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ADC12DJ3200EVM: Query on dual channel and single channel mode

Thakur Rohit Singh
Prodigy 130 points
Part Number: ADC12DJ3200EVM
Other Parts Discussed in Thread: ADC12DJ3200

Hi team

I am looking to clearly understand the difference between 12bit, single channel, 8 lanes JMODE0 and 12-bit, dual channel 8 lanes JMODE2. As per the data sheet, Table 19 'L' and 'M' value for both modes are 4.

As per my understanding, in case of JMODE0, 12bit single channel ADC, to have 8 lanes interfacing with the upstream device (suppose FPGA), we need to have data from both channel A and channel B to have 4 lanes per convertor link. Whereas in case of JMODE2, 12 bit dual channel ADC, to have 8 lanes interfacing with upstream device, we can have data from one channel and routed to both the convertors through both the DDC.

Let me know if my understanding is correct with your explanation.

Regards

Rohit

  • 0
    TI__Mastermind 39050 points

    Hi Rohit,

    We are looking into this and will get back to you on Monday.

    Regards,

    Rob

  • 0
    TI__Mastermind 20541 points

    Hi Rohit,

    The ADC12DJ3200 can be used in single channel mode( sampling frequency is double of the device clock applied to the ADC). The analog input signal is only applied to single channel output data is interleaved and sent across 8 lanes.

    JMODE2 is dual channel mode( sampling frequency is same as device clock applied to the ADC) . The ADC act as dual channel ADC. and output data from ChA and ChB is sent across 8 lanes.

    If you want to DDC you will have to use a dual channel mode where decimation factor is greater than 1.

    Regards,

    Neeraj

  • 0 in reply to Neeraj Gill
    Prodigy 130 points

    Hi Neeraj

    Thank you for the response, much appreciated!

    Actually i was looking at section 7.4.3.2 of the ADC12DJ3200 data sheet where it says "When operating in dual-channel mode, the data from one channel can be routed to both DDC blocks by using DIG_BIND_A or DIG_BIND_B. This feature enables down-conversion of two separate captured bands from a single ADC channel". 

    How do we use Dual channel DDC for 8 lane configuration as above explanation says data from one channel can be routed to both DDC with DIG_BIND_A or DIG_BIND_B=0 and sent to the JESD links? The other channel will not be in use in this case.

    Regards

    Rohit

  • 0 in reply to Thakur Rohit Singh
    TI__Mastermind 20541 points

    Hi Rohit,

    Yes, you can power down the input channel which is not being used. For example if you are using CHA, you can power down channel B and route the data from CHA to the DDC of using dig_bind register. 

    In the above example you can program the register address 0x216 to value of 0x0 and use the second DDC to look at different frequency band. 

    Regards,

    Neeraj 

  • 0 in reply to Neeraj Gill
    Prodigy 130 points

    Hi Neeraj

    Thank you for the detailed info. Actually my doubt is that how this configuration is said to be dual channel when we are powering down the channel B in this case and using only channel A. In my understanding in case of dual channel mode, the inputs are applied to both channel A and channel B. Correct me if i am wrong.

    Regards

    Rohit

  • +1 in reply to Thakur Rohit Singh
    TI__Mastermind 20541 points

    Hi Rohit,

    The mode above is used when you want to look at two different frequency bands and only use single input and the two DDC blocks can be set to two different frequency bands. This mode let you save power by turning off un used input channel. 

    Regards,

    Neeraj 

  • 0 in reply to Neeraj Gill
    Prodigy 130 points

    thank you so much.