AD7940

Rev. A | Page 7 of 20

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

CS

SDATA

SCLK

6

5

4

GND

2

AD7940

TOP VIEW

(Not to Scale)

SOT-23

Figure 3. SOT-23 Pin Configuration

NC = NO CONNECT

AD7490

MSOP

TOP VIEW

(Not to Scale)

GND

2

GND

3

CS

SDATA

NC

SCLK

8

7

6

5

Figure 4. MSOP Pin Configuration

Table 5. Pin Function Descriptions

Pin No.

SOT-23

Pin No.

MSOP

Mnemonic

Function

1

1

V

DD

Power Supply Input. The V

2

2, 3

GND

Analog Ground. Ground reference point for all circuitry on the AD7940. All analog input signals should

be referred to this GND voltage.

3

4

V

IN

Analog Input. Single-ended analog input channel. The input range is 0 V to V

4

5

SCLK

Serial Clock. Logic input. SCLK provides the serial clock for accessing data from this part. This clock

input is also used as the clock source for the AD7940's conversion process.

5

7

SDATA

Data Out. Logic output. The conversion result from the AD7940 is provided on this output as a serial

data stream. The bits are clocked out on the falling edge of the SCLK input. The data stream from the

AD7940 consists of two leading zeros followed by 14 bits of conversion data that are provided MSB

first. This will be followed by four trailing zeroes if CS is held low for a total of 24 SCLK cycles. See the

Serial Interface section.

6

8

CS

Chip Select. Active low logic input. This input provides the dual function of initiating conversions on

the AD7940 and framing the serial data transfer.

N/A

6

NC

No Connect. This pin should be left unconnected.