MC145026D データシートの表示（PDF） - Freescale Semiconductor

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MC145026D

Encoder and Decoder Pairs CMOS

Freescale Semiconductor 

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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