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TMS320VC5416: DSP chip was easily damaged

Part Number: TMS320VC5416

Hi there, we have used TMS320VC5416 BGA version for many years.   But sometimes we found it is easy broken for no reason.  So we suspect the design schematics issue.  There are many unused pins are not connected.   Whether these pins need to connect a resistor to ground or Vcc?  Attached schematics diagram.

  • The team is notified. They will post their feedback directly here.

    BR
    Tsvetolin Shulev
  • Hi Ken,

    It is best to control the state of the pins.
    Configure as many unused signals as outputs as you can - for example HPI Data Pins as General-Purpose I/O (GPIOCR register). McBSP also has a general purpos I/O mode.

    Can they measurable current flow into the device before damage? Check all voltage rails.
    After damage is one of the voltage rails shorted to GND or failing to reach its normal voltage?
    It would be good to find out if it is the DVDD rail or CVDD rail that fails.
    Is there any visible defect? Do any components or the device get hot or produce smoke?

    Floating inputs should be avoided. They can consume high amounts of current as the high impedance input is unknown and can oscillate between the threshold region of the CMOS IO. When the IO input is between the VIL and VIH, both gates are open and current flows through to GND.

    I recommend the customer search through Table 2-2. Signal Descriptions in the datasheet (www.ti.com/.../tms320vc5416.pdf) looking at the I/O column to see if the pin is an input, and then to check if that pin is floating.
    Just briefly glancing at the schematic, I see a few floating input pins like INT0/1/2.

    Some pins like HPIENA, HPI16, TRST have internal pull-downs that will keep the input controlled at a low state, preventing oscillation and current flow from a floating input. Newer processors int he C5x family have more of these internal pull-resistors to prevent the need for external termination. Otherwise, external termination is required on these inputs.

    To furhter prevent current flow, best practices should be followed. For example, it is better to place the LED between power and the device pin so the pin sinks current. If you source current from the pin (like D19 in the schematic), then the power must come from the device IO rail, which can draw more current than allowed by the IO. Table 5.2 Recommended Operating Conditions specifies the maximum output current for each pin (8 mA, excluding transients)

    The customer can compare schematics with the C5416 DSK: c5000.spectrumdigital.com/.../dsk5416_techref.pdf
    The C5416 DSK does use most of the device pins and also has lots of pull resistors...

    Hope this helps,
    Mark