Preliminary Technical Data

AD7792/AD7793

REV.PrF 6/04 | Page 9

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

512

AIN1(+)

GND

6

7

8

11

10

9

AIN1(-)

AIN2(+)

AIN2(-)

IOUT2

REFIN(-)/AIN3(-)

REFIN(+)/AIN3(+)

3

4

14

13

CS

IOUT1

DVDD

AVDD

1

2

16

15

SCLK

CLK

DIN

DOUT/RDY

AD7792/

AD7793

TOP VIEW

(Not To Scale)

Figure 5. Pin Configuration

Table 4. Pin Function Descriptions

Pin

No.

Mnemonic

Function

1

SCLK

Serial Clock Input for Data Transfers to and from the ADC. The SCLK has a Schmitt-triggered input, making the

interface suitable for opto-isolated applications. The serial clock can be continuous with all data transmitted in

a continuous train of pulses. Alternatively, it can be a noncontinuous clock with the information being trans-

mitted to or from the ADC in smaller batches of data.

2

CLK

Clock In/Clock Out. The internal clock can be made available at this pin. Alternatively, the internal clock can

be disabled and the ADC can be driven by an external clock. This allows several ADCs to be driven from a

common clock, allowing simultaneous conversions to be performed.

3

CS

Chip Select Input. This is an active low logic input used to select the ADC. CS can be used to select the ADC in

systems with more than one device on the serial bus or as a frame synchronization signal in communicating

with the device. CS can be hardwired low, allowing the ADC to operate in 3-wire mode with SCLK, DIN, and

DOUT used to interface with the device.

4

IOUT1

Output of Internal Excitation Current Source.

The internal excitation current source can be made available at this pin. The excitation current source is

programmable so that the current can be 10 uA, 200 uA or 1 mA. Either IEXC1 or IEXC2 can be switched to this

output.

5

AIN1(+)

Analog Input. AIN1(+) is the positive terminal of the differential analog input pair AIN1(+)/AIN1(-).

6

AIN1(-)

Analog Input. AIN1(–) is the negative terminal of the differential analog input pair AIN1(+)/AIN1(-).

7

AIN2(+)

Analog Input. AIN2(+) is the positive terminal of the differential analog input pair AIN2(+)/AIN2(-).

8

AIN2(-)

Analog Input. AIN2(–) is the negative terminal of the differential analog input pair AIN2(+)/AIN2(-).

9

REFIN(+)/AIN3(+)

Positive Reference Input/Analog Input.

and GND + 0.1 V. The nominal reference voltage (REFIN(+) – REFIN(–)) is 2.5 V, but the part functions with a

Alernatively, this pin can function as AIN3(+) where AIN3(+) is the positive terminal of the differential analog

input pair AIN3(+)/AIN3(-).

10

REFIN(-)/AIN3(-)

Negative Reference Input/Analog Input.

REFIN(-) is the negative reference input for REFIN. This reference input can lie anywhere between GND and

This pin also functions as AIN3(-) which is the negative terminal of the differential analog input pair

AIN3(+)/AIN3(-).

11

IOUT2

Output of Internal Excitation Current Source.

The internal excitation current source can be made available at this pin. The excitation current source is

programmable so that the current can be 10 uA, 200 uA or 1 mA. Either IEXC1 or IEXC2 can be switched to this

output

12

GND

Ground Reference Point.

13

Supply Voltage, 2.7 V to 5.25 V.

14

Digital Interface Supply Voltage. The logic levels for the serial interface pins are related to this supply, which is