SAB-C167SR-LM SIEMENS [Siemens Semiconductor Group], SAB-C167SR-LM Datasheet - Page 46

• Manufacturer Part Number: SAB-C167SR-LM
• Description: 16-Bit CMOS Single-Chip Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

AC Characteristics
Definition of Internal Timing
The internal operation of the C167SR is controlled by the internal CPU clock
CPU clock can trigger internal (e.g. pipeline) or external (e.g. bus cycles) operations.
The specification of the external timing (AC Characteristics) therefore depends on the time between
two consecutive edges of the CPU clock, called “TCL” (see figure below).
Figure 11
Generation Mechanisms for the CPU Clock
The CPU clock signal can be generated via different mechanisms. The duration of TCLs and their
variation (and also the derived external timing) depends on the used mechanism to generate
This influence must be regarded when calculating the timings for the C167SR.
Direct Drive
When pin P0.15 (P0H.7) is low (‘0’) during reset the on-chip phase locked loop is disabled and the
CPU clock is directly driven from the oscillator with the input clock signal.
The frequency of
duration of an individual TCL) is defined by the duty cycle of the input clock
The timings listed below that refer to TCLs therefore must be calculated using the minimum TCL
that is possible under the respective circumstances. This minimum value can be calculated via the
following formula:
For two consecutive TCLs the deviation caused by the duty cycle of
duration of 2TCL is always 1/
timings that require an odd number of TCLs (1,3,...). Timings that require an even number of TCLs
(2,4,...) may use the formula 2TCL = 1/
Note: The address float timings in Multiplexed bus mode (t
Semiconductor Group
Phase Locked Loop Operation
Direct Clock Drive
TCL (TCL
f
f
f
f
XTAL
CPU
XTAL
CPU
max
f
TCL
CPU
= 1/
directly follows the frequency of
min
f
XTAL
= 1/
f
f
XTAL
XTAL
DC
. The minimum value TCL
max
DC
) instead of TCL
min
f
XTAL
.
43
min
f
.
XTAL
(DC = duty cycle)
min
so the high and low time of
11
therefore has to be used only once for
and t
45
) use the maximum duration of
f
XTAL
is compensated so the
f
f
XTAL
CPU
TCL TCL
TCL TCL
. Both edges of the
.
f
CPU
C167SR
(i.e. the
f
CPU
.