STM32H743 ADC Conversion/Sampling time

[deckhard]

Hi,

I wonder if the STM32H743 can sample and convert 1 ADC sample in 10 nanoseconds?

According to the specs the ADC speed (sample + convert) at 14bit resolution with 50MHz ADC clock , one sample will take 200 nanoseconds.

I have no problem lowering the resolution to 8bit.

How much time will it take, considering the same ADC clock speed?

[TDK]

10ns corresponds to a frequency of 100 MHz. The ADC clock is 50MHz max. So no, it can't sample and convert in under one ADC clock.

[deckhard]

Do you know of any other ST device that could achieve that?

BTW how do you work out the math?

Thanks!

[TDK]

> Do you know of any other ST device that could achieve that?

100 Msps is incredibly fast. You're going to need a specialized ADC chip and an FPGA to handle the data. It's not something you're going to find in a microcontroller.

> BTW how do you work out the math?

1 / (10 ns) = 100MHz

Not sure how else to explain that.

[deckhard]

Right so 50Mhz would correspond to 20 nanoseconds. So why does the specification indicates it takes 200 nanoseconds? Because each sample takes 10 clock cycles?

[deckhard]

Is it possible to use the STM32H7 gpio pins as parallel bit bus for this propose?

For example is I connect 8 gpio pins (+clock) (for 8 bit resolution) to an external A2D, would it be possible to reach the time of 10 nanoseconds per sample?