HD64F3437TF16 Datasheet, PDF (216/752 Pages) Hitachi Semiconductor – 12 V must not be applied to the S-mask model (single-power-supply specification), as this may permanently damage the device.

No. Description
Timing
3
High → low:
CKS1 and CKS0 are
Old clock
source
rewritten while old clock
source is high and new
clock source is low.
New clock
source
*
FRC clock
pulse
FRC
N
4
High → high:
CKS1 and CKS0 are
rewritten while both
Old clock
source
clock sources are high.
New clock
source
FRC clock
pulse
N+1
CKS rewrite
N+2
FRC
N
N+1
N+2
CKS rewrite
Note: * The switching of clock sources is regarded as a falling edge that increments FRC.
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