| ??? 08/26/05 08:20 Read: times |
#100121 - 8051 is open drain ! Responding to: ???'s previous message |
To drive a transistor, put the base direct on the 8051 port pin and a resistor from base to VCC.
Especially for LED multiplexing this works better, because the open drain output can strong discharge the Miller-capacity of the transistor (fast switch off). With only a resistor in series to the base, the weak discharging of the Miller-capacity may cause shadow segments on the next digit on higher multiplex frequency. Peter |
| 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 |