# STM32L471 -ADC clock frequency(fADC)=80 MHz, Sampling rate for FAST channels(fs)=5.33Msps for 12bit

#### mishra87

Joined Jan 17, 2016
985
Hello all,

I have confusion in ADC of STM32L471 datasheet parameters.

2. Sampling rate for FAST channels(fs)=5.33Msps for 12bit --------what is this and where is its application in ADC
3. External input impedance (RAIN)=50Kohm--------what is this and where is its application in ADC
4. Internal sample and hold resistor(RADC) = ?? what is this and how to decide its value
5. Internal sample and hold capacitor(CADC) =5pF --------what is this and how to decide its value
6. Sampling time(ts)= 8.00625 µs --------what is this and how to decide its value
7. Total conversion time(tCONV)= 8.1625 what is this and how is its calculated

#### OBW0549

Joined Mar 2, 2015
3,566
If you're confused about the meaning of those terms you need to back away from the STM32L471 and start your learning with a much, MUCH simpler microcontroller-- and do a lot of reading and studying about ADCs in general. To anyone familiar with microcontrollers and their ADCs, each and every one of those terms is self-explanatory. If they're a mystery to you, you are NOT yet ready to deal with a device as complex at the STM32L471.

Otherwise, read Section 16 of the STM32L471 Reference Manual, which explains everything.

#### mishra87

Joined Jan 17, 2016
985
If you're confused about the meaning of those terms you need to back away from the STM32L471 and start your learning with a much, MUCH simpler microcontroller-- and do a lot of reading and studying about ADCs in general. To anyone familiar with microcontrollers and their ADCs, each and every one of those terms is self-explanatory. If they're a mystery to you, you are NOT yet ready to deal with a device as complex at the STM32L471.

Otherwise, read Section 16 of the STM32L471 Reference Manual, which explains everything.
Senior member of this group really showing the way to young engineer !!!
Thanks !!!

#### MrChips

Joined Oct 2, 2009
28,151
Senior member of this group really showing the way to young engineer !!!
Thanks !!!
Sounds like sarcasm.

One of the things every engineer needs to learn to do is read the Reference Manual and Datasheet.

The other thing every engineer needs to learn to do is how to communicate effectively.

#### mishra87

Joined Jan 17, 2016
985
Sounds like sarcasm.

One of the things every engineer needs to learn to do is read the Reference Manual and Datasheet.

The other thing every engineer needs to learn to do is how to communicate effectively.
Its not like to sarcasm !!!
After giving 1st attempt and then reattempt again usually people ask their doubts in the forum.

Thanks !!!

#### OBW0549

Joined Mar 2, 2015
3,566
One of the things every engineer needs to learn to do is read the Reference Manual and Datasheet.
And the Application Notes...

Otherwise, read Section 16 of the STM32L471 Reference Manual, which explains everything.
@mishra87: Here's some additional info. Most PIC microcontrollers include an on-chip A/D converter, and Microchip have provided several app notes discussing these ADCs, how they work and how to use them. The two I've attached go into some detail on the questions you asked and may help to clarify things.

#### Attachments

• 236.5 KB Views: 3
• 205.7 KB Views: 2