LM5145: Varying the output from 13V/3.5A to 30V/11A

Jamie Mitchell

Part Number: LM5145
Other Parts Discussed in Thread: DAC63204

Tool/software:

Hello!

I need a circuit that can vary the power delivered to a resistive load. The input is a consistent 48V, and the output needs to vary based on the desired current. I'm hoping that I can achieve this with the LM5145 and a DAC63204 injecting voltage into the FB network.

I used WEBENCH to design a circuit for the top end, and it provided this:

WEBENCH (ID = A78FCE84726613A0)

I simulated a similar (higher top end) circuit in TINA with a voltage controlled feedback resistor, and it looks stable:

Is this feasible? Am I heading down the right path here? Any insight would be extremely appreciated, buck converter stability isn't in my wheelhouse.

Thank you,

Jamie

8 months ago

0 Timothy Hegarty 8 months ago

TI__Guru* 75462 points

Hi Jamie,

Please refer to the quickstart calculator for assistance with the design: https://www.ti.com/tool/LM5145DESIGN-CALC

Tim

0 Jamie Mitchell 8 months ago in reply to Timothy Hegarty

Prodigy 10 points

Thanks for the reply! Does that mean that WEBENCH should not be used for this device? Would you be able to provide any suggestions on how to best use the quickstart tool for a range of output voltages and currents? Is there any concern in general with using the LM5145 in this fashion?

0 Timothy Hegarty 7 months ago in reply to Jamie Mitchell

TI__Guru* 75462 points

Hi Jamie,

Sorry I missed your reply. In terms of a wide VOUT range, I recommend designing the compensation at max Vout where the Cout (ceramic) value is lowest. Then fix the compensation values and check min Vout with the increased ceramic Cout value as needed. I'm not sure if WEBENCH is able to handle wide VOUT, hence the recommendation to leverage the quickstart.

Regards,

Tim

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LM5145: Varying the output from 13V/3.5A to 30V/11A