Datasheet

Trimmed Accuracy of the Internal Clock Generator
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 Data Sheet, Rev. 2.1
Freescale Semiconductor 189
Figure 17-1 through Figure 17-4 illustrate typical performance. The formula for this variation of frequency
is (measured-nominal)/nominal. Figure 17-1 shows the variation in ICG frequency for a part trimmed at
nominal voltage and temperature across V
DD
and temperature for a 3-V application with multiply register
(N) set to 1. Figure 17-2 shows 5 V.
Figure 17-1. Example of Frequency Variation Across Temperature,
Trimmed at Nominal 3 Volts, 25°C, and N = 1
Figure 17-2. Example of Frequency Variation Across Temperature,
Trimmed at Nominal 3 Volts, 25°C, and N = 104
-6.00%
-4.00%
-2.00%
0.00%
2.00%
4.00%
6.00%
2.7
3
3.3
2.7
0.00862069 -0.004310345 -0.021551724 -0.036637931
3
0.012931034 0 -0.023706897 -0.034482759
3.3
0.00862069 0 -0.019396552 -0.034482759
-40 25 85 125
-6.00%
-4.00%
-2.00%
0.00%
2.00%
4.00%
6.00%
2.7
3
3.3
2.7
0.021688017 -0.004114642 -0.035937247 -0.054665964
3
0.027728231 0 -0.033768445 -0.055436193
3.3
0.033525215 0.006019945 -0.032552294 -0.055456462
-40 25 85 125