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TMS320F28035: On-Chip Comparator Response-time/Delay-time.. Comparator-input (from device-input pin) to Comparator-output (to device-output pin)..

Newman
Expert 6015 points

Part Number: TMS320F28035

Hi Team C2K,

The F28035 datasheet (http://www.ti.com/lit/ds/symlink/tms320f28035.pdf ) specs "Comparator response time to PWM Trip Zone (Async).. 30nSec  Typical". 

But.. what is the specified(?) delay from Comparator-input (say tripped on a GPIO-input pin) to comparator-output.. when the comparator-output is connected to a GPIO-output/device pin? 

My customer has "..been running some tests and measuring response times of 275nS to 600 nS depending on how hard I am driving the comparator input (ie. How much over-drive above the threshold.)."

Thanks, Merril

  • 0
    TI__Guru 62975 points

    Merril,

    The pin-to-pin time is expected to be equivalent to the published response time.

    I recommend starting with a step input and with hysteresis disabled. This should produce a clean response time of around 30ns. If not, try another device. If the measured response times are consistent between devices, there may be device settings that are contributing delay to the response time.

    Comparator response times are difficult to measure precisely with slower slew rates because DC errors from the internal comparator will look like response time delays when observed externally. Hysteresis feedback will also introduce DC offset to the input signal.

    -Tommy