TPS1HB08-Q1: SNS output to indicate system faults

Hey, 

The above measurements were taken during a fault to determine ISNSFH level? In addition how is this being measured? The operating voltage conditions should be measured with respect to device GND when determining voltage level. Do you have a schematic to show this application? What is being used to load this DUT?

BR, 

Alan 

Hi Alan,

Yes, both measurements were taken during a fault. We made an Open-load situation to test the fault indication function.

The refernce GND is the same. You could refer to the schematic below.

There is a inductive load(max 14A,typcal 6A) like a relay or something, however because it's open, so it may not be related to the test.

Hey, 

I will look into this and get back to you by 5/8

BR, 

Alan

Hey, 

Speaking with my team here it does look like the Isnsfh current source could not supply the same current at low voltage. I will work with design to see if there is a range here that can be used. I will update this thread when I have more information.

BR, 

Alan

Hi Alan，

   Is there any progress?

Hey, 

I am sorry for the delay, I am working with design to determine the SNS architecture to determine what is expected at a lower VBB. 

BR, 

Alan

Hi,

We alright tried a lower rsns, Vsns was higher even we didn't use as low as 800ohm.

But lower Rsns can not take advantage of the ADC full-scale, even  your datasheet recomends a higher one. So we don't really want to change it.

Could you explain how this problem happened? So that we can discuss if there is a good solution.

Hey, 

Have you tried 800ohm?

At low VBB such as 6v this is usually a transient condition. How long are you expecting to be at this voltage? With a nominal of 12v even in a cold crank scenario the voltage will be ~9V. 

BR, 

Alan

Hi,

No, as I said before I did not think a lower resistor is a good solution.

Customers want to keep the diagnostic function at low voltage. So it's a long time.

Hey, 

Unfortunately at low VBB for an extended amount of time will be a limitation to the device. The recommended solution from design would be lowering the RSNS value to about 800ohm. 

BR, 

Alan