TLC5971 min PWM pulse width

I am having trouble finding the minimum pulse width for the TLC5971.  I see that it has 65536 pwm steps but can't seem to find the min pulse width.  Can anyone out there help with that?

Thank you,

Frank

  • Hello Frank,

    The minimum theoretical pulse width is one pulse out of 65536 pulses. Dependent on the selection of the GS clock (internal or external), this minimum time is 1 SCKI pulse or 1 pulse of the internal clock.

    The internal clock has typically 10MHz (8MHz to 12MHz) and with the maximum value selected, this is 1/12MHz = 83.3ns.

    The maximum speed of the external clock is 20MHz, then the minimum on-time is 1/20MHz = 50ns.

    The typical rise time  of the outputs is 5ns and the typical fall time is 15ns, see datasheet page 6.

    Best regards,
    Brigitte

  • In reply to Brigitte:

    Hi Brigitte!

    You told the minium pulse width is 50ns (=20 MHz)

    So does that mean that the RGB- LEDs generally flash with a frequency of 12E6/65536 = 305 Hz?

    It seems that this IC is not suitable for RGB-LED propeller designs. :-( Or am i wrong here?

    What about the other TI LED-PWM drivers? Does one of them give a much higher output frequency?

    If not, do have any suggestion for me which LED driver IC to use for a RGB-LED propeller display?

    With regards,
    Diethart