LM3S9B81 Datasheet, PDF (1085/1155 Pages) Texas Instruments – Stellaris® LM3S9B81 Microcontroller

Stellaris® LM3S9B81 Microcontroller
Figure 25-1. Load Conditions
pin
C_L
=
16
50
pF
pF
for
for
EPI0S[31:0] signals
other digital I/O signals
GND
25.2.2
Clocks
The following sections provide specifications on the various clock sources and mode.
25.2.2.1 PLL Specifications
The following tables provide specifications for using the PLL.
Table 25-9. Phase Locked Loop (PLL) Characteristics
Parameter Parameter Name
Min
Nom
Max
Unit
f_{REF_XTAL}
Crystal reference^a
3.579545
-
16.384
MHz
f_{REF_EXT}
f_PLL
T_READY
External clock reference^a
PLL frequency^b
PLL lock time
3.579545
-
16.384
-
400
-
0.562^c
-
1.38^d
MHz
MHz
ms
a. The exact value is determined by the crystal value programmed into the XTAL field of the Run-Mode Clock Configuration
(RCC) register.
b. PLL frequency is automatically calculated by the hardware based on the XTAL field of the RCC register.
c. Using a 16.384-MHz crystal
d. Using 3.5795-MHz crystal
Table 25-10 on page 1085 shows the actual frequency of the PLL based on the crystal frequency used
(defined by the XTAL field in the RCC register).
Table 25-10. Actual PLL Frequency
XTAL
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
0x0B
0x0C
0x0D
0x0E
0x0F
0x10
0x11
Crystal Frequency (MHz)
3.5795
3.6864
4.0
4.096
4.9152
5.0
5.12
6.0
6.144
7.3728
8.0
8.192
10.0
12.0
PLL Frequency (MHz)
400.904
398.1312
400
401.408
398.1312
400
399.36
400
399.36
398.1312
400
398.6773333
400
400
Error
0.0023%
0.0047%
-
0.0035%
0.0047%
-
0.0016%
-
0.0016%
0.0047%
0.0047%
0.0033%
-
-
June 29, 2010
Texas Instruments-Advance Information
1085