LM2940-N: LM2940S-12/NOPB

Amit Kumar Dwivedi

Part Number: LM2940-N

Dear TI team,

Please provide short to ground current rating and thermal shutdown temperature limit details for LM2940-N (LM2940S-12/NOPB) part.

Electrical specification for the application are follows-

1. Vin- 14.2V

2. Vout- 12V/1A

And we are requesting you to

If we apply Vin=28V (Vbat), then this

9 months ago

0 Aaron Paxton 9 months ago

TI__Expert 4695 points

Hello,

The short to ground current limit can be found in the Electrical Characteristics table. I've included a snippet below:

The thermal shutdown is not a tested parameter. However, it's typically between 150C - 175C.

For your parameters, there would be 2.2W of dissipation. With a JEDEC layout, that is approximately a 90C rise in temperature. If the ambient temperature is greater than 35C, then the board layout needs to be optimized to improve thermal resistance.

~ Aaron

0 Amit Kumar Dwivedi 9 months ago in reply to Aaron Paxton

Prodigy 30 points

We need these two parameters, one of them (short circuit current is present in datasheet) but we also need thermal shutdown parameter (in which current rating parameter is tested).

Thanks for the support Aaron.

0 Aaron Paxton 9 months ago in reply to Amit Kumar Dwivedi

TI__Expert 4695 points

Hey Amit,

We can get you a typical thermal shutdown temperature but I need to reiterate that this is not a tested parameter. It's also not measured with a particular output current. If this works for you, it should take up to two weeks to get you a number. Let me know if you want to proceed this way.

~ Aaron

0 Amit Kumar Dwivedi 9 months ago in reply to Aaron Paxton

Prodigy 30 points

Hello Aaron,
Sorry for the late reply, but requesting you to provide the data related to shutdown temperature.

~ Amit

0 Aaron Paxton 9 months ago in reply to Amit Kumar Dwivedi

TI__Expert 4695 points

No problem, Amit. I'll get some units ordered and keep you updated.

~ Aaron

0 Amit Kumar Dwivedi 9 months ago in reply to Aaron Paxton

Prodigy 30 points

Thank you, Aaron.

Appreciate your kind and continuous support.

0 Kelsey Farr 8 months ago in reply to Amit Kumar Dwivedi

TI__Expert 4460 points

Hi Amit,

We tested LM2940S-12/NOPB, and the thermal shutdown temperature was measured to be 175°C. The thermal shutdown behavior indicates that there is no thermal shutdown hysteresis.

Regards,

Kelsey

0 Amit Kumar Dwivedi 8 months ago in reply to Kelsey Farr

Prodigy 30 points

Hello Kelsey,

Could you please share the test report with us?

Also, we need some more information,

1. As this IC is having inbuilt feature for the short to battery protection, so we wanted to know whether this IC will we protected in below condition,

Vstb=28V for 1 minute.

Thanks for your support.

Regards,

Amit Kumar Dwivedi

0 Aaron Paxton 8 months ago in reply to Amit Kumar Dwivedi

TI__Expert 4695 points

Hello Amit,

The test involved finding the effective RθJA value for the device and then calculating to find the Tshutdown point. The method is described in this app note: https://www.ti.com/lit/an/slva422/slva422.pdf

For the condition you are asking about, the device will go into current limit and subsequently cycle in and out of thermal shutdown.

~ Aaron

Power management

Power management forum

LM2940-N: LM2940S-12/NOPB