AD7322
Pin Functional Descriptions
CS
1
DIN 2
DGND 3
AGND 4
REFIN/OUT 5
VSS 6
VIN0 7
14 SCLK
13 DGND
Preliminary Technical Data
AD7322
12 DOUT
11 VDRIVE
TOP VIEW
10
8++
(Not to
9 VDD
Scale)
8 VIN1
Figure 3. AD7322 Pin Configuration TSSOP
Table 4. AD7324 Pin Function Descriptions
Pin
Mnemonic
SCLK
D
OUT
Pin
Number
14
12
Description
Serial Clock. Logic Input. A serial clock input provides the SCLK used for accessing the data
from the AD7322. This clock is also used as the clock source for the conversion process.
Serial Data Output. The conversion output data is supplied to this pin as a serial data stream.
The bits are clocked out on the falling edge of the SCLK input and 16 SCLKs are required to
access the data. The data stream consists of two leading zeros, one channel identification bit, a
Sign bit followed by 12 bits of conversion data. The data is provided MSB first. See the Serial
Interface section.
Chip Select. Active low logic input. This input provides the dual function of initiating
conversions on the AD7322 and frames the serial data transfer.
Data In. Data to be written to the on-chip registers is provided on this input and is clocked into
the register on the falling edge of SCLK. See Register section.
Analog Ground. Ground reference point for all analog circuitry on the AD7322. All analog input
signals and any external reference signal should be referred to this AGND voltage.
Reference Input/ Reference Output pin. When enabled the on-chip reference is available on
this pin for use external to the AD7322. Alternativley, the internal reference can be disabled
and an external reference applied to this input. When using the AD7322 with an external
reference, the internal reference must be disabled via the control register. The nominal
reference voltage is 2.5 V, which appears at the pin. The default on power up is for external
Reference operation. See
.
Analog Supply Voltage, 2.7 V to 5.25 V. This is the supply voltage for the ADC core on the
AD7322. This supply should be decoupled to AGND.
Positive power supply voltage. This is the positive supply voltage for the Analog Input section.
Negative power supply voltage. This is the negavtive supply voltage for the Analog Input
section.
This is the Digital Ground pin.
Logic Power Supply input. The voltage applied to this pin determines the operating voltge of
the sertial inteface.
Analog input 0 through Analog Input 1. The analog inputs are multiplexed into the on-chip
track-and-hold. The analog input channel for conversion is selected by programming the
channel address bit ADD0, in the control register. The inputs can be configured as 2 Single-
Ended Inputs, 1 True Differential Input pair, 1 Pseudo Differential inputs. The configuration of
the Analog inputs is selected by programming the Mode bits, Mode1 and Mode0, in the
Control Register. The input range on each input channel is controlled by programming the
range register. Inputs ranges of ±10V, ±5V, ±2.5V and 0 to 10V can be selected on each analog
input channel. See Register section.
CS
DIN
AGND
REF
IN/
REF
OUT
1
2
4
5
V
CC
V
DD
V
SS
DGND
V
DRIVE
Vin0-Vin1
10
9
6
3,13
11
7,8
Rev. PrE | Page 7 of 18
ATMEL [ ATMEL CORPORATION ]
