LM3S3768 Luminary Micro, Inc, LM3S3768 Datasheet - Page 697

• Manufacturer Part Number: LM3S3768
• Description: Lm3s3768 Arm Microcontroller
• Manufacturer: Luminary Micro, Inc

24.2.2
June 02, 2008
Clocks
Table 24-8. Phase Locked Loop (PLL) Characteristics
a. The exact value is determined by the crystal value programmed into the XTAL field of the Run-Mode Clock Configuration
b. PLL frequency is automatically calculated by the hardware based on the XTAL field of the RCC register.
Table 24-9. Clock Characteristics
a. The ADC must be clocked from the PLL or directly from a 14-MHz to 18-MHz clock source to operate properly.
Table 24-10. Crystal Characteristics
Parameter
f
f
f
T
f
f
f
f
f
f
t
f
f
f
Parameter Name
Frequency
Frequency tolerance
Aging
Oscillation mode
Temperature stability (-40°C to 85°C)
Motional capacitance (typ)
Motional inductance (typ)
Equivalent series resistance (max)
Shunt capacitance (max)
Load capacitance (typ)
Drive level (typ)
ref_crystal
ref_ext
pll
IOSC
IOSC30KHZ
XOSC
XOSC_XTAL
XOSC_EXT
MOSC
MOSC_per
ref_crystal_bypass
ref_ext_bypass
system_clock
READY
Parameter
(RCC) register.
Parameter Name
Crystal reference
External clock reference
PLL frequency
PLL lock time
Parameter Name
Internal 12 MHz oscillator frequency
Internal 30 KHz oscillator frequency
Hibernation module oscillator frequency
Crystal reference for hibernation oscillator
External clock reference for hibernation module
Main oscillator frequency
Main oscillator period
Crystal reference using the main oscillator (PLL in BYPASS mode)
a
External clock reference (PLL in BYPASS mode)
System clock
b
a
a
Parallel
3.579545
3.579545
13.9
7.15
100
±50
±25
16
±5
80
10
16
Min
-
-
Preliminary
Parallel
18.5
±50
±25
100
100
Nom
9.5
12
±5
10
16
400
-
-
-
16.384
16.384
Parallel
Max
0.5
27.8
14.3
±50
±25
120
100
±5
10
16
-
8
Value
Unit
MHz
MHz
MHz
ms
a
Parallel
37.0
19.1
±50
±25
160
100
±5
10
16
6
Parallel
55.6
28.6
±50
±25
200
100
±5
10
16
4
Parallel
63.5
32.7
±50
±25
220
100
Min
3.5
±5
10
16
8.4
21
61
1
1
0
0
-
-
-
4.194304
4.194304
LM3S3768 Microcontroller
32.768
Units
ppm/yr
Nom
MHz
ppm
ppm
mH
µW
12
30
pF
pF
pF
Ω
-
-
-
-
-
-
16.384
16.384
1000
Max
15.6
39
50
50
-
-
-
MHz
MHz
MHz
MHz
MHz
MHz
MHz
Unit
KHz
KHz
ns
697