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TPS7B81-Q1: NC Connect to input risk evaluation

Part Number: TPS7B81-Q1
Other Parts Discussed in Thread: TPS7B87-Q1, TPS7B81, TPS7B82-Q1

Hi Expert,

Now TPS7B81-Q1 is replacing TLE4252 in a customer. When we check the schematic and layout, PIN 4 (DNC) was connected to input voltage. Customer can't change the layout and schematic now.

Here is the package customer used:

  • is there any issue if we connect DNC ti Vin?
  • How about TPS7B820-Q1 and TPS7B87-Q1?

Best Regards

Songzhen Guo

  • Hi Songzhen, 

    The DNC pin is normally for programming the device in production and is recommended to be floating to avoid the LDO entering undesired modes. I would not risk connecting the DNC to the Vin as we don't know what kind of Vin the application may have and there is a chance the LDO could enter a test mode. 

    TPS7B81, TP7B82 both have DNC. TPS7B87 has a different package and the NC pins in TPS7B87 are truly not connected to the internal die and they can be shorted to Vin. Do you think they could use TPS7B87? 

    Regards, 
    Jason

  • Hi Jason,

    Thanks for your help.

    For TPS7B81-Q1 and TPS7B82-Q1, Vin connect to 12V battery(9~36V range), NC connect to 5V, 5V is a fix voltage. Will this trigger test mode?  NC doesn't suitable for customer's application.  Could you check it for us? Thanks.

  • Hi Songzhen, 

    Sorry for my late response. Please allow 1-2 business days for me to confirm this with our test and design team. You mentioned "NC" but you actually were talking about the "DNC"(Pin4) in KVU, right? 

    Regards, 
    Jason Song

  • Hi Songzhen, 

    I have a discussion with the team, and the DNC pin has active circuity and we don't have test data with a 5V biased voltage on the pin. Is there a way for them to open the connections of the pin? Do you see any other alternative solutions? 

    Regards, 
    Jason Song