MC68HC908EY16 Datasheet, PDF (246/278 Pages) Motorola, Inc – Microcontrollers

Electrical Specifications
20.9 Trimmed Accuracy of the Internal Clock Generator
The unadjusted frequency of the low-frequency base clock (IBASE), when the comparators in the
frequency comparator indicate zero error, can vary as much as ±25% due to process, temperature, and
voltage. The trimming capability exists to compensate for process affects. The remaining variation in
frequency is due to temperature, voltage, and change in target frequency (multiply register setting). These
affects are designed to be minimal, however variation does occur. Better performance is seen with lower
settings of N.
20.9.1 Trimmed Internal Clock Generator Characteristics
Characteristic⁽¹⁾
Symbol
Min
Typ
Max
Unit
Absolute trimmed internal oscillator tolerance^(2),(3)
–40°C to 85°C
–40°C to 135°C
F_{abs_tol}
—
±2.0
±3.5
%
—
±2.5
±5.0
Variation over temperature^{(3), (4)}
V_{ar_temp}
—
0.05
0.08
%/°C
Variation over voltage^{(3), (5)}
25°C
–40°C to 85°C
–40°C to 135°C
V_{ar_volt}
—
—
—
1.0
1.0
2.0
2.0
%/V
1.0
2.0
1. These specifications concern long-term frequency variation. Each measurement is taken over a 1-ms period.
2. Absolute value of variation in ICG output frequency, trimmed at nominal V_DD and temperature, as temperature and V_DD
are allowed to vary for a single given setting of N.
3. Specification is characterized but not tested.
4. Variation in ICG output frequency for a fixed N and voltage
5. Variation in ICG output frequency for a fixed N
MC68HC908EY16 • MC68HC908EY8 Data Sheet, Rev. 10
246
Freescale Semiconductor