SAH-C515 SIEMENS [Siemens Semiconductor Group], SAH-C515 Datasheet - Page 55

• Manufacturer Part Number: SAH-C515
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

On-Chip Peripheral Components
C515
6.1.4 Port Loading and Interfacing
The output buffers of ports 1 to 5 can drive TTL inputs directly. The maximum port load which still
guarantees correct logic output levels can be be looked up in the DC characteristics in the Data
V
Sheet of the C515 or in chapter 10 of this User’s Manual. The corresponding parameters are
OL
V
and
.
OH
The same applies to port 0 output buffers. They do, however, require external pullups to drive
floating inputs, except when being used as the address/data bus.
When used as inputs it must be noted that the ports 1 to 5 are not floating but have internal pullup
transistors. The driving devices must be capable of sinking a sufficient current if a logic low level
I
I
shall be applied to the port pin (the parameters
and
in the DC characteristics specify these
TL
IL
currents). Port 0 as well as port 1 programmed to analog input function, however, have floating
inputs when used for digital input.
Semiconductor Group
6-12