LM5143-Q1: The conductor is hot even no load

xiao weihua

Part Number: LM5143-Q1

hello

I designed a power board and the attatched is my schematic. the problem is ，When no-load, the power consumption is also very large, and the inductor heats seriously.

over 2 years ago

0 xiao weihua over 2 years ago

Intellectual 480 points

pw_240w_28v_0623.pdf

0 Timothy Hegarty over 2 years ago in reply to xiao weihua

TI__Mastermind 49537 points

Hello Xiao,

Please send a completed LM5143-Q1 quickstart calculator for this design so we can review component losses.

These are 1.4mOhm FETs with high Qg (30nC at 5V). Based on the 28V to 5V conversion (relatively low duty cycle), choose a higher Rdson FET with lower Qg to reduce switching losses.

Recommendation is to set all gate resistors to 0 Ohms. Boot caps can be 0.1-0.22uF and VDDA cap should be 1uF (10uF is high for that).

Regards,

Tim

0 xiao weihua over 2 years ago in reply to Timothy Hegarty

Intellectual 480 points

there are many glictchs on gate signal of NMOS, what is the problem?

+1 Timothy Hegarty over 2 years ago in reply to xiao weihua

TI__Mastermind 49537 points

Looks like a stability problem. Please check your compensation values using the quickstart calculator (use the correct ESR for the output electrolytic caps).

Regards,

Tim

Power management

Power management forum

LM5143-Q1: The conductor is hot even no load