rs5c62 RICOH Co.,Ltd., rs5c62 Datasheet - Page 39

• Manufacturer Part Number: rs5c62
• Description: Real-time Clock
• Manufacturer: RICOH Co.,Ltd.

Category
Question 3 : How many variation factors should be considered? (Subject to use of fixed capacitors and
no adjustment of oscillation frequencies)
1. The possible factors behind oscillation frequency variations are :
2. On the other hand, the possible factors behind surrounding environment variations are :
Variations in 1 - 1 to 1 - 4 are listed in the order of decreasing degree. The individual variations
are described below :
1-1. Most crystals seem to have variations in their frequencies on the order of ±20ppm while
1-2. Sample measurements of variations in oscillation characteristics of the ICs are shown
1-3. Variations in oscillation frequencies differ slightly depending on the capacitance of external
1-4. Normally, variations in floating capacitance present on the actual PCB seem to be small
2-1. Variations in ambient temperature are dominantly affected by the temperature characteris-
2-2. Because the oscillatory circuit inside the ICs is driven by constant voltage, Variations in
1-1. Variations in frequencies of crystals,
1-2. Variations in oscillation characteristics of the ICs,
1-3. Variations in the external oscillatory capacitors C
1-4. Variations in floating capacitance present on the actual PCB.
2-1. Variations in ambient temperature, and
2-2. Variations in supply voltage.
some crystals may have smaller variations. For variations in frequencies of individual crys-
tals, inquire of their suppliers.
graphically on the next page. Note that these measurements are not guaranteed ones and
are therefore intended for reference use only.
oscillatory capacitors C
C
tion frequencies, they should have small variations relative to their capacitance (see the
graphs in 10.5 and 10.6 of “10. Typical Characteristics”).
enough to be negligible.
tics of fork-shaped crystal oscillators (forming an upward-facing quadratic curve) (see the
graph in 10.8 of “10. Typical Characteristics”).
oscillation frequencies due to variations in supply voltage measure±0.5ppm or less on real
terms at room temperature with the VDD pin input ranging from 2.5V to 5.5V (see the
graph in 10.7 of “10. Typical Characteristics”).
D
, the greater the variations in oscillation frequencies. Subject to no adjustment of oscilla-
G
and C
Questions and Answers
D
. More specifically, the smaller the capacitance of C
G
and C
D
, and
RP/RF/RS5C62
G
and
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