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Original question:

DS90LV049H: DS90LV049HMTX/NOPB

DS90LV049H: DS90LV049HMTX/NOPB

Yazharasan m
Prodigy 45 points
Part Number: DS90LV049H


Tool/software:

Hi ,

Hope you are doing good!

With the reference to my previous inquiry, would you please confirm my below queries!

1) Our existing IC's "FIN1049MTCX" Typical Differential input threshold is "0" and your IC's "DS90LV049HMTX/NOPB" Typical Differential input threshold is "-15". Would you please confirm what happen if the switching between -15 to 0 in IC "DS90LV049HMTX/NOPB"? Does this cause any impact to the function? According to our existing IC switching will happen only at 0.

2) Would you please let us know the relation between these two tables (Below)?

  

Thanks in advance.

Regard,

Yazh

  • 0
    Guru 318230 points

    1. A differential input, DC voltage of 0 V or −15 mV does not happen during normal operation; the LVDS driver will always force a voltage of more than +100 mV or −100 mV. During switching, the signal edges are so fast that the difference between 0 V and −15 mV does not matter. If the driver is powered down or disconnected, then the receiver's input pins are shorted through the termination resistor, and the voltage is 0 V; in that case, the output of the FIN1049 is random and might even oscillate, while the DS90LV049H is guaranteed to output a fixed value.

    2. The LVDS specification requires thresholds of +100 mV or −100 mV; this is shown in table 2. The DS90LV049H actually has better thresholds, as shown in the electrical characteristics table; they are fully compatible with all LVDS transmitters.

  • 0 in reply to Clemens Ladisch
    Prodigy 45 points

    Thanks for the reply.

    I have another question regarding the Full Fail-Safe OPEN/SHORT or Terminated condition. Do we need any additional circuitry for this, or is it included in the internal circuit? Also, does the following table come by default with the TIA/EIA-644-A LVDS Standard? This is not mentioned in our existing part's datasheet, although it references this standard.

  • 0 in reply to Yazharasan m
    Guru 318230 points

    The LVDS standard does not define fail-safe behaviour.

    No additional circuitry is neccesary. "Open" means that the input pins are not connected to anything; "terminated" means that the pins are connected with about 100 Ω.

  • 0 in reply to Yazharasan m
    TI__Expert 3170 points

    Hi Yazharasan,

    Clemens is correct. Failsafe biasing is a built in feature of this device that ensures a defined output value in the case of open/shorted receiver inputs. It is not something specified by the LVDS standard.

    Regards,

    Jack