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SN65HVD82 - Vout in case of IOL(output current Receiver)=15mA

Hirotaka Matsumoto
Guru 27525 points
Other Parts Discussed in Thread: SN65HVD82, SN74LVC1G125

Hi all,

Would you mind if we ask SN65HVD82?

<Question>
The data sheet shows  that the recommend value of IOL is 8mA.
Our customer request is  over 15mA load? So, is it avilable?
And then, with using IOL=15mA, how much is the value of Vout? 
(The data sheet only shows the value of IOL=8mA)

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Mastermind 28265 points

    Hello Matsumoto-san,

    the SN65HVD82 maximum output is designed for connecting to UARTs and micro controller UART I/O with typical output currents of  less 1mA. The specified output current of 8mA is where the device is just within TTL spec. For higher output currents please use SN74LVC1G125 as output buffer.

    Regards, Thomas.

  • 0 in reply to Thomas Kugelstadt
    Guru 27525 points

    Hello Thomas San,

    We'd like to confirm about Iol.
    This Iol mentions pin No,1(R) of SN65HVD82, right?

    We need your help.

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Mastermind 28265 points

    yes it does, and if Iol increases to 15 mA then Vol is much higher than 0.4V.

    our receiver outputs are already much higher specified and more powerful than competition devices.

    future transceivers will have much less receiver output drive capability

    regards, Thomas

  • 0 in reply to Thomas Kugelstadt
    Guru 27525 points

    Hello Thomas san,

    You said that "and if Iol increases to 15 mA thVol is much higher than 0.4V.", if you have correct data in case of Iol=15mA, please let me know this.
    Otherwise, if you have approximate one(as like between 0.4V to 0.6V), please. 

    Kind regards,

    Hirotaka Matsumoto

     

  • 0 in reply to Hirotaka Matsumoto
    TI__Mastermind 28265 points

    I meant if an external current of 15mA is forced in the low output, then Vol will be much higher than 0.4V.

  • 0 in reply to Thomas Kugelstadt
    TI__Mastermind 21336 points

    Hi Matsumoto-san,

    For high currents like 15mA, I think the safer route is to place a buffer in between the output R pin and the whatever it is your customer is driving like Thomas suggested.

    With that being said, I went into the lab with one SN65HVD82 device to find the typical VOL with 8mA and 15mA at room temperature and nominal 5.0 volts. This is not a guarantee, just wanted to share a couple data points.

    The VOL at 8mA of current being sank by the R pin was 55.53mV. However, the VOL at 15mA of current was 101.53mV, and there looks to be a small amount of self-heating since this number continued to slowly rise as the device continued to sink 15mA (rose about 100mV over 5 minutes).

    In summary the device appears to be able to drive this amount of current, but since this was not characterized we cannot guarantee the performance.

    Thanks,

    John

  • 0 in reply to John Griffith
    Guru 27525 points

    Hello John san,

    Thank you for your reply.
    We have some confirmation and one question.

    <Confirmations & question>
    1. You don't have the characteristic diagram of “Receiver output current - Receiver output voltage”, do you?
    2. It is not a guarantee to load 15mA to R pin of SN65HVD82, right? Does it mean prohibition or recommendation?
    3. The VOL at 8mA of current being sank by the R pin was 55.53mV.The VOL at 15mA of current was 101.53mV.
        The data sheet shows that VOL typ is 0.2V at 8mA. So, which is correct?

    We need your help.

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Mastermind 21336 points

    Hi Matsumoto-san,

    1. You don't have the characteristic diagram of “Receiver output current - Receiver output voltage”, do you? We did not create a plot like this for the datasheet but here are 20 points I just took on the same device using a source meter.

    Current (mA) Voltage (mV)
    1 10.1
    2 16.5
    3 23.0
    4 29.5
    5 35.9
    6 42.4
    7 48.9
    8 55.4
    9 61.9
    10 68.5
    11 75.0
    12 81.5
    13 88.1
    14 94.7
    15 101.2
    16 107.8
    17 114.4
    18 121.0
    19 127.5
    20 134.3

    2. It is not a guarantee to load 15mA to R pin of SN65HVD82, right? Does it mean prohibition or recommendation? Since you are within the ABS MAX table, the device will not be damaged. But we are not guaranteeing the performance since we only characterize the device within the recommended operating conditions. Therefore, the numbers listed in the electrical parameters tables in the datasheet are not guaranteed outside the recommended operating conditions.
    3. The VOL at 8mA of current being sank by the R pin was 55.53mV.The VOL at 15mA of current was 101.53mV.
        The data sheet shows that VOL typ is 0.2V at 8mA. So, which is correct? The datasheet is a guarantee, what I shared is a single device. Treat it as a single data point.

    Thanks,

    John

  • 0 in reply to John Griffith
    Guru 27525 points

    Hello John san,

    Thank you for your reply!
    We treat these data as reference data.

    Kind regards,


    Hirotaka Matsumoto