| ??? 05/08/08 00:36 Read: times |
#154557 - How much current? Responding to: ???'s previous message |
If you have a 10K resistor in the common cathode, then in order to sink all 140 LEDs with, say 4 mA, which is pretty minimal, you would have to have a VERY high anode voltage, would you not?
What is missing is the required current per LED. If there are 20 of them per segment, he has to have enough current to drive seven times that in order to produce an 8. The cathode resistor must support that! In reality, the anodes should be driven with controlled current sources switched on or off with a BCD or HEX to 7-segment encoder, either hardware or firmware. RE |
| Topic | Author | Date |
| At89c52 port pin source | 01/01/70 00:00 | |
| ? | 01/01/70 00:00 | |
| ULN is negative logic. | 01/01/70 00:00 | |
| Level translator | 01/01/70 00:00 | |
| How much current? | 01/01/70 00:00 | |
Power cosumption | 01/01/70 00:00 |