TPS53319EVM Output Voltage

Muthukumar Rajendran

Other Parts Discussed in Thread: TPS548A20EVM-737

Hi,

I have TPS53319EVM eval board. I am not able to change the output voltage to 5V even after changing the feedback resistor to 73K.

Is there any other settings to be changed for getting 5V output?

Please let me know.

Thanks

over 8 years ago

0 JohnTucker over 8 years ago

TI__Guru**** 191445 points

There may be a few additional changes required. I recommend you work thru the detailed design procedure in the datasheet at section 9.2.1.2 and since the EVM uses ceramic capacitors for the output also the equations of section 8.3.13 and change the EVM components as required. Let me know if this works for you.

0 Robert Kim over 6 years ago in reply to JohnTucker

Prodigy 60 points

In step three, equation 15 there is a parameter for RDS_on. Where do I find its value? I do not see it under the specifications section.
I am also trying to design a 5V supply, but before that I want to make sure my calculations are correct by cross referencing my numbers with the eval board.

0 JohnTucker over 6 years ago in reply to Robert Kim

TI__Guru**** 191445 points

You can substitute Rtrip/12300 for Vtrip/(32 x RDSon)

0 Robert Kim over 6 years ago in reply to JohnTucker

Prodigy 60 points

Got it.
I think there is something wrong with my math for the R1 calculations. I get 9837 Ohm when the actual R1 is R10 + R11 in the eval kit which is 24700 Ohm. My calculated L is 483nH (vs 500nH in the eval kit) and the ESR is 0.004167 (used 500000 Hz f_sw)
Does the inductor have to change to be able to output 5V? Isn't the inductor only used for the current ripple?
Could you please provide a reference design for a 5V out configuration?
Thanks.
Rob

0 JohnTucker over 6 years ago in reply to Robert Kim

TI__Guru**** 191445 points

I don't personally have any 5 V reference designs. I would recommend you try using the Webench on line application to generate your design.

0 Robert Kim over 6 years ago in reply to JohnTucker

Prodigy 60 points

Seems like the output voltage configuration with the TPS548A20EVM-737 is more straightforward, as simple as just changing a resistor. I still don't understand why changing the resistor with TPS53319EVM does not seem to do the same thing.

0 JohnTucker over 6 years ago in reply to Robert Kim

TI__Guru**** 191445 points

You should be able to get 5 V output by changing R10 to 73.2 k and removing R23, R24 and C20.

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TPS53319EVM Output Voltage