AD7691
Data Sheet
Rev. C | Page 8 of 28
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
REF 1
VDD 2
IN+ 3
IN– 4
GND 5
VIO
10
SDI
9
SCK
8
SDO
7
CNV
6
AD7691
TOP VIEW
(Not to Scale)
0
614
6-
0
04
Figure 5. 10-Lead MSOP Pin Configuration
061
46-
005
1
REF
2
VDD
3
IN+
4
IN–
5
GND
10 VIO
9SDI
8SCK
7SDO
6 CNV
TOP VIEW
(Not to Scale)
AD7691
NOTES
1. THE EXPOSED PAD IS NOT CONNECTED
INTERNALLY. FOR INCREASED RELIABILITY OF
THE SOLDER JOINTS, IT IS RECOMMENDED THAT
THE PAD BE SOLDERED TO THE GROUND PLANE.
Figure 6. 10-Lead QFN (LFCSP) Pin Configuration
Table 8. Pin Function Descriptions
Pin No.
Mnemonic
Description
1
REF
AI
Reference Input Voltage. The REF range is from 0.5 V to VDD. It 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
Differential Positive Analog Input. Referenced to IN. The input range for IN+ is between 0 V and VREF,
centered about VREF/2 and must be driven 180° out of phase with IN.
4
IN
AI
Differential Negative Analog Input. Referenced to IN+. The input range for IN is between 0 V and VREF,
centered about VREF/2 and must be driven 180° out of phase with IN+.
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 of the part, either chain or CS mode. 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 18 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
Exposed Pad. The exposed pad is not connected internally. For increased reliability of the solder joints, it is
recommended that the pad be soldered to the ground plane.
1AI = analog input, DI = digital input, DO = digital output, and P = power.