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SN65LBC176: SN65LBC176D can be replaced with SN65LBC176AMDREP?

Yoshikazu Kawasaki
Expert 1051 points

Part Number: SN65LBC176

Hello,

We have delivery issue at a customer on SN65LBC176D, so we'd like to ask them to use SN65LBC176AMDREP.  If I look at both datasheets, I found a strange data at recommended operating conditions on SN65LBC176 other than the operating temperature range which was expected.  The strange data was IOH at receiver which was -400uA(min) whereas it was -8mA(min) on SN65LBC176AMDREP.  Would you please let me confirm if the datasheet of SN65LBC176 is correct?  Even if it is correct, the IOH at receiver on SN65LBC176AMDREP has higher one than SN65LBC176D, so SN65LBC176D can be replaced with SN65LBC176AMDREP in terms of IOH.  Am I correct?

However I see more differences on other items between those devices like |VOD| at RL=54Ohm, 1,1V(min) on SN565LBC176D but 0.9V(min) on SN65LBC176AMDREP.  It means even the receiver device from the SN65LBC176D works, it may not work from the output of SN65LBC176AMDREP, so SN65LBC176D can not be replaced with SN65LBS176AMDREP from the datasheet.  There are more differences, so My customer has to check carefully if SN65LBC176D can be replaced with SN65LBS176AMDREP.  Am I correct?

Best Regards,

Yoshikazu Kawasaki

  • 0
    TI__Guru 54042 points

    Hi Yoshikazu,

    Datasheet is correct.

    In terms of IOH - yes it can; the output current tested at for VOH on the EP device is minimum of 4V while the minimum on the "D" device is 2.7V with less output current - so if the input receiving this voltage can handle 5V signals than it shouldn't be an issue on that regard.

    So I am checking with my internal team to see if the devices mainly differ in spec's due to the different temperature range or if it due to a difference in the design. Since many specifications degrade with temperature and with the extended temperature range of the device it is possible that the EP device will act more like the "D" device when operated in the "D" devices range. There is a holiday on Monday here so I may not be able to get the information until next week. However the minimum/maximum specs on the device really refer to the max temperature or min temperature environments - which if attempting to replace the "D" device means that you shouldn't see the minimums or maximums as spec'd in the EP device.

    If you have any other questions in the mean time as I am gathering information from my internal team please let me know!

    Best,

    Parker Dodson

  • 0 in reply to Parker Dodson
    Expert 1051 points

    Hello Parker-san,

    Thank you very much for your comments.

    I understand what you meant.  Would you please tell me the status from your internal team?  May I tell my customer that AMDREP device works as if it is D device in the temperature range of -40degC ~ 85degC, so AMDREP device is drop-in replacement?

    Best Regards,

    Yoshikazu Kawasaki

  • 0 in reply to Yoshikazu Kawasaki
    TI__Guru 54042 points

    Hi Yoshikazu-san,

    I am sorry for the delay - I am still looking into the issue. This data due to its age and being an EP device has its information spread around. i am currently working with our internal team to find it - and I will update you as soon as I have information. I am not confident that they are same die due to a few of the spec differences not necessarily matching what you would expect if the parts where just validated at different temperature ranges. I am actively trying to confirm this or not.

    Best,

    Parker Dodson

  • 0 in reply to Parker Dodson
    Expert 1051 points

    Hello Parker-san,

    Would you please tell me the current status?

    I don't want you and your team to sped on this topic that much, so shall I tell my customer that AMDREP device could work as D device, but it's not guaranteed?

    Best Regards,

    Yoshikazu Kawasaki

  • +1 in reply to Yoshikazu Kawasaki
    TI__Guru 54042 points

    Hi Yoshikazu-san,

    I think that may be best - I am having a very hard time finding the die information on the EP devices - they have changed groups a few times so data is not easy to find. I really apologize for the issue here. 

    That being said - I am fairly confident its not the same die - the switching characteristics of the device do not line up with the difference in temperature testing. I.e. the changes of the timing parameters between devices doesn't make sense if the only difference was different temperature ranges. So in general they should be very similar but some of the specs may differ slightly. 

    I think using the EP device should be fine - but it may not be 100% identical. 

    Is there anything that the customer is concerned with the EP device - or do you have a schematic of the RS-485 bus - as that will help me determine how much of an issue anything will cause - however I don't think it would be too great of an issue.

    Please let me know!

    Best,

    Parker Dodson

  • 0 in reply to Parker Dodson
    Expert 1051 points

    Hello Parker-san,

    Thank you very much for spending a lot of time on this topic.  I'll tell my customer that AMDREP device may work as D device, but please check carefully on their system because some of the specs are slightly different.

    Best Regards,

    Yoshikazu Kawasaki