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TMS570LS3137 N2HET drive capability

yong zhang2
Expert 1305 points
Other Parts Discussed in Thread: HALCOGEN, TMS570LS3137

Hi,

I checked the technical reference manual of the n2het module, it says it can be used as the general purpose IO port, I want to know the drive capabilty of the n2het pins. Is it the same with the GIO? 

Regards,

yong

  • 0
    TI__Mastermind 22375 points

    Yong,

    Yes, the GIO programer's model for N2HET is the same as GPIO block.

    If you use Halcogen, the GIO APIs can be use to drive, configure and read N2HET pins (When not used as timer pin).

    Please let me know if you need more detail.

  • 0 in reply to Jean-Marc Mifsud
    Expert 1305 points

    Maybe I didn't make a clear expression. The drive capability means that the number of LED the pin can drive. If you use just one pin to drive many LEDs, what's the maximum number of the LEDs without any amplifier? And, every pin of the N2HET and the GIO has the same drive capability?

    Regards,

    yong 

  • 0 in reply to yong zhang2
    TI__Guru 68920 points

    Yong,

    Basically then you are asking how much current each pin will source or sink.   Then depending on the amount of current your LED needs you can figure our the answer to your question. (will vary depending on the type of LED you are talking about).

    You can find this information in recommended operating conditions section of the datasheet.   For example, for the TMS570LS3137 the datasheet has the information in Table 3.6 and Table 3.7 on page 41.   We give two points for I/V - one at no current and one at rated current, see the specs for VOH, VOL and the conditions list the currents at each point.   The max current IOLmax or IOHmax depends on the pin because some pins have stronger buffers.   The pin/buffer maping is given in Table 3.6.

    For LEDs you probably don't care about logic levels and the IO can sink/source more current if you allow it to go above VOL or below VOH but we don't have any curves in the datasheet giving this information.  There are some IBIS models on the processor wiki which could give an idea of this relationship at points in between but I don't think TMS570LS3137 IBIS are posted yet.

    You also need to consider the additional power dissipation due to the LED current and the voltage drop in the IOs you are using.   This could be significant if you have many LEDs.\

    Best Regards,

    Anthony