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AD5673R/AD5677R

Data Sheet

Rev. 0 | Page 30 of 31

APPLICATIONS INFORMATION

POWER SUPPLY RECOMMENDATIONS

The AD5673R/AD5677R are 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. Figure 66 shows this

setup. The ADP7118 can operate from input voltages up to 20 V.

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

ADP160

LDO

ADP7118

LDO

INPUT

1.8V: VLOGIC

3.3V: VDD

Figure 66. Low Noise Power Solution for the AD5673R/AD5677R

MICROPROCESSOR INTERFACING

Microprocessor interfacing to the AD5673R/AD5677R uses a

serial bus with a standard protocol that is compatible with DSP

processors and microcontrollers. The communications channel

requires a 2-wire interface consisting of a clock signal and a

data signal.

AD5673R/AD5677R TO ADSP-BF531 INTERFACE

The I2C interface of the AD5673R/AD5677R is designed for

easy connection to industry-standard DSPs and microcontrollers.

Figure 67 shows the AD5673R/AD5677R connected to the Analog

Devices, Inc., ADSP-BF531 Blackfin® processor. The Blackfin

processor has an integrated I2C port that can be connected

directly to the I2C pins of the AD5673R/AD5677R.

ADSP-BF531

SCL

GPIO1

LDAC

PF9

RESET

PF8

SDA

GPIO2

AD5673R/

AD5677R

Figure 67. AD5673R/AD5677R to ADSP-BF531 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 PCB on which the AD5673R or

AD5677R is mounted so that the device lies on the analog plane.

The AD5673R/AD5677R 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 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 there are many devices 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 68) to provide a natural heat sinking effect.

GND

PLANE

BOARD

Figure 68. Pad Connection to Board

GALVANICALLY ISOLATED INTERFACE

In many process control applications, it is necessary to provide

an isolation barrier between the controller and the unit being

controlled to protect and isolate the controlling circuitry from

any hazardous common-mode voltages that may occur. iCoupler®

products from Analog Devices provide voltage isolation in excess

of 2.5 kV. The serial loading structure of the AD5673R/AD5677R

makes the devices ideal for isolated interfaces because the number

of interface lines is kept to a minimum. Figure 69 shows a

2-channel isolated interface to the AD5673R/AD5677R

using an ADuM1251. For further information, visit

www.analog.com/icoupler.

DECODE

SDA

CONTROLLER

ADuM12511

SCL

1ADDITIONAL PINS OMITTED FOR CLARITY.

ENCODE

SCL

SDA

ENCODE

DECODE

ENCODE

DECODE

Figure 69. Isolated Interface

AD5676 Datasheet(PDF) 30 Page - Analog Devices

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