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I2C DEFAULT SETTINGS FOR DS92LX1621 Serializer

Noble Narku-Tetteh
Prodigy 50 points
Other Parts Discussed in Thread: DS92LX1621, DS92LX1622

Hi All,

 I am a EE grad  student at Texas A&M majoring in Analog and Mixed Signal.

I am currently working on a PCB test board for a Time-to-Digital Converter. The Width of my output Digital word is 16 Bits. Due to the large amount data storage required and the limited number of oscilloscope channels available, I have opted to serialize the digital word and use 1 channel of the a high performance oscilloscope in our lab to be able to store all the data in the characterization test. Upon searching i decided on the DS92LX1621 serializer, which meets all the expected requirements. I want to find out a number of things about this part:

1. Is it possible to use this DS92LX1621 in the said configuration without the DS92LX1622 De-Serializer.

2. Are the default Register settings sufficient for the said purpose or do I need to wirte to the DS92LX1621 via the I2C interface  (SCL and SDA pins).

3. What should be the logic values for the following pins : MODE, PBD.

4. What should be the RID resistor value if i require it .

5. Do i need to use the GPIO Control interface (GPIO[0] and GPIO[1] pins).

Thank you.

Regards,

Noble Narku-Tetteh

  • 0
    Prodigy 50 points

    Hi All,

    I am wondering if i posted in the wrong forum, since nobody has responded yet. I hope my questions were clear enough. I would really appreciate a response to this thread at the nearest convenience. Thank you for your time.

    Regards,

    Noble Narku-Tetteh

  • 0 in reply to Noble Narku-Tetteh
    TI__Expert 7395 points

    Hi Noble,

    1 ) The DS92LX1621 needs to be paired with the DS92LX1622. Channel-Link III is a TI proprietary interface and will NOT interoperate with other vendor devices.

    2 ) Under default register settings the chipset will operate, however I2C access across the link is not available unless registers are programmed.

    3 ) The MODE, PBD pin logic levels are referenced to the VDDIO (1.8V or 3.3V) supply pin. The DC thresholds are specified on datasheet page 8 under LVCMOS DC SPECIFICATIONS 1.8V / 3.3V I/O.

    4 ) The RID sets one of the six physical device addresses based on the resistor network. See datasheet page 27 on Tables 3,4.

    5 ) GPIO[0] and GPIO[1] pins are optional and may be disconnected if not used. These GPIOs allow signals to be transmitted from Deserializer to Serializer.

    Dac Tran

    SVA APPS

  • 0 in reply to Dac Tran
    Prodigy 50 points

    Thank your Dac Team.

    1. So will the DS92LX1621 Serializer be able to serializer data unto a channel which goes to a scope. Or without the Deserializer it would be impossible to function. Id the Deserializer is required then for my intended set-up what would be the best way to proceed. As previously mentioned, i only want to serialize the data tot a scope for storage.

    2. The default registers should be satisfactory for the normal operation then.

    3. Sorry for the nature of the questions but can i tie RID to ground since i don't  require a Device ID for my application.

    Thank you for the quick reply.

    Regards,

    Noble

  • 0 in reply to Noble Narku-Tetteh
    Prodigy 50 points

    Dac Team.

    My intended setup is almost identical to the setup in Figure 9 of the Datatsheet of the DS92LX1621/22. The PCB traces are standard 50 Ohm traces leading to a side-mounted (horizaontal) SMA connectors. The Oscilloscope is a High performance oscilloscope with 50 Ohm differential termination, AC coupled. BW(max) of the scope is 23GHz.

    I wish to know if the Serializer will work fine in this setup.

    Thank you.

    Best Regards,

    Noble

  • 0 in reply to Noble Narku-Tetteh
    TI__Expert 7395 points

    Hi Noble,

    1 ) Yes, the DS92LX1621 serializer is able to function without a deserializer attached. Just set the 1621 mode pin 8 to H and apply a clock input to the PCLK pin. If you don’t provide a PCLK input, then device will run off the internal oscillator at 25MHz (700mbps linerate). You will be able to monitor the serialized data stream and eye diagram on setup as shown in Figure 9.

    2 ) Yes, device can operate in the normal mode with default registers.

    3 )  RID can be tied to ground. I2C control is optional if you don’t intend to use it.

    Dac Tran

    SVA APPS

  • 0 in reply to Dac Tran
    Prodigy 50 points

    Hi Dac Tran

    On page 25 of the DS92LX1621 Datasheet, indicates that the serialized data is 28-bit long and the "Data is randomized, balanced and scrambled". I want to know what this actually implies.

    As mentioned above in previous posts, i intend to store the data on an oscilloscope, and then post process it using matlab, due to the lack of 16 channel logic analyzer. Will I be able to deserialize the data in matlab? or the encoding and scrambling will not make this possible.

    Thank you for your time.

    regards,

    Noble Narku-Tetteh

  • 0 in reply to Noble Narku-Tetteh
    TI__Expert 7395 points

    Hi Noble,

    The serializer performs a parallel-to-serial conversion on the input data. Serialized data is internally encoded where by data is randomized, scrambled and DC balanced. You will NOT able to decode at the other end without a deserializer.

    Dac Tran

    SVA APPS