
RTC - 72421 / 72423
Page - 20
MQ162-04
! Reference data
[Finding the frequency stability]
1. Frequency and temperature characteristics can be approximated
using the following equations.
fT = α ( θT - θX )2
fT
: Frequency deviation in any
temperature
α
( 1 / °C
2 )
: Coefficient of secondary temperature
(
0.035±0.005 ) × 10-6 / °C2
θT
(
°C )
: Ultimate temperature (+25
±5 °C)
θX( °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]
F
re
que
nc
y
fT
× 10-6
θT = +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(VDD) [V]
Condtions
5 V reference,Ta=+25
°C
3. Current consumption voltage characteristics ( Typ. )
Current consumption[
A]
1
2
3
4
5
6
2345
Supply voltage(VDD)
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.