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TPS62870-Q1: Rated Output voltage is not obtained when VSEL pin connected to 6.2Kohm to GND

Aishwarya S
Prodigy 80 points
Part Number: TPS62870-Q1
Other Parts Discussed in Thread: TPS62870,

Tool/software:

Regarding the Part - TPS62870
We have noticed that the simulation model provided and the datasheet data are not matching.
With reference to the below attached data kindly support to resolve this issue. 
Simulation Notes in TI SPICE model (model downloaded from TI website) : 
Four default voltage for start-up can be selected by connecting appropriate resistors to VSEL pins.(Refer Datasheet)

The parameter VOUT has been used to set output voltage other than these four default vaoltages. When VSEL is left floating, Output voltge is set by the VOUT parameter.

Simulation configuration for VSEL: RVSEL= 6.2Kohms ( Vsel is connected to Ground via 6.2K Ohms in our application ) 
Vout obtained for this model with Vout specified in F11 Window - Steady state analysis is 0.5V 

  • 0
    TI__Genius 16871 points

    Hi Aishwarya,

    Thanks for insight and detail explanation.

    TPS62870-Q1 part has multiple part number and model is following default setting of following part. 

    There are many spin parts for this device with default settings and that's the reason best practice to make VSEL pin floating and set output voltage through F11 window as you mentioned.

    I didn't understand your concern. Is model not working for your application?  Could you help to provide your operating conditions?

    Best regards,

    Tanvee

  • 0 in reply to Tanvee
    Prodigy 80 points

    Hi Tanvee,

    The part number what we are using in our application is TPS62870QWRXSRQ1 and in this part VSEL is connected 6.2 kΩ to GND

    As per datasheet (DEVICE options) and Simulation notes - we can set the output voltage by connecting VSEL= 6.2 kΩ to GND.

    This same configuration is used in our application. when Simulated, the rated output voltage is not met (0.85V) - we got 0.5V as output voltage

    Out test condition: VIN=3.3V, ILOAD=4.373A, VOUT=0.85V

    Please find the simulation schematics and results below. I hope this is clear. Let me know if you need further details

  • +1 in reply to Aishwarya S
    TI__Genius 16871 points

    Hi Aishwarya,

    I understand your point but let me clear once again there no different model for each part number as device internal architecture is same.

    You have to use same model for you application and follow the step

    • Keep vsel pin unconnected 
    • Set the output voltage through editor window for you application.

    Let me know if you still have question on VSEL pin. 

    Best regards,

    Tanvee