LM5143: current sense

Eric(Dongguan) Zhu

Intellectual 1450 points

Part Number: LM5143

hi team,

I see EVM and I wonder if you directly use the DCR of the inductor-L4 as a current sampling loop?

please tell the function of R17、R18、C29、R9 beside L4.

over 1 year ago

0 Timothy Hegarty over 1 year ago

TI__Mastermind 49317 points

Hi Eric,

Yes, these are components for inductor DCR current sense. The RC across the inductor should match the L/Rdcr time constant.

Regards,

Tim

0 Eric(Dongguan) Zhu over 1 year ago in reply to Timothy Hegarty

TI__Intellectual 1450 points

Tim,

thanks for reply.

1.Can you help explain the basic theory of inductor DCR current sense?

2. Which current sense method do you suggest?

0 Timothy Hegarty over 1 year ago in reply to Eric(Dongguan) Zhu

TI__Mastermind 49317 points

Just use the shunt (series current sense resistor) for easiest and accurate implementation. You can use the LM5143 quickstart file to assist with component selection.

0 Timothy Hegarty over 1 year ago in reply to Timothy Hegarty

TI__Mastermind 49317 points

For really high-current implementations where the shunt value is less than 2mΩ, you can consider inductor DCR current sensing. Just put an RC across the inductor, where RC = L/Rdcr (pole and zero match). The sense cap is typically set at 100nF, so just choose the R accordingly. I can dig up some links on DCR current sensing if you decide to go this way.

Regards,

Tim

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LM5143: current sense