LM3S1958 Datasheet, PDF (406/435 Pages) List of Unclassifed Manufacturers – Microcontroller

Electrical Characteristics
19.2
19.2.1
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 19-1. Load Conditions
pin
C_L = 50 pF
GND
19.2.2
Clocks
Table 19-5. 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 - 8.192 MHz
External clock reference^a 3.579545 - 8.192 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 19-6. Clock Characteristics
Parameter Parameter Name
Min Nom Max Unit
f_IOSC
f_IOSC30KHZ
f_XOSC
Internal 12 MHz oscillator frequency
Internal 30 KHz oscillator frequency
Hibernation module oscillator frequency
8.4 12 15.6 MHz
21 30
39 KHz
- 4.194304 - MHz
f_{XOSC_XTAL}
Crystal reference for hibernation oscillator
- 4.194304 - MHz
f_{XOSC_EXT}
f_MOSC
t_{MOSC_per}
External clock reference for hibernation module
Main oscillator frequency
Main oscillator period
- 32.768 - KHz
1
-
8 MHz
125 - 1000 ns
f_{ref_crystal_bypass}
Crystal reference using the main oscillator (PLL in BYPASS mode)
a
1
-
8 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 19-7. Crystal Characteristics
Parameter Name
Frequency
Value
8
6
4
Units
3.5 MHz
406
June 14, 2007
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