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SM320C32-EP Signal reflections causing upset

Hi Team,

Question regarding the SM320C32 (5V) DSP electrical operation.  

If the external data bus was rather long (6") and fans out to several components (5x) could the signal reflections from data bus write cycles cause any upset with the DSP?  

We are running tests and have found that a certain sequence of writes to an external parallel DAC on the data bus results in the DSP apparently hanging up.  One thought is the data bus reflections are generating currents in the DSP substrate.  

Has TI experienced this type of fault before ? or is it even plausible.

Thank you,


  • Jared,
    I am not aware of this type of failure or upset occurring on other uses of this device or other DSPs. However, most of the design ins of this device occurred a long time ago.

    Some comments:
    Has signal integrity been evaluated? Is there significant over/undershoot. Possibly termination would minimize SI issues.
    Is there any potential that there could be bus conflict at time of issue?
    Is there sufficient decoupling and power routing to device?
    An assessment of ground bounce can be made by probing a static low output near the bus (or a bus member that is static low ). The output will closely reflect the ground seen internal to device.
    Similarly, the noise on VDD during this time could show if there is adequate power/decoupling.