Datasheet
AD7946
Rev. A | Page 7 of 24
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
04656-004
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
04656-005
REF
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 QFN (LFCSP) Pin Configuration
Table 6. Pin Function Descriptions
Pin No. Mnemonic Type
1
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).
1
AI = analog input, DI = digital input, DO = digital output, and P = power.