AD7788/AD7789

Rev. B | Page 9 of 20

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

AD7788/

AD7789

TOP VIEW

(Not to Scale)

DIN

DOUT/RDY

GND

REFIN(–)

10

9

8

7

6

Figure 5. Pin Configuration

Table 6. Pin Function Descriptions

Pin No.

Mnemonic

Description

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

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/RDY used to interface with the device.

3

AIN(+)

Analog Input. AIN(+) is the positive terminal of the fully differential analog input.

4

AIN(−)

Analog Input. AIN(–) is the negative terminal of the fully differential analog input.

5

REFIN(+)

6

REFIN(−)

7

GND

Ground Reference Point.

8

Supply Voltage. 3 V or 5 V nominal.

9

DOUT/RDY

The DOUT/RDY falling edge can be used as an interrupt to a processor, indicating that valid data is available.

With an external serial clock, the data can be read using the DOUT/RDY pin. With CS low, the data/control word

information is placed on the DOUT/RDY pin on the SCLK falling edge and is valid on the SCLK rising edge.

The end of a conversion is also indicated by the RDY bit in the status register. When CS is high, the DOUT/RDY

pin is three-stated, but the RDY bit remains active.

10

DIN

Serial Data Input to the Input Shift Register on the ADC. Data in this shift register is transferred to the control

registers within the ADC; the register selection bits of the communications register identify the appropriate

register.