danrogers
Member
Hi all. I am working on something that is really starting to frustrate me.
I have a Arduino hooked up running a TLC5940 works very nicely. I want to be able to use the PWM control of the TLC5940 to feed into the ADJ pins on the drivers, to allow me to dim them.
If I ground the ADJ pin on the drivers, the LED's go off as expected.
I currently have the following circuit hooked up, using a BC327.
It does work, but sending a write of 4095 to the TLC5940 should turn the lamp fully off but it does not. It seems that the transistor is not being driven hard enough? I have tried both a 10k (connected to 12v) and a 4.7k pulling up to 5v) but still the same results. I have also tried setting the TLC5940 to sink 10 & 20mA constant currents.
Also the PWM range does not seem sensible i.e. a write of anything <3500 appears to give no dimming effect, when approx 2000 should in theory be half brightness.
If anyone has some suggestions on how I can get this working I would be very appreciative
https://www.electro-tech-online.com/custompdfs/2013/01/ZXLD1360.pdf
https://www.electro-tech-online.com/custompdfs/2013/01/slvs515c.pdf
I have a Arduino hooked up running a TLC5940 works very nicely. I want to be able to use the PWM control of the TLC5940 to feed into the ADJ pins on the drivers, to allow me to dim them.
If I ground the ADJ pin on the drivers, the LED's go off as expected.
I currently have the following circuit hooked up, using a BC327.
It does work, but sending a write of 4095 to the TLC5940 should turn the lamp fully off but it does not. It seems that the transistor is not being driven hard enough? I have tried both a 10k (connected to 12v) and a 4.7k pulling up to 5v) but still the same results. I have also tried setting the TLC5940 to sink 10 & 20mA constant currents.
Also the PWM range does not seem sensible i.e. a write of anything <3500 appears to give no dimming effect, when approx 2000 should in theory be half brightness.
If anyone has some suggestions on how I can get this working I would be very appreciative
https://www.electro-tech-online.com/custompdfs/2013/01/ZXLD1360.pdf
https://www.electro-tech-online.com/custompdfs/2013/01/slvs515c.pdf