MC68HC908GT16_07 Datasheet, PDF (262/292 Pages) Freescale Semiconductor, Inc – Microcontrollers

Electrical Specifications
20.12 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 effects. The remaining variation in
frequency is due to temperature, voltage, and change in target frequency (multiply register setting). These
effects are designed to be minimal, however variation does occur. Better performance is seen at 3 V and
lower settings of N.
20.12.1 2.7-Volt to 3.3-Volt Trimmed Internal Clock Generator Characteristics
Characteristic⁽¹⁾
Absolute trimmed internal oscillator tolerance^{(2), (3)}
–40°C to 85°C
Variation over temperature^{(3), (4)}
Variation over voltage^{(3), (5)}
25°C
–40°C to 85°C
Symbol
Min
F_{abs_tol}
—
V_{ar_temp}
—
V_{ar_volt}
—
—
Typ
2.5
0.03
0.5
0.7
Max
Unit
4.0
%
0.05
%/°C
2.0
%/V
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
20.12.2 4.5-Volt to 5.5-Volt Trimmed Internal Clock Generator Characteristics
Characteristic⁽¹⁾
Absolute trimmed internal oscillator tolerance^{(2), (3)}
–40°C to 85°C
Variation over temperature^{(3), (4)}
Variation over voltage^{(3), (5)}
25°C
–40°C to 85°C
Symbol
Min
F_{abs_tol}
—
V_{ar_temp}
—
V_{ar_volt}
—
—
Typ
4.0
0.05
1.0
1.0
Max
Unit
4.0
%
0.08
%/°C
2.0
%/V
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
MC68HC908GT16 • MC68HC908GT8 • MC68HC08GT16 Data Sheet, Rev. 5.0
262
Freescale Semiconductor