AD1865R View Datasheet(PDF) - Analog Devices

Part Name

Description

MFG CO.

AD1865R

Complete Dual 18-Bit 16 X 3 FS Audio DAC

Analog Devices 

AD1865

MULTICHANNEL DIGITAL KEYBOARD DESIGN

Figure 11 illustrates how to cascade AD1865’s to add multiple

voices to an electronic musical instrument. In this example, the

data and clock signals are shared between all six DACs. As the

data representing an output for a specific voice is loaded, the ap-

propriate DAC is updated. For example, after the 18-bits repre-

senting the next output value for Voice 4 is clocked out on the

data line, then “Voice 4 Load” is pulled low. This produces a

new output for Voice 4. Furthermore, all voices can be returned

to the same output by pulling all six load signals low.

In this application, the advantages of choosing the AD1865 are

clear. Its flexible digital interface allows the clock and data to be

shared among all DACs. This reduces PC board area require-

ments and also simplifies the actual layout of the board. The low

power requirements of the AD1865 (approximately 225 mW) is

an advantage in a multiple DAC system where any power advan-

tage is multiplied by the number of DACs used. The AD1865

requires no external components, simplifying the design, reduc-

ing the total number of components required and enhancing

reliability.

VOICE 1

OUTPUT

+5V ANALOG

SUPPLY

–5V ANALOG

SUPPLY

ANALOG

COMMON

VOICE 1 LOAD

VOICE 2 LOAD

VOICE 3 LOAD

DATA

CLOCK

VOICE 2 VOICE 3

OUTPUT OUTPUT

VOICE 4 VOICE 5

OUTPUT OUTPUT

VOICE 6

OUTPUT

AD1865

1 –VS

+VS 24

2 TRIM TRIM 23

3 MSB

4 IOUT

MSB 22

IOUT 21

5 AGND AGND 20

6 SJ

7 RF

8 VOUT

9 +VL

10 DR

SJ 19

RF 18

VOUT 17

NC 16

DL 15

11 LR

LL 14

12 CLK

DGND 13

AD1865

1 –VS

+VS 24

2 TRIM

TRIM 23

3 MSB

4 IOUT

MSB 22

IOUT 21

5 AGND AGND 20

6 SJ

SJ 19

7 RF

8 VOUT

9 +VL

10 DR

RF 18

VOUT 17

NC 16

DL 15

11 LR

LL 14

12 CLK

DGND 13

AD1865

1 –VS

+VS 24

2 TRIM TRIM 23

3 MSB

4 IOUT

MSB 22

IOUT 21

5 AGND AGND 20

6 SJ

SJ 19

7 RF

8 VOUT

9 +VL

10 DR

RF 18

VOUT 17

NC 16

DL 15

11 LR

LL 14

12 CLK DGND 13

Figure 11. Cascaded AD1865s in a Multichannel Keyboard Instrument

VOICE 6 LOAD

VOICE 5 LOAD

VOICE 4 LOAD

DIGITAL COMMON

+5V DIGITAL SUPPLY

REV. 0

–9–

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