AD7607 datasheet(22/32 Pages) AD

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AD7608

Data Sheet

Rev. A | Page 22 of 32

TYPICAL CONNECTION DIAGRAM

Figure 40 shows the typical connection diagram for the AD7608.

There are four AVCC supply pins on the part, and each of the

four pins should be decoupled using a 100 nF capacitor at each

supply pin and a 10 µF capacitor at the supply source. The AD7608

can operate with the internal reference or an externally applied

reference. In this configuration, the AD7608 is configured to

operate with the internal reference. When using a single AD7608

device on the board, the REFIN/REFOUT pin should be

decoupled with a 10 µF capacitor. Refer to the Internal/External

Reference section when using an application with multiple

AD7608 devices. The REFCAPA and REFCAPB pins are

shorted together and decoupled with a 10 µF ceramic

capacitor.

The VDRIVE supply is connected to the same supply as the pro-

cessor. The VDRIVE voltage controls the voltage value of the

output logic signals. For layout, decoupling, and grounding

hints, see the Layout Guidelines section.

After supplies have been applied to the AD7608, apply a RESET

signal to the device to ensure it is configured for the correct

mode of operation.

POWER-DOWN MODES

There are two power-down modes available on the AD7608:

standby mode and shutdown mode. The

pin controls

whether the AD7608 is in normal mode or in one of the two

power-down modes.

STBY

The power-down mode is selected through the state of the

RANGE pin when the

STBYEE

pin is low. Table 7 shows the

configurations required to choose the desired power-down

mode. When the AD7608 is placed in standby mode, the

current consumption is 8 mA maximum and power-up time

is approximately 100 µs because the capacitor on the REFCAPA

and REFCAPB pins must charge up. In standby mode, the

on-chip reference and regulators remain powered up, and the

amplifiers and ADC core are powered down.

When the AD7608 is placed in shutdown mode, the current

consumption is 11 µA maximum and power-up time is approx-

imately 13 ms (external reference mode). In shutdown mode,

all circuitry is powered down. When the AD7608 is powered

up from shutdown mode, a RESET signal must be applied to

the AD7608 after the required power-up time has elapsed.

Table 7. Power-Down Mode Selection

Power-Down Mode

STBYEE

RANGE

Standby

Shutdown

AVCC

AGND

VDRIVE

REFIN/REFOUT

DB0 TO DB15

CONVST A, B

BUSY

RESET

AD7608

1µF

10µF

100nF

DIGITAL SUPPLY

VOLTAGE +2.3V TO +5V

ANALOG SUPPLY

VOLTAGE 5V1

EIGHT ANALOG

INPUTS V1 TO V8

PARALLEL

INTERFACE

1DECOUPLING SHOWN ON THE AVCC PIN APPLIES TO EACH AVCC PIN (PIN 1, PIN 37, PIN 38, PIN 48).

DECOUPLING CAPACITOR CAN BE SHARED BETWEEN AVCC PIN 37 AND PIN 38.

2DECOUPLING SHOWN ON THE REGCAP PIN APPLIES TO EACH REGCAP PIN (PIN 36, PIN 39).

REGCAP2

10µF

REFCAPA

REFCAPB

OS 2

OS 1

OS 0

OVERSAMPLING

100nF

PAR/SER SEL

STBY

REF SELECT

RANGE

REFGND

V1GND

V2GND

V3GND

V4GND

V5GND

V6GND

V7GND

V8GND

VDRIVE

Figure 40. Typical Connection Diagram

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