AD7328BRUZ(2004) View Datasheet(PDF) - Analog Devices

Part Name

Description

MFG CO.

AD7328BRUZ
(Rev.:2004)

8-Channel, Software-Selectable True Bipolar Input, 12-Bit Plus Sign ADC

Analog Devices 

Preliminary Technical Data

AD7328

Pin Functional Descriptions

CS 1

20 SCLK

DIN 2

19 DGND

DGND 3 AD7328 18 DOUT

AGND 4

17 VDRIVE

REFIN/OUT 5

VSS 6

VIN0 7

VIN1 8

TOP VIEW

(Not to

Scale)

16 VCC

15 VDD

14 VIN2

13 VIN3

VIN4 9

VIN5 10

12 VIN6

11 VIN7

Figure 3. AD7328 Pin Configuration TSSOP

Pin Mnemonic

SCLK

DOUT

CS

DIN

VDRIVE

DGND

AGND

REF IN/REFOUT

VCC

VDD

VSS

Vin0-Vin7

Table 4. AD7328 Pin Function Descriptions

Pin Number

20

18

1

2

17

3, 19

4

5

16

15

6

7,8,9,10,11,12,13,14

Description

Serial Clock. Logic Input. A serial clock input provides the SCLK used for accessing the data

from the AD7328. 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 three channel identification bits, followed by the

sign bit followed by the 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 AD7328 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.

Logic power supply input. The voltage supplied at this pin determines at what voltage the

interface will operate. This pin should be decoupled to DGND. The voltage at this pin may be

different to that at VCC but should never exceed VCC by more than 0.3V.

Digital Ground. Ground reference point for all digital circuitry on the AD7328. The DGND and

AGND voltages ideally should be at the same potential and must not be more than 0.3 V apart

even on a transient basis.

Analog Ground. Ground reference point for all analog circuitry on the AD7328. All analog input

signals and any external reference signal should be referred to this AGND voltage. The AGND

and DGND voltages ideally should be at the same potential and must not be more than 0.3 V

apart, even on a transient basis.

Reference Input/ Reference Output pin. The on-chip reference is available on this pin for use

external to the AD7328. Alternativley, the internal reference can be disabled and an external

reference applied to this input. On power up this is the default condition. The nominal internal

reference voltage is 2.5 V, which appears at the pin. A 470 nF capacitor should be placed on

the Reference pin. (See Reference Section)

Analog Supply Voltage, 2.7 V to 5.25 V. This is the supply voltage for the ADC core on the

AD7328. 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.

Analog input 0 through Analog Input 7. 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 bits, ADD2 through ADD0, in the control register. The inputs can be

configured as 8 Single-Ended Inputs, 4 True Differential Input pairs, 4 Pseudo differential

inputs or 7 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 registers. Inputs ranges of ±10V,

±5V, ±2.5V and 0 to 10V can be selected on each analog input channel. See Register section.

Rev. PrK | Page 8 of 24

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