Webench/LM5118EVAL: LM5118

Mario Paroni

Part Number: LM5118EVAL
Other Parts Discussed in Thread: LM5118,

Tool/software: Webench

Hello,

for an application with Vin from 8 to 75 VDC I have developed an identical circuit board to the all'evalution board LM5118EVAL. The maximum current in each case is always less than 2.5A, while the external temperature can reach 50 ° C. So far in 2 cases of 100 boards in use, it has broken the integrated LM5118, is there a configuration problem with the current loop?

I noticed that with the WEBENCH simulator it's not longer possible to do the simulation of this component with these input voltages and output currents greater than 2A, should I to redesign the device for currents less then 3A?

Thank you

Mario

over 7 years ago

0 Garrett Roecker over 7 years ago

TI__Mastermind 21720 points

Mario,

If it is possible can you post the schematic? I just want to clarify what you mean by Identical to the evaluation board.
Also when you say 'broken the integrated LM5118" what do you mean? Is there a pin that is damaged? Is it an external component?

Thanks,

Garrett

0 Mario Paroni over 7 years ago in reply to Garrett Roecker

Prodigy 185 points

Hi Garrett.

When not worked it was broken the LM5118 becouse after have changed it, the power supply it began operating. Observing the behavior of integrated with the oscilloscope, you could see that in the fault condition it will turn on and turn off constantly. The voltage at output due to this pulse mode of operation was thus reduced from 12V to 3.5V. Below you can see the schematic,

Thank you

Mario

0 Mario Paroni over 7 years ago in reply to Mario Paroni

Prodigy 185 points

0 Garrett Roecker over 7 years ago in reply to Mario Paroni

TI__Mastermind 21720 points

Mario,

First, test the circuit using an external UVLO signal. This can be a pulled up to 5V and see if the IC operates as intended at an ambient temperature of 50C. If this fixes the problem please add a 12V Zener diode from the UVLO pin to GND.

Second, adding a diode between the VCC and HB pin should help reduce the power dissipation in the LM5118 IC when operating at higher ambient temperatures.

Thanks,

Garrett

0 Mario Paroni over 7 years ago in reply to Garrett Roecker

Prodigy 185 points

Hi Garrett,

thanks for your answer, just returned to repair a board I'll make the corrections and then let you know the results.

Thanks

Mario

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Webench/LM5118EVAL: LM5118