Why faster MCU's always get's large pin packages!

[MT]

Why does faster MCU's always get bigger pin packages (more peripherals argument exluded) and not smaller?
Why cant i buy a 1Ghz/32bit MCU in SO16?

[rstofer]

Count the number of pins used for power.  On the faster devices, I would expect to see more pins used for the various voltages.  As well, speed causes heat and the package has to get the heat out.

[wraper]

Why cant i buy a 1Ghz/32bit MCU in SO16?

Silicon die probably won't fit in the package. And what's the point in such MCU, what are you going to do with it with given pin count limitation that would require 1Ghz/32bit?
EDIT: that said without mentioning other issues like power delivery/decoupling. Also 1GHZ is not even in MCU league at all. Those SoC chips normally have external RAM and flash, often as second BGA package on top of them.

[coppice]

Do you have some high volume applications for a 1GHz MCU with very very few I/O pins? If you do, I'm sure you'll inspire some MCU maker to produce you a part in a fairly low pin count package. It probably won't be 16 pin, as they and unlikely to achieve good signal integrity with so few power pins, but they could probably do a nice small 30-40 pin BGA for you.

[brucehoult]

The 320 MHz FE310-G000 RISC-V is in a QFN48 package.  Any advance on that?

Yes, it would be nice. Sometimes you want compute more than huge I/O.

[brucehoult]

The 320 MHz FE310-G000 RISC-V is in a QFN48 package.  Any advance on that?

Yes, it would be nice. Sometimes you want compute more than huge I/O.

I found some lowish pin count chips.

64 pins 300 MHz ATSAMS70J19A-AN ATSAME70J21A-AN and friends (ARM)

64 pins 500 Mhz 8 core (!) XL208-128-TQ64-C10 XLF208-128-TQ64-C10 XU208-128-TQ64-C10 XUF208-128-TQ64-C10
48 pins 500 MHz 6 core XS1-L6A-64-TQ48-C5 (and 400 MHz 4 core XS1-L4A-64-TQ48-C4)

In fact these latter chips share the available 400 or 500 MIPS of a single core between up to 8 hardware threads, with a maximum of 100 MIPS for each thread

[NorthGuy]

You certainly can pack lot more than 16 pins into a package of the same size as SOIC 16. People who're after small size will never use SOIC.

[coppice]

You will find a number of 50-500MHz devices in fairly small packages, targeted at control applications. Many control applications only need a handful of signals, so 30 or 40 pins is quite a lot for these devices. They tend to top out at around 500MHz, though. If the device is reasonable efficient, current high volume control applications rarely need faster processing than that.

[Mechatrommer]

Why cant i buy a 1Ghz/32bit MCU in SO16?

And what's the point in such MCU, what are you going to do with it with given pin count limitation that would require 1Ghz/32bit?

on top of my head... simple hobbiest level UAV, that only control few servos, motors and sens few sensor, 3 axis gyro maybe, but inside the cpu is doing complex/matrix/floating robust adaptive control algorithm... having 64 pins cpu on board with only 16 pins used is feel like blasphemy..

[Jeroen3]

You certainly can pack lot more than 16 pins into a package of the same size as SOIC 16. People who're after small size will never use SOIC.

Exactly. You can get 80 MHz Cortex M4F in 3x3mm WLCSP49 (wafer level chip scale package).
It's an minuscule package, literally the chip flipped over with solder balls directly on an extra metal layer.

[MT]

I assumed you would see the "figuratively" metaphorically speaking , so keyword are still "small pin count+ very high speed", whether it's SO16, SSOP10 TQFP20,WLCSP10, etc, etc.

OK  so why cant i buy a SSOP10/WLCSP10/TQFP25 1Ghz 32 bitter?

[MT]

Why cant i buy a 1Ghz/32bit MCU in SO16?

And what's the point in such MCU, what are you going to do with it with given pin count limitation that would require 1Ghz/32bit?
EDIT: that said without mentioning other issues like power delivery/decoupling. Also 1GHZ is not even in MCU league at all. Those SoC chips normally have external RAM and flash, often as second BGA package on top of them.

Sometimes, actually many times you want to compute a lot on a very tiny space, audio one among many apps, serial in serial out on TDM. Other things could be distributed computing instead of one big fat complicated expensive PCB one uses many simple PCB. The argument that just because a MCU is fast it need many pins is inadequate.

Example situation: A mixed signal board, many timers, many uarts, many ADC channels etc, all runs in low power mode slow speed, CPU runs at say 27Mhz all mounted on "single side" (like swear in church) ultra low china cost PCB.

Now you need big fat powerful computing! What do you do? Slabbing on current market solutions is going to ruin the
whole solution so if there was a 1Ghz 32 bit SO8/WLCSP10 MCU (1.34euro) with a serial com's for offload that would be splendid you dont agree? Easier to say no instead?

[mdszy]

I assumed you would see the "figuratively" metaphorically speaking , so keyword are still "small pin count+ very high speed", whether it's SO16, SSOP10 TQFP20,WLCSP10, etc, etc.

OK  so why cant i buy a SSOP10/WLCSP10/TQFP25 1Ghz 32 bitter?

I think it's already been made clear that 1GHz is pretty unreasonable for a MCU.

[coppice]

I assumed you would see the "figuratively" metaphorically speaking , so keyword are still "small pin count+ very high speed", whether it's SO16, SSOP10 TQFP20,WLCSP10, etc, etc.

OK  so why cant i buy a SSOP10/WLCSP10/TQFP25 1Ghz 32 bitter?

I think it's already been made clear that 1GHz is pretty unreasonable for a MCU.

