About MAX10 IO pin pull-up

[Yamada1]

It would be helpful if you could tell me about the pull-up of the IO pin of MAX10.

1) In the UG-M10PWR, it is stated that the tri-state and weak pull-up resistors are enabled during power-up due to the POR circuit, but is this also the case during the power-down sequence?

2) If the power is completely turned off, will the weak pull-up resistor on the I/O pin not work? (In other words, will the I/O pin be floating?)

We apologize for the inconvenience and appreciate your understanding.

[AqidAyman_Intel]

1.  Based on the Max 10 Handbook, the output buffers of the Intel MAX 10 device are turned off during system power-up or power-down. The Intel MAX 10 device family does not drive out until the device is configured and working in the recommended operating conditions. The I/O pins are tri-stated during power up or power down. The internal weak pull-up resistors are disabled by default during power up. You need to enable the internal weak pull-up resistors through the Intel Quartus Prime software.
2. The weak pull-up resistor in Intel MAX 10 device I/O elements (IOE) keep the I/O pins from floating. Before or during power down, you can drive signals into I/O pins, dedicated input pins, and dedicated clock pins without damaging the Intel MAX 10 devices.

[Yamada1]

Thank you for answering.

Thank you for explaining the details. Is it okay to understand the following?

1) Weak pull-up is disabled by default, but can be enabled through settings from the Quartus Prime software.

2) When weak pull-up is enabled, it prevents I/O pins from floating during power-up and power-down.

3) I/O pins are floating when the power is completely off.

Also, I apologize for the repeated questions, but I would appreciate it if you could explain the following points.

4) If weak pull-up is enabled, are the I/O pins floating from power-on until POR operates? Or will the weak pull-up be enabled from the moment the power is turned on, and the power supply voltage will be visible during power-up?

We apologize for the inconvenience and appreciate your understanding.

[FvM]

Hi,
my reading of MAX10 device handbook gives a slightly different picture. There are basically three different states:
1. Supply voltage below POR threshold
According to Fig. 2.7 and related description, weak pull-up is unconditionally enabled, drivers are disabled.
2. Configuration mode
State of weak pull-up is controlled by ICB, default is enabled. See Table 2.5.
3. User mode
Weak pull-up is controlled by general and pin specific configuration.

Regarding state during power down and missing supply. If power down triggers POR comparator, same situation as power up. Zero supply - not specified. Depends on Vgs,th of pull-up transistor, the question sounds somewhat sophistic to me.

[Yamada1]

Thank you for your comment.

In the answer from AqidAyman_Intel, it was said that weak pull-up is disabled by default.

Since it was a machine translation, there was a possibility of a mistranslation, so I checked to see if it was recognized.

Also, I'm sorry for the lack of words.

What I wanted to check in question 4) was whether the I/O pins are floating when the power is off, or whether they are connected to weak pull-ups.

This is because the device connected to the I/O of the circuit under investigation starts up first, and I wanted to know the state of the MAX10's I/O pins when the power is turned off.

We apologize for the inconvenience, but it would be helpful if you could teach us.

[FvM]

I can confirm that MAX10 pins are high impedance (> 10 Mohm) with 0 V supply.

[AqidAyman_Intel]

Hello Yamada,

I wish to follow up with you.

Is there any more support needed on your question?

Regards,

Aqid