LM5069: Schematic review and no output on some LM5069

Gary Teng

Part Number: LM5069

Hi all,

My customer want to use LM5069 to protect their 20V adapter input in type-c application. Their schematic is as below.

In their first board test, 9/50 devices are failed: the control gate can't be turned on successfully. Customer change PWM resistor (From 15.8K to 12.5K), Rsense (From 5mohm to 4mohm) and Ctimer (from 0.15uF to 0.1uF) but those failed ICs are still failed. And no impedance issue found on those ICs. We put those failed IC to EVM and it's failed on EVM.

1. Is there any issue on their schematic?

2. Is there any possible about damage through input path? Or anything we can check for device's activity? VIN/UVLO/OVLO?

Thanks for your kindly help.

Regards,

Gary Teng

over 3 years ago

0 Rakesh over 3 years ago

TI__Guru* 95751 points

Hi Gary,

Please fill the design calculator and send me for review. It is available under product folder.

Looks like you have more startup load than estimated.

Best Regards, Rakesh

0 user5021594 over 3 years ago in reply to Rakesh

Prodigy 65 points

Dear Rakesh,

Please see the attached, thanks.

BR, C.H. Yang

LM5069_Design_Calculator_REV_C-0831 - MCC_MCB160N10Y.XLSX

0 Rakesh over 3 years ago in reply to user5021594

TI__Guru* 95751 points

Hi Gary,

Design sheet looks fine. Do you have any additional load other than the capacitive load entered in the design sheet?

What type of load is connected to the output ?

Best Regards, Rakesh

0 user5021594 over 3 years ago in reply to Rakesh

Prodigy 65 points

Dear Rakesh,

No other capacitive load.

The Boost DC/DC solution (MP3428A) is connected to the output..

BR, C.H. Yang

0 Rakesh over 3 years ago in reply to user5021594

TI__Guru* 95751 points

Hi,

You have to enable the boost converter once the hot-swap output is fully enhanced to avoid overloading the hot-swap during startup. Using PG signal of LM5069 to enable MP3428A and check.

Best Regards, Rakesh

0 user5021594 over 3 years ago in reply to Rakesh

Prodigy 65 points

Dear Rakesh,

Not only full loading or overloading, the issue also found in light loading.

When I just plugged in adapter and cable to the host(NB), the control gate can't be turned on.

BR, C.H. Yang

0 Rakesh over 3 years ago in reply to user5021594

TI__Guru* 95751 points

Hi Yang,

The capacitor at the output of boost converter will be additional startup load to the hotswap because it completes the path through the boost inductor and FET QB2.

Can you check

1. Remove boost inductor and see whether the system is able to power up

2. Increase either the power limit to 100W OR timer cap to 330nF and test.

Best Regards, Rakesh

Power management

Power management forum

LM5069: Schematic review and no output on some LM5069