DS90LV804: Swap input signals for DS90LV804...

Peter Tseng

Mastermind 6540 points

Part Number: DS90LV804

Dear Sir,

Is it possible that customer tied input positive signal to LV804 IN- and negative signal to LV804 IN+ ?

over 8 years ago

0 Lee Sledjeski over 8 years ago

TI__Mastermind 43795 points

Yes, the device can work with the P/N inputs and outputs crossed. This is often done to improve routing on the PCB.

Regards,
Lee

0 Peter Tseng over 8 years ago in reply to Lee Sledjeski

Mastermind 6540 points

Hi Sir,

Thanks for your reply.

Based on above question, while the input signal swapped, how to add the external resistor for failsafe function?

What I mean is, should customer add the pull up resistor with positive signal or follow up with positive input pin of IC?

And what value of PU/PD resistors that customer need to add?

Thanks.

0 Lee Sledjeski over 8 years ago in reply to Peter Tseng

TI__Mastermind 43795 points

Hi Peter,

The input is symetrical so the PU/PD resistors can be added to produce either a logic "1" or logic "0" on the output.

Typically I recommend around 2.2K pull down and 4.7K pull up to give ~ 50mV of offset voltage at the input. Some systems with low speed signals can use lower value resistors for additional noise margin (1.2K PD and 2.2K PU).

Regards,

Lee

0 Peter Tseng over 8 years ago in reply to Lee Sledjeski

Mastermind 6540 points

Dear Sir,

Thanks reply for the question!

About the question 1, i cannot understand your point.

I will show you with picture below.

Which one is correct?

Thanks.

0 Lee Sledjeski over 8 years ago in reply to Peter Tseng

TI__Mastermind 43795 points

Hi Peter,

Either method will work. Choose the one which results in the desired output condition during a failsafe event.

Regards,

Lee

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DS90LV804: Swap input signals for DS90LV804...