LM7480-Q1: LM74801-Q1

Thomas Preußer

Part Number: LM7480-Q1
Other Parts Discussed in Thread: LM74800-Q1

Hi,

we´re using the LM74801 in a common drain configuration. The Dgate MOSFET has 2,3mOhms only, and at currents app. lower than 5amps the reverse battery protection gets active due to (presumably) votage disturbance (EMI). Additional capacitance between pins A and C brings little improvement but will not eliminate the problem. Are there other measure I can take to achieve more robustness against EMI and to avoid unwanted switch off of the Dgate MOSFET?

Thank you help!!

Regards Thomas

9 months ago

0 Praveen GD 9 months ago

TI__Guru 57737 points

Hi Thomas,

The DGATE oscillations that you see at light load is due to the linear gate control. Please refer to the e2e FAQs below,

0 Thomas Preußer 9 months ago in reply to Praveen GD

Prodigy 10 points

Hi Praveen,

thanks for your quick reply. The LM74801-Q1 does not comprise a linear gate control. The gate is hard switched on/off.

And the forward voltage even is significantly lower than 10mV in light load condition.

I think the problem is due to the small negative voltage of (A-C) Threshold for Fast Reverse Current Blocking of –6.4 ... –1.3 mV only.

The forward voltage under light load is only +1...10mV, so that small voltage disturbance caused by MOSFET switching of the supplied circuit the DGate switches off.

Do I have a chance to suppress switching disturbance at the LM74801, or to delay the DGATE switching?

Kind regards

Thomas

0 Praveen GD 9 months ago in reply to Thomas Preußer

TI__Guru 57737 points

Hi Thomas,

You are right! LM74800-Q1 has linear gate control where as LM74801-Q1 has comparator only based reverse current blocking circuit. Sorry for over looking that you are using 801.

Can you give us more information on the voltage disturbance that is being applied to the LM74801-Q1 ? Is it a standard test ? Please share waveforms if available.

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LM7480-Q1: LM74801-Q1