參數(shù)資料
型號: RV5C386A-E2
廠商: RICOH COMPANY LTD
元件分類: XO, clock
英文描述: I2C-bus Real-Time Clock ICs with Voltage Monitoring Function
中文描述: 0 TIMER(S), REAL TIME CLOCK, PDSO10
封裝: 4 X 2.90 MM, 1.20 MM HEIGHT, SSOP-10
文件頁數(shù): 29/42頁
文件大?。?/td> 362K
代理商: RV5C386A-E2
PRELIMINARY RV5C386A
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- 29 -
14.2.4.
Oscillation Adjustment Circuit
The oscillation adjustment circuit can be used to correct a time count gain or loss with high precision by
varying the number of 1-second clock pulses once per 20 seconds. When such oscillation adjustment is not
to be made, the oscillation adjustment circuit can be disabled by writing the settings of "*, 0, 0, 0, 0, 0, *" ("*"
representing "0" or "1") to the F6, F5, F4, F3, F2, F1, and F0 bits in the oscillation adjustment circuit.
Conversely, when such oscillation adjustment is to be made, an appropriate oscillation adjustment value can
be calculated by the equation below for writing to the oscillation adjustment circuit.
(1) When Oscillation Frequency (* 1) Is Higher Than Target Frequency (* 2) (Causing Time Count Gain)
Oscillation adjustment value (*3) = (Oscillation frequency - Target Frequency + 0.1)
Oscillation frequency
×
3.051
×
10
-6
(Oscillation Frequency – Target Frequency)
×
10 + 1
* 1) Oscillation frequency:
Frequency of clock pulse output from the 32KOUT pin at normal temperature in the manner described in
"14.2.2. Measurement of Oscillation Frequency".
* 2) Target frequency:
Desired frequency to be set. Generally, a 32.768-kHz crystal oscillator has such temperature
characteristics as to have the highest oscillation frequency at normal temperature. Consequently, the
crystal oscillator is recommended to have target frequency settings on the order of 32.768 to 32.76810 kHz
(+3.05ppm relative to 32.768 kHz). Note that the target frequency differs depending on the environment or
location where the equipment incorporating the RTC is expected to be operated.
* 3) Oscillation adjustment value:
Value that is to be finally written to the F0 to F6 bits in the Oscillation Adjustment Register and is represented
in 7-bit coded decimal notation.
(2) When Oscillation Frequency Is Equal To Target Frequency (Causing Time Count neither Gain nor Loss)
Oscillation adjustment value = 0, +1, -64, or –63
(3) When Oscillation Frequency Is Lower Than Target Frequency (Causing Time Count Loss)
Oscillation adjustment value = (Oscillation frequency - Target Frequency)
Oscillation frequency
×
3.051
×
10
-6
(Oscillation Frequency – Target Frequency)
×
10
Oscillation adjustment value calculations are exemplified below
A) For an oscillation frequency = 32768.85Hz and a target frequency = 32768.05Hz
Oscillation adjustment value = (32768.85 - 32768.05 + 0.1) / (32768.85
×
3.051
×
10
-6
)
(32768.85 - 32768.05)
×
10 + 1
= 9.001
9
In this instance, write the settings (F6,F5,F4,F3,F2,F1,F0)=(0,0,0,1,0,0,1) in the oscillation adjustment
register. Thus, an appropriate oscillation adjustment value in the presence of any time count gain
represents a distance from 01h.
B) For an oscillation frequency = 32763.95Hz and a target frequency = 32768.05Hz
Oscillation adjustment value = (32763.95 - 32768.05) / (32763.95
×
3.051
×
10
-6
)
(32763.95 - 32768.05)
×
10
= -41.015
-41
To represent an oscillation adjustment value of - 41 in 7-bit coded decimal notation, subtract 41 (29h)
from 128 (80h) to obtain 57h. In this instance, write the settings of (F6,F5,F4,F3,F2,F1,F0) =
(1,0,1,0,1,1,1) in the oscillation adjustment register. Thus, an appropriate oscillation adjustment value
in the presence of any time count loss represents a distance from 80h.
Oscillation adjustment involves an adjustment differential of approximately
±
1.5ppm from the target
frequency at normal temperature.
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