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TPS54227: What is the output voltage of TPS54227 limitted to 7V by?

Kazuya Nakai59
Guru 20140 points
Part Number: TPS54227

 Hello guys,

 One of our customers is considering using TPS54227. They have a few questions as the follows.

Q1. In TPS54227 case, the output of DCDC using the device is not connected to the device directly (Divided output voltage is connected to VFB. But it is not connected directly.) . What is the output voltage of TPS54227 limitted to 7V by?

Q2. If the output voltage is set to 7.5V or 8V, what is happend?

 Your answers would be appreciated.

 Best regards,

 Kazuya Nakai.

  • 0
    TI__Expert 4875 points
    Hi Kazuya,

    Q1: TPS54227 is a DCAP2 device. DCAP2 means adaptive constant on time control for fixed frequency. For transient response, the only way to regulate the output voltage is to change the HSFET off time. For high duty cycle application, the margin for HSFET off time is small and the load transient will be worse than small duty application. This is the reason why we define the output voltage no higher than 7V.

    Q2: Vout set to be 7.5V or 8V is applicable. The only thing needed to keep in mind is that the input voltage should be high enough, like 12V. Bigger inductor value needed to consider to get the same output voltage ripple. And Cff is also needed to take into account for better loop response.

    Best,
    Anthony
  • 0 in reply to Anthony Lang
    Guru 20140 points
    Hi Anthony,

    Thank you very much for your reply. It is very helpful for the customer and me.

    Best regards,
    Kazuya Nakai.