MC145028 데이터 시트보기 (PDF) - Freescale Semiconductor
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MC145028 Datasheet PDF : 20 Pages
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RS
11
CTC
RTC
12
13
INTERNAL
ENABLE
This oscillator operates at a frequency determined by the
external RC network; i.e.,
f≈
1
(Hz)
2.3 RTC CTC′
for 1 kHz ≤ f ≤ 400 kHz
where: CTC′ = CTC + Clayout + 12 pF
RS ≈ 2 RTC
RS ≥ 20 k
RTC ≥ 10 k
400 pF < CTC < 15 µF
The value for RS should be chosen to be ≥ 2 times RTC. This range ensures
that current through RS is insignificant compared to current through RTC. The
upper limit for RS must ensure that RS x 5 pF (input capacitance) is small com-
pared to RTC x CTC.
For frequencies outside the indicated range, the formula is less accurate.
The minimum recommended oscillation frequency of this circuit is 1 kHz. Sus-
ceptibility to externally induced noise signals may occur for frequencies below
1 kHz and/or when resistors utilized are greater than 1 MΩ.
Figure 9. Encoder Oscillator Information
TE
ENCODER
OSCILLATOR
(PIN 12)
Dout
(PIN 15)
PWmin
VT
(PIN 11)
DATA OUTPUTS
ENCODER
2 WORD TRANSMISSION
CONTINUOUS TRANSMISSION
1ST
DIGIT
9TH
DIGIT
HIGH
OPEN
LOW
1ST WORD
ENCODING SEQUENCE
DECODER
1ST
DIGIT
9TH
DIGIT
2ND WORD
1.1 (R2C2)
Figure 10. Timing Diagram
MC145026•MC145027•MC145028•SC41343•SC41344
10
MOTOROLA
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