LMG3100R017: Low side switching only

Mathieu Raoux

Part Number: LMG3100R017

Tool/software:

Dear Support team,

I want to use the LMG3100Rxxx as a low side switch, pulling a load to GND.

I do not need the secondary power supply and I got a bit confuse with the HS pin liked to VIN in the datasheet. I also understand that this is internally linked to SRC and so to GND in my case.

Question 1 - What should I connect HS to in case of a low side switch only? My guess is nothing right?

Question 2 - I could not find the impedance of the input LI in the datasheet, I could not calculate anything as the current drawn by the input seems to be missing as well. Can you clarify the impedance of the LI pin?

Question 3 - I saw in the forum that you could share a Spice model of the device but could not find it as a direct download, could you please share the spice model with me?

Thanks in advance for your help and with my Br.

Mathieu

3 months ago

0 Pratik Adibatla 3 months ago

TI__Expert 7473 points

Hi Mathieu,

Thanks a lot for reaching out. Please see my responses.

Mathieu Raoux said:
Question 1 - What should I connect HS to in case of a low side switch only? My guess is nothing right?

HS should be tied to the Drain.

Mathieu Raoux said:
Question 2 - I could not find the impedance of the input LI in the datasheet, I could not calculate anything as the current drawn by the input seems to be missing as well. Can you clarify the impedance of the LI pin?

It's provided in the datasheet as shown below:

Mathieu Raoux said:
Question 3 - I saw in the forum that you could share a Spice model of the device but could not find it as a direct download, could you please share the spice model with me?

We only have Simplis and PLECS model for this device. Please see attached.

LMG3100R017 PLECS.zip

1030.LMG3100R017 Simplis.zip

Hope this helps! Please click the green button if this resolves the issue, if not feel free to ask more.

Best,

Pratik A.

0 Mathieu Raoux 3 months ago in reply to Pratik Adibatla

Prodigy 10 points

Dear Pratik,

Thanks for Question 1 and 3.

For Question 2 I'm a bit surprise as for my the impedance Z of the Input is in parallel with the input pull down resistor. The pull down thus influence the overall impedance value of the input but is not the impedance on its how right? Or I am getting something wrong?

Thanks again for you clarification.

BR.

Mathieu

0 Pratik Adibatla 3 months ago in reply to Mathieu Raoux

TI__Expert 7473 points

Hi Mathieu,

You're correct. You have to account for the input pull down resistor for your impedance calculations.

Best,

Pratik A.

0 Mathieu Raoux 3 months ago in reply to Pratik Adibatla

Prodigy 10 points

Hi Pratik,

Thanks but how do I get the say impedance Z of the input?

If I only know the pull down and nothing else it's not possible to calculate it...

Br.

Mathieu

0 Pratik Adibatla 3 months ago in reply to Mathieu Raoux

TI__Expert 7473 points

Hi Mathieu,

Just the pull down can be used here as the input impedance.

B.R.,

Pratik

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LMG3100R017: Low side switching only