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DDC316: RANGE bit register settings during different test mode

Vincent Siah
Prodigy 20 points
Part Number: DDC316

Hi,

When the ADC chip is set into Test Mode 3 (TM[1:0] 11),  the RANGE bit settings can be changed without any problem. When a new conversion is occurred after changing the settings of RANGE bit, the output with the new RANGE settings is shown.

However it is not the same when the ADC is operated in normal mode (TM[1:0] 00).
During this mode, after changing the RANGE settings of the ADC from one settings to another (For example from 00 to 11), and a new conversion occurs, the ADC output still gives the range settings of 00 instead of 11.

While operating the ADC in normal mode, there is an fixed amount of charge dumped into the integrator externally.

I would like to know if there is anything that I have missed out anything that is required to do in order to change the RANGE settings during normal mode. Thank you very much.

Best Regards,

Vincent Siah

  • 0
    TI__Genius 11550 points

    Hi Vincent,

    Please refer to the section "Writing and Reading of the Configuration Register" on page 17 and Figure 2 for the sequence of how to write and read from the device configuration register. You can write to the device configuration register and read back the new configuration register on DOUT1. From the readback data, you can first verify that you have the correct TM and RANGE setting after writing the configuration register.

    Are you using the readback configuration register to determine the RANGE setting is incorrect or by looking at the DDC data output?

    The Test Mode (TM) function allows the user to verify the DD316 noise by changing how the input is connected to the integrator. For Test Mode 1, 2 and 3, the external source will be disconnected from the DDC316 integrator. These test modes allow the DDC316 noise to be evaluated without any external input source influence. The TM and RANGE setting are independent of each other so you should be able to change both the RANGE and TM setting to what you need.

    Please let me know if you need further help. Thanks. 

    -TC

  • 0 in reply to TCT
    Prodigy 20 points

    Hi TC,

    Thank you very much for the response, but turns out that the chip is malfunctioned: The particular channel for the conversion during the test did not work.

    Once I've changed to other channel the output came out as what I've expected.

    Thank you very much.

    Best Regards

    Vincent