TPS4811-Q1: Load dump

Stas Shamanin

Intellectual 450 points

Part Number: TPS4811-Q1
Other Parts Discussed in Thread: LM74930

Tool/software:

Hi!

Basically I need switch for inductive load for 48V system

But in our system we have spikes up to 110V

I want to move current sense part after MOSFET and protect VS with zener how it is done in LM74930 evaluation.

So VS pin is protected by zener and CS+, CS-, ISCP are protected by MOSFET

What do you think about this?

9 months ago

0 Stas Shamanin 9 months ago

Intellectual 450 points

Or maybe I can use LM74930 as switch without Q2 MOSFET (Q2 Source-Drain shorted on schematic) and MODE low?

0 Timothy Logan 9 months ago in reply to Stas Shamanin

TI__Mastermind 34935 points

Stas,

The high-side switch controller likely would not be able to handle the transient event. Is this an actual load dump event based off an ISO standard? We do test our devices to certain automotive standards and depending on the transient we might be able to support it based on the duration.

Best Regards,
Tim

0 Stas Shamanin 9 months ago in reply to Timothy Logan

Intellectual 450 points

We have a test like this from ISO7637-2 but instead of Us=112V we have 100V and td is not 50 uS but 50 mS.

ISO7637-2:

Our standard requirements:

But we have not 100V in laboratory, sometimes it goes to 105V.

That is why, maybe I can use LM74930 as switch but without forward MOSFET (or with MODE low)?

0 Timothy Logan 8 months ago in reply to Stas Shamanin

TI__Mastermind 34935 points

Stas,

I will loop someone in from our ideal diode team to comment if we have a device that would work for your application.

Best Regards,
Tim

0 Rakesh 8 months ago in reply to Timothy Logan

TI__Guru** 105361 points

Hi Stas,

You can use LM74930 as switch without Q2 to handle 100V/50ms transient events. you can configure the output to either cut-off or clamp as shown

Best Regards,

Rakesh

0 Stas Shamanin 8 months ago in reply to Rakesh

Intellectual 450 points

Hi!

What is difference in schematics for cut-off or clamp?

It is some play on OVCLAMP pin?

Thanks!

0 Rakesh 8 months ago in reply to Stas Shamanin

TI__Guru** 105361 points

Hi Stas,

In cut-off operation, input voltage is fed to OV pin. As soon as input crosses the Overvoltage threshold set by resistor divider, the controller turns-off the MOSFET.

In clamp mode of operation, the output voltage is fed to OV pin. The controller turns-off the MOSFET when output voltage exceeds the overvoltage threshold set by resistor divider. This leads to drop in Vout and then controller comes out of overvoltage condition, turning ON the MOSFET. The sequence continues operating the MOSFET in hysteretic control around OV threshold point.

Best Regards,

Rakesh

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TPS4811-Q1: Load dump