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TPS54561: PWRGD pin begins to sporadically drop to Low at high loads.

toshio kubota
Prodigy 50 points
Part Number: TPS54561

Tool/software:

Hi.

We designed a 5V power supply circuit using the TPS54561.
Following the webench design, also we have designed the board and are evaluating its performance.
webench.ti.com/.../SDP.cgi
(L1 was modified to 10uH because it was out of stock.)

We are currently looking at the behavior under high loads, and while the expected design load is 5A and the product requirement is 3A, the PWRGD pin begins to sporadically drop to the Low level at loads of approximately 1.6A or more.
What is happening here?
What should we pay attention to?

circuit is below.

and BOM is below.

Rcomp R131 ERJ2RKF1652X
R132 ERJ2RKF2002X
Rt R133 ERJ6ENF1333V
Cout C136 GRM31CR61A476ME15L
Ccomp C132 GRM1882C1H182JA01D
Rfbb R136 ERJ2RKF1002X
R137 ERJ2RKF1501X
Cin C131 GRM31CR71H475KA12L
Ccomp2 C133 GCM1555C1H100FA16
Rpg R138 ERJ2RKF1001X
Css C134 GRM1882C1H272JA01D
U1 IC131 TPS54561DPRT
L1 L131 IHLP5050FDER100M01
D1 CD131 RBQ20NS45ATL
Rfbt R134 ERJ2RKF4302X
R135 ERJ2RKF1742X
Cboot C135 GRM155R71H104KE14D

thank you.

  • 0
    Prodigy 50 points

    Hi all.

    I solved the problem myself.
    The cause was that the output capacitor was too small. After adding a chemical capacitor (100uF/25V) as the output capacitor, the PWRGD pin remained at H up to the expected load of 3A.

    thank you.