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C165UTAH
Architectural Overview
Data Sheet
39
2001-02-23
Table 10
C165UTAH Clock Generation Modes
PLL Operation
On power-up the PLL provides a stable clock signal within ca. 1 ms after VDD has
reached 3.3 V
±
10%, even if there is no external clock signal (in this case the PLL will run
on its basic frequency of 2...5 MHz). The PLL starts synchronizing with the external clock
signal as soon as it is available. Within ca. 1 ms after stable oscillations of the external
clock within the specified frequency range the PLL will be synchronous with this clock at
a frequency of
F
* f
OSC
, ie. the PLL locks to the external clock.
Note:
If the C165UTAH is required to operate on the desired CPU clock directly after
reset make sure that RSTIN remains active until the PLL has locked (ca. 1 ms).
When PLL operation is selected the CPU clock is a selectable multiple of the oscillator
frequency, ie. the input frequency. The table above lists the possible selections.
P0H.7-P0H.5 Frequency
Divider Activation
USB Interface is NOT used
0
0
1
f
XTAL
* 0.5
direct drive, D1 not active, D2 active, PLL free running (2..5 MHZ)
Note:
The PLL can be switched off completely by setting bit
PLLDIS = ’1’ (SYSCON3.13, see page 470).
0
1
0
f
XTAL
* 1.5
f
XTAL
* 1.0
D1 not active, D2 not active, F = 1.5
0
1
1
direct drive, D1 not active, D2 not active, PLL free running (2..5
MHz)
Note:
The PLL can be switched off completely by setting bit
PLLDIS = ’1’ (SYSCON3.13, see page 470).
1
0
0
f
XTAL
* 6.0
f
XTAL
* 1.125
D1 active, D2 active, F = 1.125
f
XTAL
* 3.0
D1 not active, D2 not active, F = 3.0
f
XTAL
* 4.5
D1 not active, D2 not active, F
=
4.5, Default Mode
f
XTAL
* 0.375
D1 active, D2 active, F = 0.375
D1 not active, D2 not active, F = 6.0
1
0
1
1
1
0
1
1
1
0
0
0
USB Interface is used (USB clock must be 48 MHz)
1
1
0
f
XTAL
* 3
D1 not active, D2 not active, F = 3.0
f
USB
=
def
48 MHz
D1 not active, D2 not active, F = 4.5, Default Mode
f
USB
=
def
48 MHz
Τ
f
XTAL
= 8 MHz
Τ
f
XTAL
= 8 MHz
Τ
f
CPU
= 24 MHz
1
1
1
f
XTAL
* 4.5
Τ
f
CPU
= 36 MHz