the failsafe function of the LVDS transmitter

[chang830]

Hi,
For the LVDS transceivers, it is known that a failsafe functioon is needed for receivers because it is the small siganl detector. But I have some puzzles on the transmitters, why it also need the input failsafe protection part, considreing the TTL/CMOS input?

Thanks in advance

 

[laglead]

I also know a LVDS transmitter. But I didn't find the failsafe function.
Can you tell me what is failsafe function? Its purpose and how it is realized.

thanks!

 

[ericzhang]

It is doubt that the failsafe function is at the receiver
side.

 

[husseinadel]

It is doubt that the failsafe function is at the receiver
side.

what is the failsafe function?!!!

 

[John Xu]

hi, deal above all,
Pls. see the attached files. This is the datasheet of a quad LVDS transmitter from National Semiconductor. It ha the failsafe function at in floating inputs. I guess, when the input pin is in float status, it acts like as an antenna, it will trigger the LVDS transmitters to malfunction, just like LVDS receivers.

PLs. correct me if i am wrong.

 

[ericzhang]

Fail-Safe specification
In an LVDS interface, the fail-safe specification forces the receiver to provide logic-high level under certain input conditions. The receiver will output a logic high when one of the following conditions is true:
• The driver is disconnected from the receiver or powered off while the receiver is still powered on.
• The two lines of the differential pair become shorted.
• The inputs of the receiver are left open.
This fail-safe mode prevents the receiver from providing invalid data because of unexpected voltages on inputs.

 

[husseinadel]

so,, in the LVDS transmitter for which it has CMOS input from inside the chip,,is it required this failsafe or not????

thanks