| ??? 08/24/05 10:29 Read: times |
#99958 - LED Responding to: ???'s previous message |
Alexander Koppe said:
i want to drive 4 LED´s (~25mA) with 4 portpins of a Atmel 8051. Do you mean 25mA per LED, or a total of 25mA for all four? Either way, you need to check the specific Atmel Datasheet for its individual port pin current ratings, and its "total device" current rating. my LED´s have one common vcc. Can somebody help me what I have to change in the circuit? For open-drain drivers (as in standard 8051 ports), one common Vcc pin is ideal. If the pin & device current ratings allow, you should just be able to connect direct to the port pin via a suitable series resistor: 
http://chaokhun.kmitl.ac.th/~kswichit/2051/basic/basic.htm |
| Topic | Author | Date |
| I need help with LED Driver | 01/01/70 00:00 | |
| LED | 01/01/70 00:00 | |
| LED | 01/01/70 00:00 | |
| use a LED driver | 01/01/70 00:00 | |
| 74LS drivers | 01/01/70 00:00 | |
| LED Driver - My Solution | 01/01/70 00:00 | |
| quite risky | 01/01/70 00:00 | |
| MCU-resistor-NPN | 01/01/70 00:00 | |
| 8051 is open drain ! | 01/01/70 00:00 | |
| not good idea | 01/01/70 00:00 | |
| totally wrong ! | 01/01/70 00:00 | |
| This I would take with a grain of salt. | 01/01/70 00:00 | |
| But nevertheless totally unsuited! | 01/01/70 00:00 | |
| Where in Atmel errata or other informati | 01/01/70 00:00 | |
| That's standard performance of quasi bi. | 01/01/70 00:00 | |
| Try This | 01/01/70 00:00 | |
updated | 01/01/70 00:00 |