When the CTRL voltage is less than 0.9 V (typ), the LEDs will shutdown to zero current. When the CTRL voltage is greater than about 2.6 V, full scale brightness is applied to the LED output.
why not look at the cat4101 - less additional hardware needed to accomplish same thing
Yes, that's it, Xenosaga. Word of caution though - while the datasheet states that 90K is the maximum recommended Rset value I believe that that translates to the datasheet's stated minimum 50ma of LED current (never fully off). The datasheet never fully answers that question and only shows current up to 35K (Fig. 7 pg. 3).
Hi Tristan,I made some related comments recently in a thread regarding the "always on" issue with the TLC5940 here: http://arduino.cc/forum/index.php/topic,144330.15.htmlThe PWM output on that chip can never be truly at 100% duty cycle, only slightly under. As youve figured out, the PWM is inverted due to the fact the chip is a current sink so the LEDs can never be fully turned off. If that is a manditory requirement to your project You'll need to modify your design. Four high level ideas I have off the top of my head are:1. You can have the microcontroller cut the power to the LEDs using a relay/switch of some kind.2. It should be possible to invert the 14 TLC5950 PWM signals using a transistor for each.3. You could implement LED drivers that use P-FETs to switch current.4. Do away with the TLC and Impliment a simpler design using a SoftPWM solution as I explain in the post I made in the thread linked above.
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