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SMV320C6727B-SP: ESD, I/O Pins, and Emulation Signals

Part Number: SMV320C6727B-SP

Team,

  1. What is the ESD rating via the human body model? ESD information is not provided in the datasheet.
  2. If it is possible, what is the peak power or peak energy that any I/O pin can withstand during a transient event (i.e. lightning @ 1000us).
  3. The absolute maximum rating for any I/O pin is -0.3V to 0.5V assuming no power. Is this rating only applies during steady state condition? What about during transient events?
  4. What is the overall ON and OFF resistances on each I/O pins?
  5. From the application note (SPRAA87A), on section 4.1-Design Checklist, it appears that the EMU signals can work as unidirectional with a slow baud rate due to only one mode (Emulation/Normal Mode). However, the datasheet specified the opposite for this emulation signals. Are these emulation signals bidirectional with high baud rate (MHz range)?

Thank you.

  • Brad,
    1) This is specified as class 2 for HBM ESD. This is the older methodology, indicating that it passes 2000, but fails 4000V.
    2) We do not specify peak energy that an IO or ESD cell can withstand, other that what is specified for the ESD conditions.
    3) These are absolute specs, independent of static or transient conditions.
    4) We do not specify this. However, depending on the IO, an estimate of the output resistance can be made by looking at the IOH/IOL specs and min/max VOH/VOL values. Similarly, and input impedance can be estimated from worst case leakage specifications.
    5) From the datasheet, the EMU signals are shown as IO. I am not sure I understand your question.

    Regards,
    Wade
  • Hi Wade,
    Follow-up questions about the EMU0 and EMU1 signals: Although the ‘6727 datasheet lists EMU0&1 as I/O signals, other TI documentation seems to indicate that these signals are actually always inputs, at least specifically for the ‘6727. For example, the “TMS320C672x Hardware Designer’s Resource Guide” (SPRAA87A), on section 4.1-Design Checklist, it appears that these EMU signals are used only as inputs, to change between boundary scan and normal operating mode.

    However, other documentation seems to disagree. We are using the XDS510 emulation pod (from Spectrum Digital), and the user’s guide for the pod (XDS510 USB JTAG Emulator Technical Reference (506175-0001 Rev. C, May 2005) has the following words (p. 3-7): “EMU0-1 are I/O pins on the target device, however, they are only inputs to the emulator. In general, these pins are used in multiprocessor systems to provide global run/stop operations.” The block diagram for the XDS510 (p. 3-4) shows the EMU pins as being I/Os, not just inputs. Apparently the EMU pins are used for debugging systems with multiple DSP processors?

    My questions:

    1. Our design uses only one ‘6727 DSP chip, so perhaps we don’t need to use the ‘6727 EMU0&1 pins?
    2. For our application, if we use the EMU pins, we have a requirement to protect those chip I/Os from transient pulses. What functionality would we lose if we connected the ‘6727 EMU0&1 pins only as buffered inputs to the DSP chip, not I/Os?
    3. If we need to connect the ‘6727 EMU inputs as I/Os to be compatible with the XDS510 emulator pod, can we use an RC filter to help provide transient protection to these inputs? The XDS510 users guide mentions (p. 3-7) that the EMU signals must have pullups to provide a risetime less than 10 usec, and so as long as our filter meets this criteria, would that work?
    4. If the EMU signals are driving out of the chip, how much capacitance can those signals drive and still meet the necessary rise and fall times?
    5. If the EMU signals are bidirectional, can we use a bidirectional buffer to protect these signals? How would we know when to configure the bidirectional buffer as an input driving the ‘6727 chip, and when to drive out to the emulator pod?

    Thank you.
  • 1) You do need the EMU0/1 signals.
    2) This application note answers most if not all of your questions. www.ti.com/.../getliterature.tsp

    Regards,
    Wade