dsp56858 Freescale Semiconductor, Inc, dsp56858 Datasheet - Page 29

• Manufacturer Part Number: dsp56858
• Description: 16-bit Digital Signal Controllers
• Manufacturer: Freescale Semiconductor, Inc

4.5.2
The recommended method of connecting an external clock is given in
source is connected to XTAL and the EXTAL pin is held at ground, V
bit in CGM must be set to 0.
4.5.3
The recommended method of connecting an external clock is given in
source is connected to XTAL and the EXTAL pin is held at V
set to 0.
Freescale Semiconductor
Operating Conditions: V
Frequency of operation (external clock driver)
Clock Pulse Width
External clock input rise time
External clock input fall time
1. See
2. External clock input rise time is measured from 10% to 90%.
3. External clock input fall time is measured from 90% to 10%.
4. Parameters listed are guaranteed by design.
Figure 4-7 Connecting a High Speed External Clock Signal using XTAL
Figure 4-8 Connecting a Low Speed External Clock Signal using XTAL
High Speed External Clock Source (> 4MHz)
Low Speed External Clock Source (2-4MHz)
Figure 4-7
Table 4-5 External Clock Operation Timing Requirements
Characteristic
4
SS
for details on using the recommended connection of an external clock driver.
= V
SSIO
3, 4
= V
2, 4
SSA
= 0 V, V
(up to 240MHz)
DD
56858 Technical Data, Rev. 6
= 1.62-1.98V, V
External
1
(2-4MHz)
Clock
External
XTAL
XTAL
Clock
56858
Symbol
56858
f
t
t
t
osc
PW
rise
DDIO
fall
EXTAL
EXTAL
GND,
V
or V
= V
DDA
DDA
DDA
V
/2
= 3.0–3.6V, T
DDA
DDA
Min
6.25
—
—
0
/2
,
/2. The TOD_SEL bit in CGM must be
A
= –40° to +120°C, C
DDA
Typ
Figure
Figure
—
—
—
—
, or V
4-7. The external clock
4-8. The external clock
DDA
Max
TBD
TBD
240
L
—
≤ 50pF, f
4
/2. The TOD_SEL
External Clock Operation
op
= 120MHz
Unit
MHz
ns
ns
ns
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