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RTC - 72421 / 72423
Page - 20 MQ - 162 - 03
Reference data
[Finding the frequency stability]
1. Frequency and temperature characteristics can be approximated
using the following equations.
∆
fT =
α
(
θ
T -
θ
X )
2
∆
fT
: Frequency deviation in any
temperature
α
( 1 / °C
2
)
: Coefficient of secondary temperature
(
−
0.035
±
0.005 )
×
10
-6
/ °C
2
θ
T (
°
C )
: Ultimate temperature (+25
±
5 °C)
θ
X (
°
C )
: Any temperature
2. To determine overall clock accuracy, add the frequency precision
and voltage characteristics.
∆
f/f
=
∆
f/fo +
∆
fT +
∆
fV
∆
f/f
: Clock accuracy (stable frequency) in
any temperature and voltage.
∆
f/fo
: Frequency precision
∆
fT
: Frequency deviation in any
temperature.
∆
fV
: Frequency deviation in any voltage.
3. How to find the date difference
Date Difference =
∆
f/f
×
86400(s)
* For example:
∆
f/f = 11.574
×
10
-6
is an error of
approximately 1 second/day.
1. Example of frequency and temperature characteristics
-150
-100
-50
0
-50 0 +50 +100
Temperature [
°
C]
Frequency
∆
f
T
×
10
-6
θ
T
= +25
°
C Typ.
α
= -0.035
×
10
-6
Typ.
2. Frequency voltage characteristics ( Typ. )
Frequency[x10
-
6
]
-4
-2
0
+2
+4
6 2 3 4 5
Supply Voltage(V
DD
) [V]
Condtions
5 V reference,Ta=+25
°
C
3. Current consumption voltage characteristics ( Typ. )
Current consumption[
µ
A]
1
2
3
4
5
62345
Supply voltage(V
DD
)
Conditions
CS1=0 V, No load, Ta=+25
°
C
Note: This data shows average values for a sample lot.
For rated values, see the specifications.