what does the ADC "Bulb sampling mode" can do?

[Matt.Dash]

Hi, experts

May you have a nice day!

Recently, I am learning RM of STM32G474. I am a little confused about the bulb sampling function. It seems that this function cannot shorten the ADC sampling time, so what is the use of this function? hoping anyone can explain that. Thank you very much!

best wishes!

[AScha.3]

bulb ?? 8) or bulk ?

[waclawek.jan · Accepted solution]

BULB. It's somewhat surprising naming and I don't know its origin.

My reading of the RM and AN5346 is, that normally, the sampling capacitor is connected to the selected input at the moment of trigger. Then, after the set sampling time, the sampling switch opens and conversion starts.

If BULB is set, the sampling capacitor is connected to the selected input at the end of the previous conversion. After that, when trigger occurs, the the sampling switch remains to be connected to input for further time given by the sampling time setting, and after that it opens and conversion starts.

The Bulb mode timing diagram figure in RM illustrates this quite well.

In both cases, the total time during which the sampling capacitor is connected to selected input, has to be sufficient to allow proper charging of the sampling capacitor.

JW

[Matt.Dash]

thank you very much, I will study AN5346 later.

its a good explaination and I get it.