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TPS737: Could you tell me about TPS73701 ?

Part Number: TPS737
Other Parts Discussed in Thread: DEM-SOT223LDO,

My customer is using TPS73701DCQR.

Customers designed with peripheral component constants described below.

Phenomenon①:There was a device whose output voltage dropped by about 0.5V when the load by 200mA.

Phenomenon②:However, if it is confirmed by the following constants, the output voltage does not decrease.

We confirmed the target sample on TI's general purpose EVM "DEM-SOT223LDO", but the same phenomenon has occurred.

(I guess customer is no error in pattern design from this result.)

<Comment on peripheral component constants>

· I think that customers designing at peripheral capacitors as specified.

· Although there is no description at datasheet of the feedback resistor for the 4.5 V setting, it is the recommended range of the output voltage setting.


<Question>
From this situation, can you tell me what is caused by (as you can guess)?

Best regards,

Masumi Sekiguchi

  • Hi Masumi-san,

    The resistors and capacitors selected are within the datasheet guidelines. Are you able to provide a scopeshot of Vin, Vout, and Iout? The scopeshot will help us debug the application.

    Very Respectfully,
    Ryan
  • Thanks for the reply.

    Although it is confirmation of VOUT only, I will send it.

    This time, confirmation of ① and ② was confirmed by sample of good and defective products.

    Phenomenon ①:VOUT = 4.5 V

    IOUT = 0 mA

                                                Good Product                                                                                                         Defective Products

    IOUT = 200 mA

                                                Good Product                                                                                                         Defective Products

    ⇒Result:The phenomenon is reproduced (right side figure).

    Phenomenon ②:VOUT = 3.3 V

    IOUT = 0 mA

                                                Good Product                                                                                                         Defective Products

    IOUT = 200 mA

                                                Good Product                                                                                                         Defective Products

    ⇒Result:The phenomenon is not reproduced (right side figure).

  • Hi Masumi-san,

    For clarification, was when you say "Good Product" and "Defective Product" does product mean the TPS737 or the customer's end product?

    It looks like the defective product is going into dropout at 200 mA when it is set to 4.5 V. Can you confirm that the input voltage remains steady at 5 V?

    Also when you have Vout set to 3.3 V, is your Vin still 5 V?

    Very Respectfully,
    Ryan
  • >For clarification, was when you say "Good Product" and "Defective Product" does product mean the TPS737 or the customer's end product?

    ⇒ No.

     "Good Product" and "Defective Product" are the same sample of TPS73701 meaning reproduced sample of this phenomenon and unreproduced sample.

     I will add it because my explanation is insufficient.

    <Additional notes>

    Customer discovered this phenomenon on the customer's board and replaced it with a new-sample item (a sample not reproduced),so the phenomenon no

    reproduces..

    To distinguish things that are not influenced by pattern design, I confirmed whether the same thing was reproduced by TI's recommended EVM.

    >It looks like the defective product is going into dropout at 200 mA when it is set to 4.5 V. Can you confirm that the input voltage remains steady at 5 V?

    ⇒ I'm sorry. It is difficult to take additional waveforms.

    >Also when you have Vout set to 3.3 V, is your Vin still 5 V?
    ⇒ Yes. When setting VOUT = 3.3 V, VIN is 5.0 V.

    Best regards,

    Masumi Sekiguchi