[govg]

Could you mention where these chips from older mature nodes are used and what they look like(in terms of form factor / development environment), for context? I understand some aspects of chips being used for automobiles , but aren't most compute oriented chips based off ARM designs and such which will be on the newer nodes?

[addaon]

Most of the chips I interact with on a daily basis are 45 nm, some are 28 nm. Currently working automotive, same in aerospace. A lot of this is because embedded flash generally trails several years behind general availability of a node; so if you're designing a µC or similar with embedded flash, you're starting a few years behind; and then you're guaranteeing a 10 or 15 year supply chain, so on average a production part is on a ~10 year old node (but development activities are biased towards the front of this, since you often need 7 years of remaining supply chain guarantees after start of production). Another factor is that it simply takes time to validate nodes. Automotive nodes trail general use nodes; SEU data takes a few years to gather. Even for non-embedded-flash parts, this can cause a similar delay.

As an example, the TI Hercules is an old but by no means obsolete safety processor. It's one of the best ways to get single-core lockstep capabilities for new designs today. The original TMS570LS parts are still built on a 130 nm process, but the "newer" (not new, but also newest) TMS570LC parts are on 65 nm.

These days most of my work hours are focused on the Aurix TC3xx, which is a 40 nm (tweaked 45 nm) part. This is a multi-core safety processor with an obviously higher transistor count than the Hercules (which is why it was selected for application), matching its smaller process.

Similarly in FPGA land, the Lattice MachXO is on an 130 nm process, while the newer MachXO2 migrated to 65 nm. I know Lattice does newer parts on 28 nm (and I'm sure there's 45 nm out there), but I haven't run into them.

Certainly for more density-heavy applications newer processes (28 nm, often) have come to the forefront, and we're at the point that we're seeing cost cuts going from 90 nm to 28 nm for equivalent functionality. But a lot of these designs are pin-out limited (the silicon area is dominated by getting signals on and off chip, not by the total area of transistors), so cost very much doesn't scale with transistor density; the cost per transistor has gone down, but the cost per unit area has gone up.

[kurthr]

Embedded Sensing, Most Automotive, DisplayDrivers are usually mixed signal solutions that don't benefit from process shrinks as much as others. For a long time costs continued falling on legacy (55/90/180) processes, but that has stopped and during Pandemic, and prices shot way up. Some of it is transistor noise scaling (for ADCs/DACs), some is lack of Embedded Flash (as mentioned, though TSMC is now sampling at 28nm), and some die are already so small they're pad limited. In any case a process shrink has significant design costs (and testing/requalification) so if you're not going to make it up with reduced prices (customer) and higher margins (supplier) it's unlikely to happen.

One thing that is driving new development is the lack of 8in capacity and the move to 12in (300mm) due to equipment availability. Most of the installed capacity of 80nm and larger was 8in and you can only really build new 12in fabs.

[dragontamer]

Microchip just launched the SAM9X60 like three years ago.

600Mhz and 128MB of DDR2 RAM is plenty for many applications. It's pretty much the lowest end processor you can get that will still run a Web server / GUI for easy network dongle. Even if it's on an ancient ARMv5 it still gets the job done today.

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Car and automotive is even lower end in practice. Every button is a uC whose only job is to convert button clicks into LINbus or CAN bus commands for the central computer.

No reason to go below 180nm for a lot of these chips... Well aside from cost. The older 90nm or 180nm nodes are IIRC getting more expensive as the old wafers are drying up (200mm vs modern 300mm).

A lot of cost optimized chips are 40nm to my knowledge, and others are 28nm now. TIs MSPM0 line comes to mind.

[nwellinghoff]

Radio chips used in iot devices. Bluetooth, wifi, zwave, zigbee etc. usually rely on the lager node size. Designs are produced and sometimes supported for decades.