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TMP401 with diode-connected NPN

Ian Williams
Mastermind 27715 points
Other Parts Discussed in Thread: TMP401, DXP

Posted on behalf of Vaibhav Shinde:

Hello,

I am a FAE who has been recently deployed to the field office in Chennai, India. Prior to this, I’ve been through the LEAP program in the US. 

My customer has the following query about TMP401:

The datasheet for TMP401 elucidates TMP401 connected to a pnp transistor or pnp diode connected transistor (Fig 11, Pg 6)

The customer wants to ensure that TMP401 can be connected with npn transistor as well (in the diode connected config as shown below). This involves connecting D- to ground. The datasheet guarantees that a npn transistor can be used. I just wanted to confirm if this configuration will work fine for their application?

If there are any application notes pertaining to this query or some customer has already used such schematic in their design, kindly mail me the same so that I can share it with our customer. 

Thanks for your help in advance. 

Kind Regards,

Vaibhav Shinde  
Field Applications Engineer
Texas Instruments

 

  • 0
    TI__Mastermind 27715 points

    Hello Vaibhav,

    There is no problem with using an NPN transistor with the TMP401 (or any other of our remote temp sensors). The critical thing to remember is that the transistor's internal diode must always be wired with the anode (+) connected to DXP and the cathode (-) connected to DXN. I've modified your schematic to show a standard NPN wired as a diode with the emitter connected to GND. I tested this configuration on the TMP513EVM (our only remote temp sensor EVM) using a standard 2N3904 transistor and got good results.

    To my knowledge there are no application notes specific to this request. As long as the customer connects their NPN transistor according to the attached schematic then the system should work properly.

    Best regards,

    Ian Williams
    Linear Applications Engineer
    Precision Linear and Sensing Products