L2340 datasheet(3/11 Pages) LODEV

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DEVICES INCORPORATED

Special Arithmetic Functions

L2340

Digital Synthesizer

08/16/2000–LDS.2340-E

FIGURE 1A.INPUT FORMATS

14 13 12

14 213 212

31 30 29

*±2

0 2–1 2–2

–29 2–30 2–31

*±2

0 denotes two's complement sign or highest magnitude bit. Since phase angles are modulo 2π

and phase accumulator is modulo 2

32, this bit may be regarded as ±π.

Fract. Unsigned Mag./Two's Comp.

Integer Unsigned Magnitude

(RTP = 0)

FM, PM — Frequency Modulation,

Phase Modulation Control

FM and PM is the 2-bit Frequency

Modulation/Phase Modulation

Control that determines one of the

four modes shown in Table 2. When

full-scale is exceeded, the accumulator

will roll over correctly allowing

continuous phase accumulation

through 2

π radians.

OBIQ — Data Input/Output Format

Select

When OBIQ is HIGH, offset binary

format is selected. When OBIQ is

LOW, unsigned format is selected.

OEI — x-coordinate Data Output

Enable

When OEI is LOW, I15-0 is enabled for

data output. When OEI is HIGH, I15-0

is placed in a high-impedance state.

FIGURE 1B.OUTPUT FORMATS

14 13 12

14 213 212

14 13 12

14 213 212

Integer Unsigned Magnitude (OBIQ = 0)

15 14 13

NS 2

14 213

15 14 13

NS 2

14 213

Offset Binary (OBIQ = 1)

NS denotes negative sign. (i.e. '1' negates the number)

OEQ — y-coordinate Data Output

Enable

When OEQ is LOW, Q15-0 is enabled

for data output. When OEQ is HIGH,

Q15-0 is placed in a high-impedance

state.

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