Comment by artimaeis
2 years ago
It's an Intel Thunderbolt ReTimer chip.
https://youtu.be/LBWnb0ZIlEA?si=hgLg_TOa9zr42wpU&t=304
I can't find the 7040 specifically, but here's a similar 9040R chip: https://www.intel.com/content/www/us/en/products/sku/211299/...
I understand having retimer (ie. active signal booster) chips midway along a long cable... But at the end of a cable a mere 2 inches from the place the signal is going to end up seems superfluous...
Is it because the thunderbolt spec inherits timing parameters from PciE and it was hard to meet those with a long cable?
Maybe someone else can say with certainty, but I will note that they chose a > 1m cable to image. Thunderbolt 4 cables <= 1m in length can be passive, Apple's 1m cable is only $69 USD.
That probably explains the irregular pricing intervals stepping up from 1.8m $129 to 3.0m for $159. Though it's a very Apple thing to charge $30 for the extra 1.2m of cable. At least the complexity of the integrated circuit can explain that first jump.
I'd imagine both the very-high bandwidth and the PCIe interop make necessary the retimers.