ADC STM32H743

[mswart]

We use a STM32H743 and I want to connect an external reference voltage to the Vref pins. We use 3 ADCs, and for each ADC, we sample 4 channels. Each channel must be read at 100 ksample/s. The 3 ADCs operate continuously. A common ADC clock of 10 MHz clock is used. The resolution used is 16 bits for each channel. I have the following questions:

1) What is the average current drawn from the Vref pin for all 3 ADCs during conversion?

2) What is the Radc value?

3) The SAR ADC has internal capacitors that are charged/discharged from/to a reference voltage in a very short time during successive approximations. The voltage reference including an external buffer capacitor on the Vref pin must be capable to deliver energy in a short time without changing the Vref voltage. I read that there are buffered and unbuffered voltage references. I'm intended to use a REF3433 and an external capacitor of 10uF. The REF3433 is an unbuffered reference source. Is this type recommended for the STM32H743. Please can you clarify why or why not?

[mƎALLEm · Accepted solution]

Hello,

Next time, better to ask a question per thread. 

1)  Information that I've got from our data base:

     I REF = 80 uA for Rev V and 160uA for rev Y
     For dynamic consumption it is about 16mA/1ns (design simulation data)

2)  As stated in this thread, we don't provide Radc in the datasheet , but instead we define the Rain values for each minimum sample rate and resolution.

If you need more details and especially for question 3 you need to contact your local FAE or open an online support ticket on this link.

Hope that helps.