J
Jon Slaughter
- Jan 1, 1970
- 0
http://focus.ti.com/lit/ds/symlink/tlc5947.pdf
This devices uses a resistor to set the constant current value. I am using
up to 24 of these things all tied together. I'd like to have one common
reference for all. (to be controlled by a pot to set the maximum current for
a dimming effect)
Ultimately what would be nice is if I could just tie them all to the same
resistor but I do not know if this will work? Maybe i'd have to use 24x the
resistance? I imagine they simply measure the current going through the
resistor and use that as the current(maybe current mirrors?)
I'm not sure though if this would be a valid method though? It definitely
would solve my problem though.
I believe the formula for setting the current is
I = 41*1.20 = 49.2/R_IREF as it shows on page 4.
so I'd just have to increase R_IREF by 24x(48k should get 24.5mA per IC).
Anyone see any problems doing it this way? (ultimately I probably will use
an active resistor so I can control it digitally)
This devices uses a resistor to set the constant current value. I am using
up to 24 of these things all tied together. I'd like to have one common
reference for all. (to be controlled by a pot to set the maximum current for
a dimming effect)
Ultimately what would be nice is if I could just tie them all to the same
resistor but I do not know if this will work? Maybe i'd have to use 24x the
resistance? I imagine they simply measure the current going through the
resistor and use that as the current(maybe current mirrors?)
I'm not sure though if this would be a valid method though? It definitely
would solve my problem though.
I believe the formula for setting the current is
I = 41*1.20 = 49.2/R_IREF as it shows on page 4.
so I'd just have to increase R_IREF by 24x(48k should get 24.5mA per IC).
Anyone see any problems doing it this way? (ultimately I probably will use
an active resistor so I can control it digitally)