• State Resolved
  • Locked Locked
  • Replies 10 replies
  • Answers 1 answer
  • Subscribers 31 subscribers
  • Views 336 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TMS570LS3137: AC Timing Input / Output Conditions

Nilesh Khupase
Intellectual 480 points
Part Number: TMS570LS3137


Hello,

I need to know the AC Timings Input / Output Conditions (reference voltage levels, AC test load if any) for the SPI interface timings of the TMS570. Can you please let me know the same? 

Thanking you in advance.

  • 0
    TI__Guru**** 198766 points

    Hello,

    The voltage level should be the recommended operating voltage: 3.3V. The value of load capacitance used for the test is listed in Table 5-7. The drive strength of the output buffer is listed in Table 5-4. 

  • 0 in reply to QJ Wang
    Intellectual 480 points

    Hi,

    sorry I think I asked it in wrong way, I want to know the voltage thresholds taken into consideration for the measurement of timing parameters ( Of SPI) mentioned in the

    Table 7-24, 25 of the datasheet and also the AC test load if any applied during these parameter measurements.

    Thank you.

  • 0 in reply to Nilesh Khupase
    TI__Guru**** 198766 points

    Hello Nilesh,

    Nothing special. The signals input/output to/from this device should meet the operating conditions listed in Table 5-8. There is no 5V tolerate input pins except for ADC inputs when VCCAD=5V.

  • 0 in reply to QJ Wang
    Intellectual 480 points

    Hello QJ,

    Thanks for your reply. what I want to ask is voltage thresholds considered for the measurement of I/O timing parameters ( Of SPI interface of TMS570) by TI which are mentioned in the Tables 7-24, 7-25 of the datasheet and also the AC test load (other than CL) if any applied during these timing parameter measurements.

  • 0 in reply to Nilesh Khupase
    TI__Guru**** 198766 points

    Yes, the thresholds should be considered in the measurement. 

  • 0 in reply to QJ Wang
    Intellectual 480 points

    "Yes, the thresholds should be considered in the measurement" -  Thanks again for your reply. Yes I am asking the same what threshold levels should I take into consideration?

    And TI must have applied/done some load/ Test setup for these I/O timing measurements, I want to know that loading circuit as well. 

  • 0 in reply to Nilesh Khupase
    TI__Mastermind 49120 points

    The voltage thresholds for input signals are listed in the part's datasheet in the section titled "Input/Output Electrical Characteristics". These thresholds are compatible to TTL levels: 0.8V ViL(max) and 2.0V ViH(min). This table also describes the thresholds for output signals, compatible to CMOS output levels: VoL(max) of 0.2*VCCIO and VoH(min) of 0.8*VCCIO

    The typical tester measurement circuit looks like this. There may be some variations depending on the actual tester used.

  • 0 in reply to Sunil Oak
    Intellectual 480 points

    Hello Sunil,

    I need to clarify one thing, in the IBIS model of TMS570 for the I/O models some test load conditions have been mentioned. These are, 

    Vinl =  1.15                         
    Vinh =  1.55                         
    Cref =  15.0001pF                    
    Rref =  101.0000M                    
    Vref =  0V                           
    Vmeas =  1.65

    Are these timing test load values? Does it mean that Vinl, Vinh and Vmeas are actual Input/output voltage measurement points for the I/O timings of the ports which are mentioned in the TMS datasheet? If yes is it same over the entire operating voltage range of 2.97V to 3.63V?

  • 0 in reply to Nilesh Khupase
    TI__Mastermind 49120 points

    Hi Nilesh,

    Yes, the model uses these thresholds across the operating voltage range. These are typical values with a +/- range specified further in the model_spec.

  • 0 in reply to Sunil Oak
    Intellectual 480 points

    Hello Sunil,

    Thank you very much for your reply. I wanted to know this only  - AC Timings Input / Output Conditions (reference voltage levels, AC test load if any) for TMS570.