SAB80C517-M16 SIEMENS [Siemens Semiconductor Group], SAB80C517-M16 Datasheet - Page 42

• Manufacturer Part Number: SAB80C517-M16
• Description: 8-Bit CMOS Single-Chip Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Figure 7-3
Output Driver Circiut of Ports 1 through 6
The described activating and deactivating of the four different transistors translates into four states
the pins can be:
Semiconductor Group
– The pullup FET p2 is of p-channel type. lt is always activated when a "1" is in the port latch,
– The pullup FET p3 is of p-channel type. lt is only activated if the voltage at the port pin is
– input low state (IL), p2 active only
– input high state (IH) = steady output high state (SOH), p2 and p3 active
– forced output high state (FOH), p1, p2 and p3 active
– output low state (OL), n1 active
thus providing the logic high output level. This pullup FET sources a much lower current than
p1; therefore the pin may also be tied to ground, e.g. when used as input with logic low input
level.
higher than approximately 1.0 to 1.5 V. This provides an additional pullup current if a logic high
level shall be output at the pin (and the voltage is not forced lower than approximately 1.0 to
1.5 V). However, this transistor is turned off if the pin is driven to a logic low level, e.g. when
used as input. In this configuration only the weak pullup FET p2 is active, which sources the
current
Thus, an additional power consumption can be avoided if port pins are used as inputs with a
low level applied. However, the driving cabability is stronger if a logic high level is output.
I
IL
. lf, in addition, the pullup FET p3 is activated, a higher current can be sourced (
43
On-Chip Peripheral Components
I
TL
).