LM3S2139 Luminary Micro, Inc, LM3S2139 Datasheet - Page 471

• Manufacturer Part Number: LM3S2139
• Description: Lm3s2139 Arm Microcontroller
• Manufacturer: Luminary Micro, Inc

20.2
20.2.1
20.2.2
July 25, 2008
AC Characteristics
Load Conditions
Unless otherwise specified, the following conditions are true for all timing measurements. Timing
measurements are for 4-mA drive strength.
Figure 20-1. Load Conditions
Clocks
Table 20-6. 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 20-7. 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 20-8. Crystal Characteristics
Parameter
f
f
f
T
f
f
f
t
f
f
f
Parameter Name
Frequency
Frequency tolerance
Aging
Oscillation mode
ref_crystal
ref_ext
pll
IOSC
IOSC30KHZ
MOSC
MOSC_per
ref_crystal_bypass
ref_ext_bypass
system_clock
READY
Parameter
pin
(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
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
GND
C
L
b
= 50 pF
a
a
3.579545
3.579545
Parallel
Min
±50
±5
8
-
-
Preliminary
Parallel
Nom
400
±50
±5
-
-
-
6
Value
8.192
8.192
Max
0.5
Parallel
-
±50
±5
4
MHz
MHz
MHz
Unit
ms
a
Parallel
±50
3.5
±5
Units
ppm/yr
MHz
ppm
-
Min
125
8.4
21
1
1
0
0
Nom
LM3S2139 Microcontroller
12
30
-
-
-
-
-
1000
Max
15.6
39
25
25
8
8
MHz
MHz
MHz
MHz
MHz
Unit
KHz
ns
471