Datasheet

AD7609 Data Sheet
Rev. A | Page 24 of 36
TYPICAL CONNECTION DIAGRAM
Figure 41 shows the typical connection diagram for the
AD7609. There are four AV
CC
supply pins on the part that
can be tied together and decoupled using a 100 nF capacitor at
each supply pin and a 10 µF capacitor at the supply source. The
AD7609 can operate with the internal reference or an externally
applied reference. In this configuration, the AD7609 is config-
ured to operate with the internal reference. When using a single
AD7609 device on the board, the REFIN/REFOUT pin should
be decoupled with a 10 µF capacitor. In an application with
multiple AD7609 devices, see the Internal/External Reference
section. The REFCAPA and REFCAPB pins are shorted together
and decoupled with a 10 µF ceramic capacitor.
The V
DRIVE
supply is connected to the same supply as the pro-
cessor. The voltage on V
DRIVE
controls the voltage value of the
output logic signals. For layout, decoupling, and grounding
hints, see the Layout Guidelines section.
After supplies are applied to the AD7609, a reset should be
applied to the AD7609 to ensure that it is configured for the
correct mode of operation.
POWER-DOWN MODES
There are two power-down modes available on the AD7609.
The
STBY
pin controls whether the AD7609 is in normal mode
or one of the two power-down modes. The two power-down
modes available are standby mode and shutdown mode. The
power-down mode is selected through the state of the RANGE
pin when the
STBY
pin is low. Table 8 shows the configurations
required to choose the desired power-down mode. When the
AD7609 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/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 AD7609 is placed in shutdown
mode, the current consumption is 11 µA maximum and power
up time is about 13 ms. In shutdown mode, all circuitry
is powered down. When the AD7609 is powered up from
shutdown mode, a reset signal must be applied to the AD7609
after the required power-up time has elapsed.
Table 8. Power-Down Mode Selection
Power-Down Mode
STBY
RANGE
Standby 0 1
Shutdown 0 0
AV
CC
AGND
V
DRIVE
+
REFIN/REFOUT
DB0 TO DB15
CONVST A, B
CS
RD
BUSY
RESET
AD7609
1µF
10µF
100nF
DIGITAL SUPPLY
VOLTAGE +2.3V TO +5V
ANALOG SUPPLY
VOLTAGE 5V
1
EIGHT DIFFERENTIAL
ANALOG INPUT PAIRS
PARALLEL
INTERFACE
1
DECOUPLING SHOWN ON THE AV
CC
PIN APPLIES TO EACH AV
CC
PIN (PIN 1, PIN 37, PIN 38, PIN 48).
DECOUPLING CAPACITOR CAN BE SHARED BETWEEN AV
CC
PIN 37 AND PIN 38.
2
DECOUPLING SHOWN ON THE REGCAP PIN APPLIES TO EACH REGCAP PIN (PIN 36, PIN 39).
REGCAP
2
+
10µF
REFCAPA
REFCAPB
OS 2
OS 1
OS 0
OVERSAMPLING
100nF
V1+
PAR/SER SEL
STBY
REF SELECT
RANGE
V2+
V3+
V4+
V5+
V6+
V7+
V8+
REFGND
V1–
V2–
V3–
V4–
V5–
V6–
V7–
V8–
V
DRIVE
V
DRIVE
MICROPROCESSOR/
MICROCONVERTER/
DSP
09760-038
Figure 41. Typical Connection Diagram