CMX264 データシートの表示（PDF） - CML Microcircuits

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CMX264

Frequency Domain Split Band Scrambler

CML Microcircuits 

Frequency Domain Split Band Scrambler

Pre-emphasis Filters

Slope

Gain at 1kHz

De-emphasis Filters

Slope

Gain at 1kHz

Operating Split Points

Clear Mode Overall Signal Gain

Reset Circuit Delay

Serial Data Clock Frequency

Digital Inputs

Input Logic "1" Level

Input Logic "0" Level

Notes Min.

13

13

14

15

14

14

Typ.

6.0

0.7

-6.0

-0.7

1027

1276

1482

1966

0

3.0

1.0

80%

Max.

CMX264

Units

dB/Octave

dB

dB/Octave

dB

Hz

dB

ms

MHz

20%

VDD

VDD

Notes: 1. Not including any current drawn from the device pins by external circuitry.

2. This ignores the effects of pre-emphasis and de-emphasis, if selected.

3. Relative to a single tone at the MICIN pin. Because of the frequency inversion of the

scrambling process, the output frequency will not in general be equal to the input frequency.

However, the scramble signal output MICO will typically be within the limits given by Figures

3, 4, 5 or 6. The scrambled signal upper rolloff is defined by the filter TXUBOPF (Figure 7).

4. Filtering within the host equipment should ensure compliance with statutory transmission

requirements e.g. removal of a 4kHz SAT tone. See Figure 8 for a typical transmit filter which

would be used to accomplish this.

5 Not applicable within the region of the split point.

In transmit, the upperband is shifted upwards away from the lowerband so that there is a gap

in the scrambled spectrum. This avoids aliasing between the two bands in the recovered

audio. See Figures 3, 4, 5 and 6 which show these gaps for each split point.

6. An output may be de-activated by powersaving the whole device (D10 = 0) or by deselecting it

by means of the relevant control bit (D6, D7 or D8) or, for the RECO and EXTO outputs, by

setting the MUTERX pin to logic ‘1’

7. With a single tone at the relevant input pin (MICIN or RXIN).

8. This parameter specifies the level of any unwanted spurious tones relative to the expected

output tone, whether that wanted tone is frequency shifted or not. The unwanted tones may be

the result of carrier breakthrough, baseband breakthrough or other aliasing effects.

© 1999 Consumer Microcircuits Limited

16

D/CMX264/1

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