Datasheet

ST10F269
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V
DD
= 5V ± 10%, V
SS
= 0V, T
A
= -40 to +125 °C (TQFP144 devices)
1. Theoretical minimum. The real minimum value depends on the duty cycle of the input clock signal. 32MHz is the maximum input frequency
when using an external crystal oscillator. However, 32MHz can be applied with an external clock source.
2. The input clock signal must reach the defined levels V
IL
and V
IH2
.
Figure 70 : External Clock Drive XTAL1
21.4.9 - Memory Cycle Variables
The tables below use three variables which are derived from the BUSCONx registers and represent the
special characteristics of the programmed memory cycle. The following table describes, how these
variables are to be computed.
Parameter Symbol
f
CPU
= f
XTAL
f
CPU
= f
XTAL
/ 2
f
CPU
= f
XTAL
x F
F = 1.5/2,/2.5/3/4/5
Unit
Minimum Maximum Minimum Maximum Minimum Maximum
Oscillator period t
OSC
SR
31.25
1
– 15.625 – 31.25 x N –
ns
High time t
1
SR
12.5
2
–6.25
2
– 12.5
2
–
ns
Low time t
2
SR
12.5
2
–6.25
2
– 12.5
2
–
ns
Rise time t
3
SR
– 3.125
2
–1.56
2
–3.125
2
ns
Fall time t
4
SR
– 3.125
2
–1.56
2
–3.125
2
ns
Description Symbol Values
ALE Extension t
A
TCL x [ALECTL]
Memory Cycle Time wait states t
C
2TCL x (15 - [MCTC])
Memory Tri-state Time t
F
2TCL x (1 - [MTTC])
t
1
t
3
t
4
V
IL
t
2
t
OSC
V
IH2