TMS570LS3135_17 Datasheet, PDF (58/172 Pages) Texas Instruments – 16- and 32-Bit RISC Flash Microcontroller

TMS570LS3135, TMS570LS2135, TMS570LS2125
SPNS164C – APRIL 2012 – REVISED APRIL 2015
www.ti.com
6.6 Clocks
6.6.1 Clock Sources
Table 6-8 lists the available clock sources on the device. Each of the clock sources 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 #
0
1
2
3
4
5
6
7
Table 6-8. Available Clock Sources
NAME
OSCIN
PLL1
Reserved
EXTCLKIN1
CLK80K
CLK10M
PLL2
EXTCLKIN2
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
Output From PLL2
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.
TI strongly encourages each customer to submit samples of the device to the resonator/crystal
vendors for validation. The vendors are equipped to determine what load capacitors will best tune
their resonator/crystal to the microcontroller device for optimum startup and operation over
temperature/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
58
System Information and Electrical Specifications
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