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Non Volatile RAM (F-RAM & NVSRAM) Forum Discussions

Tomhe85
Level 1
Level 1
First reply posted First question asked Welcome!

Dear Infineon Team,
could you please assist me with the issue below?
I could't find any clarifying information in the FM24W256 datasheet nor on https://community.infineon.com.
As I can see, the address pins (A0, A1, A2) are internally pulled-down. But my question is, may I connect these pins directly to Vdd (5V)?
On the CY8CKIT-040 evaluation board there are 0ohm pull-up resistors. On the other hand, on the CY15FRAMKIT-001 evaluation board there are 4.7kohm pull-up resistors.

Thank you for support.

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1 Solution
ritwicksharma
Moderator
Moderator
Moderator
250 sign-ins 100 replies posted 50 solutions authored

Hi @Tomhe85,

 

As a pull-up resistor allows controlled current flow from the supply voltage source to the digital input pins, the address pins should be connected to Vdd using pull-up resistors. For minimum pull-up resistor value, please use the below formula:

Rmin = [Vdd - Vol (max)]/ Iol
            = (5 - 0.4) V/3 mA
            = 1.53 kΩ

So, you can use 4.7 kΩ pull-up resistors.

Thanks,
Ritwick

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ritwicksharma
Moderator
Moderator
Moderator
250 sign-ins 100 replies posted 50 solutions authored

Hi @Tomhe85,

 

As a pull-up resistor allows controlled current flow from the supply voltage source to the digital input pins, the address pins should be connected to Vdd using pull-up resistors. For minimum pull-up resistor value, please use the below formula:

Rmin = [Vdd - Vol (max)]/ Iol
            = (5 - 0.4) V/3 mA
            = 1.53 kΩ

So, you can use 4.7 kΩ pull-up resistors.

Thanks,
Ritwick

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Hi Ritwick,
thank you for the quick response. I was confused because there is a picture indicating a direct connection to VDD (refer to Figure 2). I thought that the address pins have some internal protection not mentioned in the datasheet.
From now I will use a pull-up resistor.
Have a nice day!

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