LM293: OverCurrent Dection Spurious Triggering

James Zhan

Part Number: LM293
Other Parts Discussed in Thread: LM2903

Hi team,

My customer use LM293 for over current detection, but recently they have some spurious triggering.

The new board run about 2 hours and then have the false triggering. After restart, system run about 20 mins and then false triggering again.

NOTE: The board temperature is about 90℃

question:

1. Will this 90℃ cause the false triggering directly?

2. If they keep this LM293 under 90℃, what kind of damage to happen to this chip?

James

over 5 years ago

0 kai klaas69 over 5 years ago

Guru 140200 points

Hi James,

can you post a schematic?

Kai

0 James Zhan over 5 years ago in reply to kai klaas69

TI__Expert 4365 points

Hi Kai,

Are you a TI employee? This is a schematic from customer.

0 James Zhan over 5 years ago in reply to kai klaas69

TI__Expert 4365 points

Hi Kai,

What's the failure mode if the temperature is 90℃ ?

If the common voltage is 3.3V and power supply is also 3.3V, will this damage to the IC?

0 kai klaas69 over 5 years ago in reply to James Zhan

Guru 140200 points

Hi James,

no, I'm not an TI employee. I'm here for fun... :-)

The LM293 is only specified for the temperature range of -25° to 85°C. So, you can imagine what an TI employee will answer? Don't use the LM293 at 90°C!

What you have highlighted in red, is this an additional question?

Kai

0 Paul Grohe over 5 years ago in reply to James Zhan

TI__Mastermind 49856 points

Hi James,

Kai is correct. +90C is outside the +85°C specified range. They should be using the LM2903, which is specified to 125°C.

What is the supply voltage? Input voltages and ranges? Any scope photos of the "spurious triggering"?

Do all boards do it? Or just a few?

The wording you highlighted is expected behavior but should not be relied upon.

If you do not want to post schematics publicly, you can send it to me internally.

Amplifiers

Amplifiers forum

LM293: OverCurrent Dection Spurious Triggering