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TPS56528: Design review

Part Number: TPS56528


My customer is using the TPS56528DDAR with the following conditions to supply an XFP optical module power.

    - VIN = 12V, VOUT = 5V, IOUT = 1.24A(Inrush current=3.48A)

They designed the TPS56528 with the follwoing TI's simulation result shown below.

1. Please review whether there is a problem with the customer's schematic.

2. The following capture image is the initial power-up of the TPS56528. While the output is ramping up from 0V to 5V, the symptom of about 10mS holding at about 2.24V level is observed.

    2-1. Is this symptom normal? Please tell us the cause of the symptom and how to get rid of it.

    2-2. Are there any expected problems with this symptom?


Thank you.


  • Hi JH,

    I will make review of the schematic. Could you please share the layout of customer?

    Could you please help capture waveforms of Vin, EN, SW, Vout? This could be better for analysis.

    BTW, may I check what is EE and TAM of customer? Since TPS56528 is an old part, do they have plan for substituting it with new part? 



  • Hi Zixu,

    Thanks for your reply.

    Here is the customer's layout.

    The above captured image is the VOUT of the TPS56528. VIN,EN,SW images will be updated ASAP.

    The customer makes wired optical communications equipment.

    They are already testing the PBA. Are there any new parts that is pin compatible?

    Could you please provide the comparative data between TPS56528 and new part?



  • Hi JH,

    Thanks for your reply!

    The schematic looks good for me. 

    I still have some questions for customer application:

    What is their setup(Vin, Vout, Iout, both typical and maximum value)? Do we have any data for the estimated quantity of TPS56528 used in their project?

    Please send email to my address:, we will discuss through email.