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LM2743 COUT Max [GDCanada]

LeonardEllis
Guru 71536 points
Other Parts Discussed in Thread: LM2743

When set up in Webench for VIN 11.4>12.6, VOUT = 0.90V, IOUT = 10.5A, COUT is selected as 330uF.  If I edit COUT, the upper limit is shown to be 419uF.  The datasheet does not specify a COUT MAX, and pg 20 states use of 560uF to handle transients. 

Why is Webench not allowing a COUT > 330uF?  How can I edit the design to use, let's say, a 470uF cap and two 10uF caps in parallel = 490uF?

~Leonard 

GDCanada_LM2743_11Vto0V9_10A[wc].pdf

 

  • 0
    TI__Intellectual 2360 points
    Hi Leonard,
    The minimum value for Cout and its maximum ESR are determined to meet the target of 1% maximum output ripple. The maximum value for Cout is simply 2x the minimum. The resulting range of Cout and ESR should give good frequency response and low output ripple voltage. The stable frequency response should also translate to good transient response. If you wish to increase Cout beyond the suggested maximum, you can create a "custom" Cout. From the view that shows suggested alternate choices for Cout, go to the bottom of the page and click the red "custom" button. You can enter your desired value for Cout there. The design operating values will be updated to reflect your new component choice.