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TPS92515HV: Need a details regarding IC marking

Divakar ethiraj
Prodigy 20 points
Part Number: TPS92515HV

Tool/software:

Hi team

We are using the above BUCK IC but in which we have two different markings

1. 37 TI 15Qx

2. 3C TI 15Qx

Please let us know whether both are same IC's.

If yes what is the difference between 3C and 37.

Because currently we are facing an issue in BUCK output current. 

1. In 37 TI 15Qx output of LED current correctly matches with the VADJ

For ex: LED current is 840mA , of VIADJ 0.937V

2. Where us the IC with 3C TI 15QX the LED current is not accurate

Ex: LED current is 700mA with same VIADJ of 0.937V

So we are trying to Debug the issue.

Currently I required your support on this.

Thanks & Regards

Divakar B

  • 0
    TI__Mastermind 23326 points

    Hello Divakar,

    The first two characters are date codes.  This should be the same silicon.  Did you swap parts and boards to make sure it isn't a board issue and check to see if the problem follows the IC?  Is this just one device or does this happen to many devices?  If you did that and it follows the part then you need to start taking waveforms to see why this is so far off.  We would want inductor current, switch node, output voltage and Viadj.  

    -fhoude

  • 0 in reply to fhoude
    Prodigy 20 points

    Hi Fhoude

    Good day!

    Thank you so much for your reply.

    First of all I am sorry for the above question.

    Please note I have faced the above output current issue in both the IC's.

    I have done a rework in my design.

    As per the datasheet recommendations Layout pattern "Kelvin connection to Rsense" is not follwed . After the rework now I am getting the output LED current of around 811mA (mean current measure in scope).

    But my requirement is for 840mA. And please note from the datasheet I have used the equation 6.

    And I have considered all the components tolerances and the parameters value (vcdt_offset , voft, tdel, td(off) ) from datasheet.

    So in that case the LED current should be

    Min: 796mA

    Typ: 841 mA

    Max: 914 mA

    So the measured current is with the calculated range.

    So will this the case for the output current. Why the typical current is not achieved.

    Output voltage: 6.25

    VIADJ: 990mV

    Components:

    Inductor: 47uH

    Coff: 1nf

    Roff: 8.2k

    Vin: 9v to 16v

    Output voltage: 6.5V

    Please let us know your comments.

    Thanks and regards 

    Divakar 

  • 0 in reply to Divakar ethiraj
    Prodigy 20 points

    Sorry forgot to mention and the above measured current (811mA) is for 13.5V condition....

  • 0 in reply to Divakar ethiraj
    TI__Mastermind 23326 points

    Please send me your schematic so I can review it.