LM5050-1-Q1: PIN3 OFF MOSFET turn on issue

Bryan Chang

Part Number: LM5050-1-Q1
Other Parts Discussed in Thread: LM5050-1, LM74800-Q1

Tool/software:

LM5050.pdf

Hi Ti member ,

When TBTA_VBUS 20V in , pin 3 OFF pin pull High (3.3V) , output (VA2) is about 18V~19V

Pin 5 gate pin is about 19V

It can not turn off via pin 3 OFF pin (3.3V), is that correct ?

It is different from below data sheet definition :

Please answer it , thanks a lot

Bryan

0 Shiven Dhir 16 days ago

Hi Bryan,

LM5050-1 cannot drive back-to-back FETs and can only drive an ideal diode FET.

Regards,

Shiven Dhir

0 Bryan Chang 15 days ago in reply to Shiven Dhir

Hi Shiven,

Thanks a lot for your answer, it solves my QA

Sorry, another QA:

Can I use TPS259474A to drive back-to-back FETs (To replace following LM5050 circuit; TBTA_VBUS is 20V )

PS, JDC_AC to VA2 keep using LM5050

Thanks a lot for your supports.

Bryan

0 Shiven Dhir 15 days ago in reply to Bryan Chang

Hi Bryan,

You should be able to use it. As far you don't violate the abs-max which depends on the level of transients on the 20V rail.

Otherwise, you can also choose to use LM74800-Q1 which can drive b2b FETs and block reverse current. It is rated for 65V.

Regards,

Shiven Dhir

+1 Bryan Chang 10 days ago in reply to Shiven Dhir

I get it, thanks a lot

Bryan