create the other scenario). Any small noise voltage attributable to a distinction in floor potential that may couple into the circuit (primarily at power line frequencies and its harmonics) will not affect digital circuits and may often be filtered out of rf circuits, due to the massive frequency distinction.
Many low-frequency circuits contain excessive-impedance units which can be susceptible to electric field coupling, hence, the significance of low-frequency cable shielding. Grounding the cable shield at just one end to remove power line frequency noise coupling, nonetheless, allows the cable to act as a excessive-frequency antenna and be vulnerable to rf pickup. Proper circuit grounding will cut back the radiated emissions from the product as well as increase the product’s immunity to exterior electromagnetic fields. 2.15.2.4 Double Shielded Cable Grounding. Think of a cable shield as an extension of the shielded enclosure. In the event you think of a cable shield as being an extension of the enclosure’s shield, then it becomes clear that the shield ought to be terminated to the enclosure not to the circuit ground. Two information pins plus a shield, instances 4, means 12 pins. That's most, however not all, of the 19 pins on an HDMI connector. There actually is not any video concerned in this situation, so in a way the HDMI cable is generally unused. Considering the listing of high-level features in the specification, "One Touch Play" implies that a gadget can indicate that it has video to show (causing a Tv to activate and choose that input) whereas "System Standby" implies that a gadget being turned off can inform the opposite devices on the bus to turn off as well.
Kodi flip your Tv on. This potential distinction, and therefore the shield current, is often the results of 50/60-Hz currents in the ground. Any deviation would change their applicability and outcome. Because the potential difference between the cable and chassis ought to be minimized, the connection between the PCB ground and the chassis turns into important. The supply of my declare was Tim Williams, one participant of the earlier debate within the remark section, he was already known to me as a prolific poster on the EEVblog forum, and i remember seeing his extensive writing on the subject of the USB shield connection. HDMI keeps gaining options, video video games are an enormous driver of excessive-finish Pc and tv sales, there is an inevitable convergence occurring between "monitor" and "Tv," and between "video supply" and "pc." But the pc video industry is, properly, shield control cable a bit sluggish to catch on. For instance, when the consumer selects a machine to look at on their Tv, the Tv can send a "Set Stream Path" message (opcode 0x86). The parameter on this message is the bodily CEC deal with of the desired system, and any CEC switches in the trail are anticipated to see the message and choose the appropriate enter to kind a path from the chosen system to the Tv.