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TPS54561-Q1: Output Capability about TPS54561-Q1

Chuan Gao
Prodigy 125 points
Part Number: TPS54561-Q1

Hello

I have a question about TPS54561-Q1 output capability.

 

In our design, we need current having 5.3A output capability.

And we try to use TPS54561-Q1.

However this regulator could support 5A output capability which could be found in the datasheet(in Tittle and Description epsoide).

  1. Is ‘5A’ the limit of output capability?

  2.  To get more output current capability, we try to increase the inductance , so we could get lower ripple current so that even average output current is 5.3A ,the peak current through Switch MOS will not exceed the 6.3A.  Is that possible?

-we will comply with the datasheet that the minimum ripple should be greater than 150mA.

 

 

Some information about our application:

Input:16-36V

Output:3V3

Operating switching freq:1.5MHz

Load current (worst case):5.3A

  • 0
    TI__Genius 11085 points
    The current limit given on the datasheet is driven by the current limits, the size of the power FET and thermal capability. If you design does not require long life time operation, I'd say it is ok to operate with 5.3A DC current. You can increase the L slightly to reduce the ripple. But I don't recommend reduce it to as low as 150mA. The example in the DS has more than 1.5A ripple. The peak current is DC current + 1/2 ripple. Keep in mind this device is current mode controlled, certain amount of ripple is needed for a good signal-to-noise ratio for the control loop.
    One observation is that your switching frequency is 1.5MHz. The concern is power loss will be significant at the worst case: max Vin, max load and high switching frequency. I'd suggest leave options of lower frequency operation on your board, in case thermal becomes an issue.
  • 0 in reply to YangZhang
    Prodigy 125 points

    Hello YangZhang

    Thanks for your reply!

    You mentioned that 5.3A DC current load could have some impact on life time. Would you please give us more details ? because we could not find any violation in the DS about 5.3A DC current except for the "recommended operating conditions" in Page 4.

    Do you mean this DC current will lead to the peak current exceeding the current limit(6.3A) in the DS?

    Because I found the formula in the DS to calculate ripple current which is controllable by L and Fsw.

    Iripple=Vo*(Vimax-Vo)/(Vimax* L* fsw)

     

    Thanks.