![](/images/new-backgrounds/1105276/10527671x1.webp)
Philips Semiconductors | User’s Manual - Preliminary - | |
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I/O PORTS | P89LPC906/907/908 |
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The third pullup is referred to as the "strong" pullup. This pullup is used to speed up
The
Although the P89LPC906/907/908 is a 3V device the pins are
A
VDD | VDD | VDD |
port latch data![](/images/new-backgrounds/1105276/10527671xi2.webp)
![](/images/new-backgrounds/1105276/10527671xi3.webp)
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| clock delay |
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| strong |
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| very |
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| weak | |||||
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input data
glitch rejection
Figure 4-1: Quasi-Bidirectional Output
OPEN DRAIN OUTPUT CONFIGURATION
The open drain output configuration turns off all pullups and only drives the pulldown transistor of the port pin 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 pullup, typically a resistor tied to VDD. The pulldown for this mode is the same as for the
The open drain port configuration is shown in Figure
An open drain port pin has a
port latch data
input data
port |
pin |
glitch rejection
Figure 4-2: Open Drain Output
2003 Dec 8 | 36 |