AD7691-EP Enhanced Product
Rev. A | Page 8 of 13
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-EP
TOP VIEW
(Not to Scale)
12156-004
Figure 5. 10-Lead MSOP Pin Configuration
Table 7. Pin Function Descriptions
1 REF AI Reference Input Voltage. The REF range is from 0.5 V to VDD. It is referred to the GND pin. Decouple this
pin closely 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 V
REF
,
centered about V
REF
/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 V
REF
,
centered about V
REF
/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 device, either chain mode 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.
Serial Data Output. The conversion result is output on this pin. It is synchronized to SCK.
Serial Data Clock Input. When the device is selected, the conversion result is shifted out by this clock.
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).
1
AI = analog input, DI = digital input, DO = digital output, and P = power.
