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TLC5628: About how work.

Part Number: TLC5628

Dear.

I need to make controls for a project and would like to use a DAC, but I've never worked with this device.
I have a project in which 7 LEDs are pulsed using 7 TTL signals coming from an Arduino. However, this array of LEDs are not pulsed all together and not one by one. They are pulsed in various combinations in which is not a sequential sequence. For example: in some moment the LEDs 1, 2, 3 and 5 are pulsed. At another moment the LEDs 1, 4, 5 and 6 are pulsed. Another question is, I need to control the current passing through each one LED to control its luminous intensity. Each LED is connected in a circuit switched by a transistor where an Arduino port opens and closes that transistor with a signal at the base.
So I think a DAC could help me do this intensity control of each LED by controlling the voltage applied to the base of the transistor. This voltage would be modulated through an output of the DAC which is controlled by the Arduino.
So I have some doubts about the operation of the TLC5628 DAC. First I would like to know if it is possible to simultaneously use more than one output of this DAC (TLC5628) so that each DAC output has its own voltage level? Also, is it possible to use a combination of outputs of this DAC in any combination that I desire?

  • Hi Eduardo,

    Yes, you can use each channel individually. Each channel has its own address, so you can write unique data to all the DAC individually, or just to the subset you want to change.

    Keep in mind that this DAC has a specified source current of 2mA minimum, so they may not source more than that.

    Thanks!
    Paul
  • Today I do the following: Each of the 7 LEDs is associated with an Arduino TTL port. I only turn on the arduino's ports that I want to power the desired LEDs while others remain off. After a certain time all the ports are turned off and thus a pulse of a combination of LEDs has been realized. I change the combination of LEDs and repeat the operation.

    So, using the DAC TLC5628, I could work this way: I write the words to load each of the DAC outputs where some outputs will have values between 0 and 5V (turn on) and others GND values (turn off). After loaded all the outputs, I activate it to release the signal. I then rewrite the GND value on all outputs and release those values and thus a pulse of a desired combination of LEDs is completed. Am I right?

    Regarding the drained current issue, each LED is mounted with a transistor so that the TTL signal coming from the Arduino / DAC is connected to the base of that transistor precisely so that too much current is not drained.

  • Yes, I think that should work.
  • Hi Eduardo,

    Please mark 'This Resolved My Issue' if you have no more questions in regards to this issue.

    Thanks!
    Paul