10.1.2 Open-Drain Output
The open-drain output configuration turns off all pull-ups and only drives the pull-down transistor of the port pin
when the port register contains a logic “0”. To use this configuration in application, a port pin must have an
external pull-up, typically a resistor tied to VDD. The pull-down for this mode is the same as for the quasi-
bidirectional mode. In addition, the input path of the port pin in this configuration is also the same as quasi-
bidirectional mode.
The open-drain port configuration is shown in Figure 10-2. An open drain port pin also has a Schmitt-triggered
input for noise suppression.
Figure 10-2. Open-Drain Output
10.1.3 Input-Only (High Impedance Input)
The input-only configuration is a Schmitt-triggered input without any pull-up resistors on the pin, as shown in
Figure 10-3.
Figure 10-3. Input-Only
10.1.4 Push-Pull Output
The push-pull output configuration has the same pull-down structure as both the open-drain and the quasi-
bidirectional output modes, but provides a continuous strong pull-up when the port register contains a logic “1”.
The push-pull mode may be used when more source current is needed from a port output. In addition, the input
path of the port pin in this configuration is also the same as quasi-bidirectional mode.
The push-pull port configuration is shown in Figure 10-4. A push-pull port pin also has a Schmitt-triggered input
for noise suppression.
Figure 10-4. Push-Pull Output
MEGAWIN
MPC82G516A Data Sheet
38
MEGAWIN [ MEGAWIN TECHNOLOGY CO., LTD ]
