AT83C5103 datasheet(13/64 Pages) ATMEL

13 / 64 page

AT8xC5103

4134C–8051–09/04

Figure 3. Quasi-Bi-directional Output

Open Drain Output

Configuration

The open-drain output configuration turns off all pull-ups and only drives the pull-down

transistor of the port driver when the port latch contains a logic 0. To be used as a logic

output, a port configured in this manner must have an external pull-up, typically a resis-

tor tied to VDD. The pull-down for this mode is the same as for the quasi-bi-directional

mode. The open drain port configuration is shown in Figure 4.

Figure 4. Open Drain Output

Push-Pull Output

Configuration

The push-pull output configuration has the same pull-down structure as both the open

drain and the quasi-bi-directional output modes, but provides a continuous strong pull-

up when the port latch contains a logic 1. The push-pull mode may be used when more

source current is needed from a port output. The push-pull port configuration is shown in

Figure 5.

Figure 5. Push-pull Output

2 CPU

Input

Strong

Very

Weak

Clock Delay

Port latch

Data

Input

Port latch

Data

Input

Strong

Port Latch

Data

AT83C5103 Datasheet(PDF) 13 Page - ATMEL Corporation