Data Sheet

AD7946

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

REF

VDD

IN+

IN–

GND

VIO

SDI

SCK

SDO

CNV

1

2

3

4

5

10

9

8

7

6

AD7946

TOP VIEW

(Not to Scale)

Figure 4. 10-Lead MSOP Pin Configuration

REF

NOTES

1. EXPOSED PAD. THE EXPOSED PAD MUST

BE CONNECTED TO GROUND. THIS

CONNECTION IS NOT REQUIRED TO MEET

ELECTRICAL PERFORMANCES.

VDD

IN+

IN–

GND

VIO

SDI

SCK

SDO

CNV

AD7946

TOP VIEW

(Not to Scale)

1

2

3

4

5

10

9

8

7

6

Figure 5. 10-Lead LFCSP Pin Configuration

Table 6. Pin Function Descriptions

Pin No.

Mnemonic

Type1

Description

1

REF

AI

Reference Input Voltage. The REF range is from 0.5 V to VDD, and is referred to the GND pin. This pin

should be decoupled closely to the pin with a 10 µF capacitor.

2

VDD

P

Power Supply.

3

IN+

AI

Analog Input. It is referred to IN−. The voltage range, that is, the difference between IN+ and IN−,

is 0 V to REF.

4

IN−

AI

Analog Input Ground Sense. Connect to the analog ground plane or to a remote sense ground.

5

GND

P

Power Supply Ground.

6

CNV

DI

Convert Input. This input has multiple functions. On its leading edge, it initiates the conversions and

selects the interface mode, chain, or CS. In CS mode, it enables the SDO pin when low. In chain mode,

the data should be read when CNV is high.

7

SDO

DO

Serial Data Output. The conversion result is output on this pin. It is synchronized to SCK.

8

SCK

DI

Serial Data Clock Input. When the part is selected, the conversion result is shifted out by this clock.

9

SDI

DI

Serial Data Input. This input provides multiple features. It selects the interface mode of the

ADC as follows:

Chain mode is selected if SDI is low during the CNV rising edge. In this mode, SDI is used as a data

input to daisy-chain the conversion results of two or more ADCs onto a single SDO line. The digital

data level on SDI is output on SDO with a delay of 14 SCK cycles.

CS mode is selected if SDI is high during the CNV rising edge. In this mode, either SDI or CNV can

enable the serial output signals when low, and if SDI or CNV is low when the conversion is complete,

the BUSY indicator feature is enabled.

10

VIO

P

Input/Output Interface Digital Power. Nominally at the same supply as the host interface (1.8 V, 2.5 V,

3 V, or 5 V).

EPAD

N/A

Exposed Pad. The exposed pad must be connected to ground. This connection is not required to meet

electrical performances.

1

AI = analog input, DI = digital input, DO = digital output, and P = power.

Rev. B | Page 7 of 24