Author Topic: How a ucontroller has so many different packages - with great pin # disparity?  (Read 1565 times)

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Offline GiskardReventlov

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There's another post (more of a pissing contest) that mentioned MSP430 and I went over to digikey to find the data and decided to filter on DIP packages. A thought occured to me while applying the filter. How can one chip have so many different packages? I don't know what an 8-SOIC is but I do know what a 14-DIP is and I think I know what an 128-LQFP is.  Sticking to what I know, how can a chip's technology be exposed with 14-pins versus 128 pins?  I can download the datasheets but that could take me some time to sort that out and I'd guess people here know what's going on. A whole lotta bit flipping??

Just for MSP430 I see these:
8-SOIC (0.154", 3.90mm Width)
14-DIP (0.300", 7.62mm)
14-TSSOP (0.173", 4.40mm Width)
16-VQFN Exposed Pad
20-DIP (0.300", 7.62mm)
20-SOIC (0.295", 7.50mm Width)
20-TFSOP (0.173", 4.40mm Width)
20-TSSOP (0.173", 4.40mm Width)
24-TSSOP (0.173", 4.40mm Width)
24-VFQFN Exposed Pad
28-SOIC (0.295", 7.50mm Width)
28-TSSOP (0.173", 4.40mm Width)
32-VFQFN Exposed Pad
32-WFQFN Exposed Pad
38-TSSOP (0.240", 6.10mm Width)
40-VFQFN Exposed Pad
40-WFQFN Exposed Pad
48-BSSOP (0.295", 7.50mm Width)
48-VFQFN Exposed Pad
64-VFQFN Exposed Pad

Offline true

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Only certain specified pins are actually wired to the die.

The different products will use different dies - not all MSP430 is the same exact internal chip nor has the same features. But for those that use the same die, again, only certain pins are actually wired to the die.

Online Kjelt

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I know from the STM8 family from ST that a lot of their micro's with different pin layouts do use the same die. In factory they can configure how much RAM how much ROM and which pins/peripherals are active and which not. It makes also the most sense using a single die since that process is the most expensive, you build a family with the biggest specs and most peripherals, test that and then produce with some features disabled in different packages.
It is not as easy to just wire some pads and not wire others since then you could still use the other peripherals in your code/compiler/linker.
The MCU should have a unique ID which is compliant with its specs.

Now why a manufacturer makes so many packages is because there are a lot of different customers out there that want different packages. Some want a supersmall but powerfull chip for their product another want the same chip but with a lots of I/O, and very important the sales price is also very different.

Offline NANDBlog

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How can one chip have so many different packages?

MSP430 is a range of microcontrollers, kinda like PIC16 or ATMEGA. They don't even use the same silicon process, as you will find them with FRAM, ultra low power, and so on.

Offline GiskardReventlov

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I will look at the datasheets for the 14-DIP and the 128-LQFP to compare/contrast.

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