LM3S5D91-IQC80-A1 Datasheet, PDF (1260/1342 Pages) Texas Instruments – Stellaris LM3S5D91 Microcontroller

Electrical Characteristics
NRND: Not recommended for new designs.
25.8.4
Main Oscillator Specifications
Table 25-11. Main Oscillator Clock Characteristics
Parameter
Parameter Name
Min
Nom
Max
Unit
F_MOSC
Main oscillator frequency
1
-
T_{MOSC_PER}
T_{MOSC_SETTLE}
Main oscillator period
Main oscillator settling time^a
61
-
17.5
-
F_{REF_XTAL_BYPASS}
Crystal reference using the main oscillator
(PLL in BYPASS mode)^b
1
-
16.384
1000
20
16.384
MHz
ns
ms
MHz
F_{REF_EXT_BYPASS}
External clock reference (PLL in BYPASS
mode)^b
0
-
50
MHz
DC_{MOSC_EXT}
External clock reference duty cycle
45
-
55
%
a. This parameter is highly sensitive to PCB layout and trace lengths, which may make this parameter time longer. Care
must be taken in PCB design to minimize trace lengths and RLC (resistance, inductance, capacitance).
b. If the ADC is used, the crystal reference must be 16 MHz ± .03% when the PLL is bypassed.
Table 25-12. Supported MOSC Crystal Frequencies^a
Crystal Frequency (MHz) Not Using the PLL
Crystal Frequency (MHz) Using the PLL
1.000 MHz
reserved
1.8432 MHz
reserved
2.000 MHz
reserved
2.4576 MHz
reserved
3.579545 MHz
3.6864 MHz
4 MHz (USB)
4.096 MHz
4.9152 MHz
5 MHz (USB)
5.12 MHz
6 MHz (reset value)(USB)
6.144 MHz
7.3728 MHz
8 MHz (USB)
8.192 MHz
10.0 MHz (USB)
12.0 MHz (USB)
12.288 MHz
13.56 MHz
14.31818 MHz
16.0 MHz (USB)
16.384 MHz
a. Frequencies that may be used with the USB interface are indicated in the table.
1260
Texas Instruments-Production Data
October 05, 2012