Hello experts,
I have a question about the part shown in the figure below.
My customer connects the Enable and nSCS pins to a 3.3V processor. In the figure below, the ENALE pin and nSCS pin are connected to 5V (DVDD). 5V seems to lead to 3.3V, is this not a problem?
Could you please tell me what kind of circuit is inside the red square and why the 3,3V processor actually works without problems?
Thank you for your help.
Best Regards,
Taito Takemura
Hi Kehr,
Thank you for your answer.
Could you please comment if my understanding below is correct?
(1) I think the internal circuit is like the figure below. Is it correct? I would like you to tell me the pull-down resistor.
(2) I think that the reason why 5V of DVDD does not adversely affect the 3.3V processor is that the voltage drops from 5V to 3.3V via the current source and internal resistance (46.5kOhm). Is it correct?
Best Regards,
Taito Takemura
Takemura-san,
ENABLE pin has the following simplified diagram. So, in additional to what you have drawn, it has a 200k pull-down.
nSCS does NOT have an internal pull-down. It looks like this:
So, your drawings above are actually flipped.
The internal resistance limits the current, so it will not cause damage to external MCU.
Regards,
Ryan
