RTC-4573 Просмотр технического описания (PDF) - Seiko Epson Corp

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RTC-4573

Serial RTC with Alarm and Timer

Seiko Epson Corp 

n Reference data

( 1 ) Frequency temperature characteristics

( typical )

qT = 25°C TYP.

a = -0.035ppm/°C² TYP.

10

0

-10

-20

-30

-40

-50

-60

-70

-80

-90

-100

-110

-120

-40 -30 -20 -10

0

10 20 30 40 50 60 70 80

Temperature [°C]

Finding the frequency stability (clock error)

1. The frequency temperature characteristics can be

approximated by using the following expression:

DfT(ppm)=a (qT-qX) 2

D fT(ppm) : Frequency deviation at target temperature

a (ppm/°C2 ) : Secondary temperature coefficient

(-0.035 0.005ppm/°C2 )

q T(°C)

: Peak temperature (25°C ± 5°C)

q X(°C)

: Target temperature

2. To determine the overall clock accuracy, add the

frequency tolerance and the voltage characteristics:

Df/f(ppm) = Df/f0 + DfT + DfV

D f/f (ppm) : Clock accuracy at a given temperature

and voltage

D f/f 0 (ppm) : Frequency tolerance

D fT (ppm) : Temperature dependent frequency

deviation

D fV (ppm) : Voltage dependent frequency deviation

3. Finding the daily deviation:

Daily deviation (seconds) = Df/f x 10-6 x 86400

The clock error is one second per day at 11.574 ppm.

( 2 ) Frequency voltage characteristics

( typical )

Frequency[ppm]

+ 10

Conditions

3V reference , Ta=+25°C

+5

0

Supply voltage VDD[V]

-5

- 10

2

3

4

5

( 3 ) Current consumption voltage characteristics

( typical )

Current consumption [µA]

4

Conditions

CE0,CE1=0V,No load

3

Ta=+25 °C

2

1

Supply voltage VDD[V]

2

3

4

5

Note : This data shows average values for a sample lot.

For rated values, see the spacifications on page 3.

Page-10

Aug.1998

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