TMS570LS0914_16 Datasheet, PDF (51/163 Pages) Texas Instruments – 16- and 32-Bit RISC Flash Microcontroller

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TMS570LS0914
SPNS225D – JUNE 2013 – REVISED NOVEMBER 2016
6.6 Clocks
6.6.1 Clock Sources
Table 6-8 lists the available clock sources on the device. Each clock source can be enabled or disabled
using the CSDISx registers in the system module. The clock source number in the table corresponds to
the control bit in the CSDISx register for that clock source.
Table 6-8 also shows the default state of each clock source.
CLOCK
SOURCE NO.
0
1
2
3
4
5
6
7
NAME
OSCIN
PLL1
Reserved
EXTCLKIN1
LFLPO
HFLPO
Reserved
EXTCLKIN2
Table 6-8. Available Clock Sources
DESCRIPTION
Main oscillator
Output from PLL1
Reserved
External clock input 1
Low-frequency output of internal reference oscillator
High-frequency output of internal reference
oscillator
Reserved
External clock input 2
DEFAULT STATE
Enabled
Disabled
Disabled
Disabled
Enabled
Enabled
Disabled
Disabled
6.6.1.1 Main Oscillator
The oscillator is enabled by connecting the appropriate fundamental resonator/crystal and load capacitors
across the external OSCIN and OSCOUT pins as shown in Figure 6-4. The oscillator is a single-stage
inverter held in bias by an integrated bias resistor. This resistor is disabled during leakage test
measurement and low power modes.
NOTE
TI strongly encourages each customer to submit samples of the device to the
resonator/crystal vendors for validation. The vendors are equipped to determine which load
capacitors will best tune their resonator/crystal to the microcontroller device for optimum
start-up and operation over temperature and voltage extremes.
An external oscillator source can be used by connecting a 3.3-V clock signal to the OSCIN pin and leaving
the OSCOUT pin unconnected (open) as shown in Figure 6-4.
OSCIN
(see Note B)
Kelvin_GND
OSCOUT
C1
C2
(see Note A)
OSCIN
OSCOUT
External
Clock Signal
(toggling 0 V to 3.3 V)
Crystal
(a)
(b)
Note A: The values of C1 and C2 should be provided by the resonator/crystal vendor.
Note B: Kelvin_GND should not be connected to any other GND.
Figure 6-4. Recommended Crystal/Clock Connection
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System Information and Electrical Specifications
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