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Semiconductor Group 5 - 1

On-Chip Peripheral Components

5 On-Chip Peripheral Components

5.1 Digital I/O Port Circuitry

To realize the Hardware Power Down Mode with floating Port pins in the SAB 80C517A/83C517A 5

the standard port structure used in the 8051 Family is modified (figure 5-1).

The FETs p4, p5 and n2 are added. During Hardware Power Down this FETs disconnect the port

pins from internal logic.

Figure 5-1

Port Structure

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Siemens EF 88H Series Manuale Utente Pagina 36