SM470R1B1M-HT Datasheet, PDF (41/67 Pages) Texas Instruments – 16/32-BIT RISC FLASH MICROCONTROLLER

SM470R1B1M-HT
www.ti.com
SPNS155F – SEPTEMBER 2009 – REVISED AUGUST 2012
External Reference Resonator/Crystal Oscillator Clock Option
The oscillator is enabled by connecting the appropriate fundamental 4–10 MHz resonator/crystal and load
capacitors across the external OSCIN and OSCOUT pins as shown in Figure 8 (a). The oscillator is a single-
stage inverter held in bias by an integrated bias resistor. This resistor is disabled during leakage test
measurement and HALT mode. 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 start-up and operation over
temperature/voltage extremes. Please note that external crystal mode is guaranteed to function only within
the temperature ranges of -40°C to 150°C. Above this recommended temperature range it is strongly
recommended to use an external clock signal as shown in Figure 8 (b).
An external oscillator source can be used by connecting a 1.8-V clock signal to the OSCIN pin and leaving the
OSCOUT pin unconnected (open) as shown in Figure 8b.
OSCIN
OSCOUT
OSCIN
OSCOUT
C1^(A)
Crystal
"
(a)
C2^(A)
!External
Clock Signal
(toggling 0 - V_CC)
(b)
A. The values of C1 and C2 should be provided by the resonator/crystal vendor.
Figure 8. Crystal/Clock Connection
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