
Technical Data
MC68HC705C8A
—
Rev. 3
182
Electrical Specifications
MOTOROLA
Electrical Specifications
13.10 3.3-Volt Control Timing
Figure 13-5. Timer Relationships
Characteristic
(1)
Symbol
Min
Max
Unit
Frequency of operation
Crystal option
External clock option
f
OSC
—
dc
2.0
2.0
MHz
Internal operating frequency
Crystal (f
OSC
÷
2)
External clock (f
OSC
÷
2)
f
OP
—
dc
1.0
1.0
MHz
Cycle time (see
Figure 13-7
)
t
CYC
1000
—
ns
Crystal oscillator startup time (see
Figure 13-7
)
t
OXOV
—
100
ms
Stop recovery startup time (crystal oscillator)
(see
Figure 13-6
)
t
ILCH
—
100
ms
RESET pulse width, excluding power-up
(see
Figure 13-7
)
t
RL
8
—
t
CYC
Timer
Resolution
(2)
Input capture pulse width (see
Figure 13-5
)
Input capture pulse period (see
Figure 13-5
)
t
RESL
t
TH
, t
TL
t
TLTL
4.0
250
(3)
—
—
—
t
CYC
ns
t
CYC
Interrupt pulse width low (edge-triggered)
(see
Figure 4-2. External Interrupt Timing
)
t
ILIH
250
—
ns
Interrupt pulse period
(see
Figure 4-2. External Interrupt Timing
)
t
ILIL
(4)
—
t
CYC
OSC1 pulse width
t
OH
, t
OL
200
—
ns
1. V
DD
= 3.3 Vdc
±
0.3 Vdc, V
SS
= 0 Vdc; T
A
= T
L
to T
H
2. Since a 2-bit prescaler in the timer must count four internal cycles (t
CYC
), this is the limiting minimum factor in determining
the timer resolution.
3. The minimum period, t
TLTL
, should not be less than the number of cycle times it takes to execute the capture interrupt ser-
vice routine plus 24 t
CYC
.
4. The minimum period, t
ILIL
, should not be less than the number of cycle times it takes to execute the interrupt service routine
plus 19 t
CYC
.
t
TLTL
*
EXTERNAL SIGNAL
(TCAP PIN 37)
t
TH
*
t
TL
*
*
Refer to timer resolution data in
Figure 13-6
and
Figure 13-7
.