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TPS55010: Can I use 5Vin=>5Vout/400mA?

Satoshi
Guru 19485 points
Other Parts Discussed in Thread: TPS55010

Customer is trying to use TPS55010 by the following spec.
5Vin=>5Vout/400mA
Can they use without a problem?

When they can use, if there are a reference figure or a use example, please let me know.

Thank you for your consideration.

  • 0
    TI__Mastermind 35115 points

    Hi Satoshi,

    This can be done as long as the design is scaled accordingly for the higher current. The limitation on output power is mostly caused by the low-side FET current limit and the regulation needed by the customer. With a higher load on the output, it can be expected for the output voltage to droop more.

    I've input the requirements in the excel found in the link below. It shows that the low-side current limit may be hit with the EVM transformer that has a primary inductance of 2.5 µH. The primary inductance needs to be increased to make sure there is no issue meeting this load requirement.

    7384.TPS55010Tool_SingleOutput_5V@400mAoutput.xls

    It appears that the inductance will be too large based on equation 14, but this is actually not an issue with the operation. The inductance value of 5.0 µH is highlighted red because it exceeds this value. The trade off is slightly lower efficiency at full load as this higher inductance will reduce current ripple. The reduced current ripple prevents the design from having zero voltage switching of the high-side FET at heavier loads. It is beneficial for the magnetizing current ripple be large because it allows the current to go below zero before the low-side FET turns off. When the low-side FET turns off this negative current will pull the PH node high causing the voltage drop across the high-side FET to be near 0 before turning it on reducing switching loss.

    Best Regards,
    Anthony