Datasheet

External Clock Operation
56F807 Technical Data Technical Data, Rev. 16
Freescale Semiconductor 31
3.4.3 External Clock Source
The recommended method of connecting an external clock is given in Figure 3-9. The external clock
source is connected to XTAL and the EXTAL pin is grounded.
Figure 3-9 Connecting an External Clock Signal
Figure 3-10 External Clock Timing
Table 3-8 External Clock Operation Timing Requirements
5
Operating Conditions: V
SS
= V
SSA
= 0 V, V
DD
= V
DDA
= 3.0–3.6 V, T
A
= –40° to +85°C
Characteristic Symbol Min Typ Max Unit
Frequency of operation (external clock driver)
1
1. See Figure 3-9 for details on using the recommended connection of an external clock driver.
f
osc
0—80MHz
Clock Pulse Width
2
,
3
2. The high or low pulse width must be no smaller than 6.25ns or the chip will not function. However, the high pulse width
does not have to be any particular percent of the low pulse width.
3. Parameters listed are guaranteed by design.
t
PW
6.25 — — ns
56F807
XTAL
EXTAL
External
V
SS
Clock
External
Clock
V
IH
V
IL
Note: The midpoint is V
IL
+ (V
IH
– V
IL
)/2.
90%
50%
10%
90%
50%
10%
t
PW
t
PW