MC9S12P128 Datasheet, PDF (229/564 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

S12 Clock, Reset and Power Management Unit (S12CPMU) Block Description
TCTRIM[3:0]
Indicative TC variation
0000
0 (nominal TC of the IRC1M)
0001
-0.54%
0010
-1.08%
0011
-1.63%
0100
-2.20%
0101
-2.77%
0110
-3.33%
0111
-3.91%
1000
0 (nominal TC of the IRC1M)
1001
+0.54%
1010
+1.07%
1011
+1.59%
1100
+2.11%
1101
+2.62%
1110
+3.12%
1111
+3.62%
Figure 7-28. TC trimming of the frequency of the IRC1M
NOTE
Since the IRC1M frequency is not a linear function of the temperature, but
more like a parabola, the above relative variation is only an indication and
should be considered with care.
Be aware that the output frequency varies with the TC trimming, of
respectively +/- 0.8%, +/-1.6%, +/-2.4%, +/-3.2%, +/-4.0%, +/-4.8%, +/-
5.5% ambient temperature, from the lowest to the greatest TC correction.
A frequency trimming correction is therefore necessary if a TC
trimming correction has been performed. For high TC trimming
corrections (+/-4 or 5%), and for very worst case silicon, the margin left to
trim the part at 1MHz may be small, but should be sufficient.
7.3.2.21 S12CPMU Oscillator Register (CPMUOSC)
This registers configures the external oscillator (OSCLCP).
S12P-Family Reference Manual, Rev. 1.12
Freescale Semiconductor
229