Its not unreasonable. Its just the market which is questionable. If there is a demand you could make a nice 1GHz MCU, running entirely from RAM, booted from a very cheap serial flash chip.

[NorthGuy]

Now you need big fat powerful computing! What do you do? Slabbing on current market solutions is going to ruin the
whole solution so if there was a 1Ghz 32 bit SO8/WLCSP10 MCU (1.34euro) with a serial com's for offload that would be splendid you dont agree? Easier to say no instead?

Of course, it would be wonderful if you could get nearly infinite amount of computing power in a very small package which would consume few nA when it runs at full speed and would cost $0.06. But until such things get available, you need to compromise.

Either you get a big fat processor which is big (plus lots of other stuff that it requires on PCB), consumes lots of power and costs a lot, but runs fast and gives you lots of resources to waste.

Or, you use very small low power MCU which costs little, but doesn't have any resources to waste. So, you need to apply your time and your brain to make it work.

Or anything in between.

The choice is always yours.

[MT]

If there was a choice of a 1Ghz/32 bit in a xxxxx package i guarantee that you would in less then 5 secs orders 3 samples of it! So there are no "real" choice's, only expensive ""forced-upon-you" solutions. Why are mobile phones small and dont incorporate "your big and fat" solution?

So, the "fastest+smallest" and easy to get dev software solution as of today is XS1-L4A-64-TQ48-C4.

[NorthGuy]

Why are mobile phones small and dont incorporate "your big and fat" solution?

They're not small by any means. You wouldn't have any problems finding a very fast CPU which would fit into a phone form factor. Small CPUs are much smaller than that - you can fit a dozen on a penny.

[CM800]

So.... what do you need it for? Can't really come up with many applications that are high enough volume for it to be worth while.

If it's that valuable, you could buy a wafer-level package and make your own tiny SoC for the application.

[mdszy]

If there was a choice of a 1Ghz/32 bit in a xxxxx package i guarantee that you would in less then 5 secs orders 3 samples of it! So there are no "real" choice's, only expensive ""forced-upon-you" solutions. Why are mobile phones small and dont incorporate "your big and fat" solution?

Mobile phones are using full-fledged SOCs that are optimized for size. The entire chipset is in a single package, so there don't need to be as many pins exposed to the PCB itself since lots of the connections are between dies in the same package.

[mikerj]

on top of my head... simple hobbiest level UAV, that only control few servos, motors and sens few sensor, 3 axis gyro maybe, but inside the cpu is doing complex/matrix/floating robust adaptive control algorithm... having 64 pins cpu on board with only 16 pins used is feel like blasphemy..

A Cortex M4 based micro is already powerful enough to run a flight controller for such a vehicle.

[colorado.rob]

A Cortex M4 based micro is already powerful enough to run a flight controller for such a vehicle.

It depends on how complex you flight controller will be.  But if you're using vision systems, lidar, or other fancy inputs, you need more pins anyway.  So, yeah... what @miker said.

The thing is, there is never the "perfect part".  Engineering is the art of compromise and trade-offs.  What's the cheapest thing that meets your needs?  The only reason a bigger pin package is a problem is the board space it takes up for TQFP or the number of layers and PCB cost associated with BGA.  But with a BGA, if you only need a few of the pins, routing becomes easy and PCB cost comes down.

[westfw]

Silicon die probably won't fit in the package.

Indeed.  A 1GHz cpu depends on a lot of logical structures - L1 cache, L2 cache, instruction pipelines, branch prediction units, and so on,  that are "very large" wrt the die area they occupy.  And then they eat a lot of data, so they need a lot of memory, which means more die area for either on-chip memory or memory controllers.

The limiting factor for a lot of the faster microcontrollers seems to be flash memory access speed, rather than cpu clock speed...

[fcb]

If there was a choice of a 1Ghz/32 bit in a xxxxx package i guarantee that you would in less then 5 secs orders 3 samples of it! So there are no "real" choice's, only expensive ""forced-upon-you" solutions. Why are mobile phones small and dont incorporate "your big and fat" solution?

So, the "fastest+smallest" and easy to get dev software solution as of today is XS1-L4A-64-TQ48-C4.

No point getting upset.  It's the simply the market, if there was a ready market for the size/pin count you want then i'm sure (bounded by the laws of physics etc..) that someone would be making it. Most IC's these days are designed for a lead customer (automotive/consumer/perhaps industrial sometimes).

[coppice]

Silicon die probably won't fit in the package.

Indeed.  A 1GHz cpu depends on a lot of logical structures - L1 cache, L2 cache, instruction pipelines, branch prediction units, and so on,  that are "very large" wrt the die area they occupy.  And then they eat a lot of data, so they need a lot of memory, which means more die area for either on-chip memory or memory controllers.

A 1GHz part is going to be made in a fine geometry. You can get a lot of logic on a small die at 45nm. A single core and, say, 512k of RAM isn't that big. Usually, for MCU type designs, you end up with a pad limited die. If the I/O requirements are very limited the pad ring won't be an issue, and you can make something very small.

The limiting factor for a lot of the faster microcontrollers seems to be flash memory access speed, rather than cpu clock speed...

Flash is really slow. Even with some caching and pipelining it still becomes a major speed handicap. A 1GHz device would likely boot from a small serial flash chip, and run from RAM. Even some MCUs running below 100MHz are doing this.

[KL27x]

If someone offered such a chip, even if it saved space on the pcb (which if you can operate with just the internal RAM, let's assume for sake of argument that it can be significant)... what makes you think this chip would be cheaper?