Datasheet
Data Sheet AD7608
Rev. A | Page 11 of 32
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
AD7608
TOP VIEW
(Not to Scale)
64 63 62 61 60 59 58 57
V1GND
56 55 54 53 52 51 50 49
V5
V4
V6
V3
V2
V1
PIN 1
V7
V8
V2GND
V3GND
V4GND
V5GND
V6GND
V7GND
V8GND
DB13
DB12
DB11
DB14
V
DRIVE
DB1
17 18 19 20 21 22 23 24 25
AGND
26 27 28 29 30 31 32
DB2
DB3
DB4
DB5
DB6
DB7/D
OUT
A
DB9
DB10
DB8/D
OUT
B
AGND
AV
CC
1
3
4
FRSTDATA
7
6
5
OS 2
2
8
9
10
12
13
14
15
16
11
DB0
BUSY
CONVST B
CONVST A
RANGE
RESET
RD/SCLK
CS
PAR/SER SEL
OS 1
OS 0
STBY
DECOUPLING CAPACITOR PIN
DATA OUTPUT
POWER SUPPLY
ANALOG INPUT
GROUND PIN
DIGITAL OUTPUT
DIGITAL INPUT
REFERENCE INPUT/OUTPUT
DB15
REFIN/REFOUT
48
46
45
42
43
44
47
41
40
39
37
36
35
34
33
38
AGND
AV
CC
REFGND
REFCAPA
AGND
AGND
AGND
REFCAPB
REFGND
REGCAP
REGCAP
AV
CC
AV
CC
REF SELECT
08938-007
Figure 7. Pin Configuration
Table 6. Pin Function Descriptions
Pin No. Type12F11F
1
Mnemonic Description
1, 37, 38, 48
P
AV
CC
Analog Supply Voltage 4.75 V to 5.25 V. This supply voltage is applied to the internal front-end
amplifiers and to the ADC core. These supply pins should be decoupled to AGND.
2, 26, 35,
40, 41, 47
P AGND
Analog Ground. This pin is the ground reference point for all analog circuitry on the AD7608. All
analog input signals and external reference signals should be referred to these pins. All six of these
AGND pins should connect to the AGND plane of a system.
5, 4, 3
DI OS [2: 0]
Oversampling Mode Pins. Logic inputs. These inputs are used to select the oversampling ratio. OS 2
is the MSB control bit, while OS 0 is the LSB control bit. See the Digital Filter section for further
details on the oversampling mode of operation and Table 8 for oversampling bit decoding.
6
DI
AAPAR
EE
AA
/SER SEL Parallel/Serial Interface Selection Input. Logic input. If this pin is tied to a logic low, the parallel
interface is selected. If this pin is tied to a logic high, the serial interface is selected. In serial mode,
the
AARD
EE
AA
/SCLK pin functions as the serial clock input. The DB7/D
OUT
A and DB8/D
OUT
B pins function as
serial data outputs. When the serial interface is selected, DB[15:9] and DB[6:0] pins should be tied to
GND.
7 DI
AASTBY
EE
Standby Mode Input. This pin is used to place the AD7608 into one of two power-down modes: standby
mode or shutdown mode. The power-down mode entered depends on the state of the RANGE pin
as shown in Table 7. When in standby mode, all circuitry, except the on-chip reference regulators,
and regulator buffers, is powered down. When in shutdown mode, all circuitry is powered down.
8 DI RANGE
Analog Input Range Selection. Logic input. The polarity on this pin determines the input range of
the analog input channels. If this pin is tied to a logic high, the analog input range is ±10 V for all
channels. If this pin is tied to a logic low, the analog input range is ±5 V for all channels. A logic
change on this pin has an immediate effect on the analog input range. Changing this pin during
a conversion is not recommended. See the Analog Input section for more details.
9, 10
DI
CONVST A,
CONVST B
Conversion Start Input A, Conversion Start Input B. Logic inputs. These logic inputs are used to
initiate conversions on the analog input channels. For simultaneous sampling of all input channels,
CONVST A and CONVST B can be shorted together and a single convert start signal applied.
Alternatively, CONVST A can be used to initiate simultaneous sampling for V1, V2, V3, and V4, and
CONVST B can be used to initiate simultaneous sampling on the other analog inputs (V5, V6, V7, and
V8). This is only possible when oversampling is not switched on.
When the CONVST A or CONVST B pin transitions from low to high, the front-end track-and-hold
circuitry for their respective analog inputs is set to hold. This function allows a phase delay to be
created inherently between the sets of analog inputs.