Set
Reset
Q
HFXTIE
POR
HFXT_OscFault /
SET_HFXTIFG
Set
Reset
Q
LFXTIE
LFXT_OscFault /
SET_LFXTIFG
Set
Reset
Q
DCOR_OPNIE
DCOR_Open_OscFault /
SET_DCOR_OPNIFG
To shared
NMI/interrupt
CLR_LFXTIFG
CLR_HFXTIFG
CLR_DCOR_OPNIFG
DCOR_OPNIFG
LFXTIFG
HFXTIFG
Set
Reset
Q
DCOR_Short_OscFault
CLR bit in RSTCTL_CSRESET_CLR
POR
DCOR_SHTIFG
Clock System Operation
390
SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
Clock System (CS)
If LFXT is sourcing any system clock (ACLK, BCLK, MCLK, HSMCLK, SMCLK, or LFXTCLK) and a fault
is detected, the system clock is automatically switched to REFO for its clock source.
The REFO clock in
fail-safe mode of operation always runs at 32.768-kHz and the REFOFSEL bit setting does not take
any effect.
The LFXT fault logic works in all power modes, including LPM3 mode. Similarly, If HFXT is
sourcing MCLK, HSMCLK, or SMCLK, and a fault is detected, the system clocks are automatically
switched to SYSOSC for their clock source. The HFXT fault logic does not work in low-power modes as
the high-frequency operation in low-power modes is not supported.
The fail-safe logic does not change the SELA, SELB, SELM, and SELS bit settings. The fail-safe
mechanism behaves the same in normal and bypass modes.
Figure 6-3. Oscillator Fault Logic