1. Software programs refclk limit registers
2. Missing Clock logic enabled by default
and re-enabled if missing clock status is
cleared
1. Power up
missing clock
detection
condition
2. Missing clock
logic enabled at
XRSn reset
1. H/W Clears 3 bit 10 MHz CLK Counter
2. H/W Clears 8 bit OSCCLK ref. clock
counter
3. Both counters start counting again
Missing
clock circuit
enabled
Yes
10MHz CLK
counter
overflow?
Yes
No
Logic reads
OSCCLK re.
clock counter
value
Ref clock high limit >=
OSCCLK ref.clock
counter >= Ref clock
low limit
No
1. system PLL bypassed
2. Clock to device = 10MHz Internal
Oscillator.CLK
3. Disable missing clock counters
4. C28 side PWMs tripped based on
configuration
In
p
u
t
C
lo
c
k
P
ro
p
e
r
Yes
CLOCKFAIL
condition
generated
Disable
missing clock
circuit
No
1. Generate NMI to M3 and C28 CPU
2. Start both NMIWD counters
Safety Features
122
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
System Control and Interrupts
Note:
The missing clock circuit is not active during the PLL 1024 cycle lock time. To avoid missing clock
detection, the user should extend the external reset (XRS) so it covers appropriate lock time.
shows the missing clock logic functional flow.
Figure 1-10. Missing Clock Detection Logic