Which is the Smallest processor that has Double Precision Floating Point ?

[T J]

..

[TDK]

Probably the STM32H7A/H7B WLCSP132 chips. (4.57 X 4.37 mm)

[T J]

still 10x10mm, was hoping to get a smaller package.

the L412 QFN-48 is 5x5 but only single precision..

[Tesla DeLorean]

The F767 has the FPU-D

https://www.st.com/resource/en/datasheet/stm32f767zi.pdf

Most of these ICs have a lot of FLASH/RAM that contribute to the die size, the FPU-D is perhaps 3x size of FPU-S, I couldn't get the ARM guys to share specific info.

LQFP100 H730AB

https://www.st.com/resource/en/datasheet/stm32h730ab.pdf

https://www.st.com/content/ccc/resource/sales_and_marketing/presentation/product_presentation/group0/cf/c2/fb/68/b5/11/48/52/Microcontrollers_STM32H7_Series_product_overview/files/Microcontrollers_STM32H7_Series_product_overview.pdf/jcr:content/translations/en.Microcontrollers_STM32H7_Series_product_overview.pdf

[Danish1]

One thing the OP didn't make clear was whether it is acceptable to do the floating-point in software.

All the compilers provide software double-precision floating-point where it's needed. It will increase execution-time (hence power-consumption), and use up more FLASH. But often this is a good overall solution.

But even the smallest stm32l0 can do it. A quick check found stm32l052T8 is 2.61 x 2.88 mm but I don't know if that's the smallest.

[T J]

Yes, we need to shutdown quick, so hardware is the best answer.
In the end, I Had to compromise, with the L433-48pin, will have to calculate the double from the Single Floating Point Hardware.