TTL System IO - IO1...IO4
There are four digital non-isolated input/output ports in both external and internal system connector. The ports are named, IO1, IO2, IO3 and IO4.
The port is a singled-ended I/O port. The "warm wire" of the transmission line carrying the control signal has to be connected on the IOi pin and the "cold wire" of the transmission line has to be connected on any of the GND pins of the system connector.
TTL System IO
The port is configured as an input during the board initialization phase. The port is also protected against electrostatic discharges and is equipped with a HF noise filter.
Behavior
- When configured as input, it behaves like a 5 volt tolerant TTL compatible input; a 4K7 pull-up to +5V ensure logic '1' when left unconnected.
- When configured as output, it behaves like a powerful TTL driver capable to supply large currents.
DC Characteristics
Inputs - DC characteristics |
Min |
Typ. |
Max |
Units |
Input voltage range |
0 |
|
5 |
V |
Logic-0 input level |
|
|
0.8 |
V |
Logic-1 input level |
2.0 |
|
|
V |
input impedance - Pull-up resistor |
|
4.7 |
|
kΩ |
Outputs - DC characteristics |
Min |
Typ. |
Max |
Units |
Output voltage range |
0 |
|
5 |
V |
Logic-0 output level @IoI = 8 mA |
|
|
0.4 |
V |
Logic-0 output level @IoI = 16 mA |
|
|
0.8 |
V |
Logic-1 output level @IoI = -3 mA |
3.0 |
|
|
V |
Logic-1 output level @IoI = -24 mA |
1.5 |
|
|
V |