PaulRB:
More than that. In your diagram above, you show 2 parallel groups each of 6 LEDs in series. I think 6 is probably too many. 5 might be ok. You can do this because your supply voltage, which could be as low as 12V, is still many times higher than the forward voltage of a single red led, which is normally around 2V. The total forward voltage of 5 LEDs is 10V, leaving 2V to be dropped by the series resistor (eg. 100R).
Got the point here.
PaulRB:
The important point is that the LEDs in series are not drawing 5 X 20mA, the same 20mA flows through all 5 LEDs. That means a single output of the tpic chip could support 7 parallel groups of 5 LEDs in series, 35 LEDs in total.
Sorry I didn't understand it. Are you are saying those 5 LEDs per series only consume a total of 20mA? How? Then if 35 LEDs for each pin, I will have 35 x 8 outputs = up to 280 LEDs per single tpic6b595?
PaulRB:
No, the max current for 74hc595 is 70mA total for 8 outputs and the max voltage is 5 or 6V, so not suitable at all.
Ohh.. Right, that current is way less than what I need.
BTW: I can only get tpic6b595/tpic6c595 through online stores in US/China which will either take few weeks to deliver or cost me a fortune for express shipping. Though, I believe the tpic are the perfect chips for my project and I can pay it if it's the only way to get my project done.. I really like tpic6b595 so far, but if there's an alternative way, please let me know too ..
EDIT: Will the tpic6b595 and tpic6c595 support multiple blinking LEDs? I am not only creating a brake light. They will be in "show mode" most of the time and only lights up all when the brake input is HIGH/LOW.