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TPS54618-Q1 - Possible to Run Continuously @ Vin = 6.5V?

Other Parts Discussed in Thread: TPS54618-Q1, ABS

Is it possible/acceptable to run the TPS54618-Q1 at a Vin = 6.5V "continuously"?  The specification shows the ABS MAX for Vin = 7.0V and the "Operating Input Voltage" under "Electrical Characteristics" shows Vin = 2.95V to 6.0V.

I would like to know based on any data we have if it is possible to have the device running with a Vin = 6.5V for "long" durations.  For example if the device is fed by another supply that typically outputs 6.0V but may have excursions up to 6.5V that last minutes or hours will this be OK for the TPS54618-Q1?

Kind Regards,
Marc

  • Hi Mark -

    The TPS54618Q absolute maximum voltage is specified at 7V. As long as the VIN pins do not exceed 7V, then the reliability of the device is still guaranteed. This includes any high frequency "ringing" or ripple due to switching activity. 

    We specify this device up to 6V, because 6V is the maximum recommended operating voltage for the TPS54618Q1. We recommend it up to 6V to allow some margin for the ripple/ringing etc... The device has only been characterized up to 6V, which means that all of the parametric specs are only tested/guaranteed up to 6V. Operation at 6.5V is possible, but some of the parametrics may be slightly off the EC table spec. 

  • One thing to consider is the PH voltage at light loads. With forced CCM the low-side MOSFET will have negative current at light loads. When the low-side MOSFET turns off with negative current the only path for this current to go is through the body diode of the high-side MOSFET. This puts a voltage stress on the PH pin of VIN + Vbody. It depends on the actual peak negative current but Vbody will likely be greater than 0.5 V. With 6.5 V input the PH voltage would exceed the 7 V absolute maximum.

  • OK.  Thanks for all the feedback.

    Marc