AD5675R datasheet(26/28 Pages) AD

26 / 28 page

Data Sheet

AD5676

Rev. B | Page 25 of 27

APPLICATIONS INFORMATION

POWER SUPPLY RECOMMENDATIONS

The AD5676 is typically powered by the following supplies: VDD =

3.3 V and VLOGIC = 1.8 V.

The ADP7118 can be used to power the VDD pin. The ADP160

can be used to power the VLOGIC pin. This setup is shown in

Figure 47. The ADP7118 can operate from input voltages up to

20 V. The ADP160 can operate from input voltages up to 5.5 V.

1.8V: VLOGIC

3.3V: VDD

5V INPUT

ADP160

LDO

ADP7118

LDO

Figure 47. Low Noise Power Solution for the AD5676

MICROPROCESSOR INTERFACING

Microprocessor interfacing to the AD5676 is via a serial bus

that uses a standard protocol that is compatible with DSP

processors and microcontrollers. The communications channel

requires a 3-wire or 4-wire interface consisting of a clock signal,

a data signal, and a synchronization signal. The AD5676 requires a

24-bit data-word with data valid on the rising edge of SYNC.

AD5676 TO ADSP-BF531 INTERFACE

The SPI interface of the AD5676 can easily connect to industry-

standard DSPs and microcontrollers. Figure 48 shows the

AD5676 connected to the Analog Devices, Inc. Blackfin® DSP.

The Blackfin has an integrated SPI port that can connect

directly to the SPI pins of the AD5676.

ADSP-BF531

SYNC

SPISELx

SCLK

SCK

SDI

MOSI

LDAC

PF9

RESET

PF8

AD5676

Figure 48. ADSP-BF531 Interface

AD5676 TO SPORT INTERFACE

The Analog Devices ADSP-BF527 has one SPORT serial port.

Figure 49 shows how a SPORT interface controls the AD5676.

ADSP-BF527

SYNC

SPORT_TFS

SCLK

SPORT_TSCK

SDI

SPORT_DTO

LDAC

GPIO0

RESET

GPIO1

AD5676

Figure 49. SPORT Interface

LAYOUT GUIDELINES

In any circuit where accuracy is important, careful consideration of

the power supply and ground return layout helps to ensure the

rated performance. Design the printed circuit board (PCB) on

which the AD5676 is mounted so that the AD5676 lies on the

analog plane.

The AD5676 must have ample supply bypassing of 10 μF in

parallel with 0.1 μF on each supply, located as close to the package

as possible, ideally right up against the device. The 10 μF

capacitors are the tantalum bead type. The 0.1 μF capacitor

must have low effective series resistance (ESR) and low effective

series inductance (ESI), such as the common ceramic types, which

provide a low impedance path to ground at high frequencies to

handle transient currents due to internal logic switching.

In systems where many devices are on one board, it is often useful

to provide some heat sinking capability to allow the power to

dissipate easily.

The GND plane on the device can be increased (as shown in

Figure 50) to provide a natural heat sinking effect.

AD5676

GND

PLANE

BOARD

Figure 50. Pad Connection to Board

AD5675R Datasheet(PDF) 26 Page - Analog Devices

AD5675R Datasheet(HTML) 26 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Datasheet Download

Link URL