LM3S3748 Datasheet, PDF (695/753 Pages) List of Unclassifed Manufacturers – Microcontroller

LM3S3748 Microcontroller
24.2.2
Clocks
Table 24-8. Phase Locked Loop (PLL) Characteristics
Parameter Parameter Name
Min Nom Max Unit
f_{ref_crystal}
f_{ref_ext}
f_pll
Crystal reference^a
3.579545 - 16.384 MHz
External clock reference^a 3.579545 - 16.384 MHz
PLL frequency^b
-
400 - MHz
T_READY PLL lock time
-
- 0.5 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.
Table 24-9. Clock Characteristics
Parameter Parameter Name
Min Nom Max Unit
f_IOSC
Internal 12 MHz oscillator frequency
f_IOSC30KHZ
Internal 30 KHz oscillator frequency
f_XOSC
Hibernation module oscillator frequency
f_{XOSC_XTAL}
Crystal reference for hibernation oscillator
f_{XOSC_EXT}
External clock reference for hibernation module
f_MOSC
Main oscillator frequency
t_{MOSC_per}
Main oscillator period
f_{ref_crystal_bypass}
Crystal reference using the main oscillator (PLL in BYPASS mode)
a
8.4 12
15.6 MHz
21 30
39 KHz
- 4.194304 - MHz
- 4.194304 - MHz
- 32.768 - KHz
1
- 16.384 MHz
61
-
1000 ns
1
- 16.384 MHz
f_{ref_ext_bypass} External clock reference (PLL in BYPASS mode)^a
0
-
50 MHz
f_{system_clock}
System clock
0
-
50 MHz
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 Name
Value
Units
Frequency
16
12
8
6
4
3.5 MHz
Frequency tolerance
±50 ±50 ±50 ±50 ±50 ±50 ppm
Aging
±5
±5
±5
±5
±5
±5 ppm/yr
Oscillation mode
Parallel Parallel Parallel Parallel Parallel Parallel -
Temperature stability (-40°C to 85°C) ±25 ±25 ±25 ±25 ±25 ±25 ppm
Motional capacitance (typ)
13.9 18.5 27.8 37.0 55.6 63.5 pF
Motional inductance (typ)
7.15 9.5 14.3 19.1 28.6 32.7 mH
Equivalent series resistance (max)
80 100 120 160 200 220 Ω
Shunt capacitance (max)
10
10
10
10
10
10 pF
Load capacitance (typ)
16
16
16
16
16
16 pF
Drive level (typ)
100 100 100 100 100 100 µW
April 08, 2008
695
Preliminary