Epson RTC-72421 A, RTC-72421 B, RTC-72423, RTC-72423 A θ T, ∆ fT, ∆ fT, ∆ fV, Conditions, Frequency[x10-6], Supply voltage(VDD), Supply Voltage(VDD) [V], Current consumption[∝ A]

RTC - 72421 / 72423

„Reference data

1.Example of frequency and temperature characteristics

	θ T = +25	° C Typ.
⋅ 10-6	α = -0.035	⋅ 10-6Typ.
0

∆ fT	-50
Frequency
	-100
	-150
	-50	0	+50	+100

Temperature [° C]

[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 / °C2 )	: Coefficient of secondary temperature
		( − 0.035± 0.005 ) ⋅ 10-6 / °C2
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 ⋅ 10-6is an error of

approximately 1 second/day.

2. Frequency voltage characteristics ( Typ. )

Frequency[x10-6]

			Condtions
		5 V reference,Ta=+25 ° C
+4
+2
2	3	4	5	6
0
-2		Supply Voltage(VDD) [V]
-4

Note:	This data shows average values for a sample lot.
	For rated values, see the specifications.

3. Current consumption voltage characteristics ( Typ. )

Current consumption[∝ A]Conditions

CS1=0 V, No load, Ta=+25 ° C

5

4

3

2

1

2	3	4	5	6
	Supply voltage(VDD)

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