Datasheet

AD7682/AD7689 Data Sheet
Rev. D | Page 10 of 32
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
PIN 1
INDICATOR
1VDD
2REF
NOTES
1. NC = NO CONNECT.
2
. THE EXPOSED PAD IS NOT CONNECTED
INTERNALLY. FOR INCREASED
RELIABILITY OF THE SOLDER JOINTS, I
T
IS RECOMMENDED THAT THE PAD BE
SOLDERED TO THE SYSTEM
GROUND PLANE.
3REFIN
4GND
5GND
13 SCK
14 SDO
15 VIO
12 DIN
11 CNV
6
NC
7
IN2
8
NC
01
COM
9
IN3
81
IN1
91
NC
02
VDD
71
NC
61
IN0
TOP VIEW
(Not to Scale)
AD7682
07353-004
Figure 4. AD7682 Pin Configuration
PIN 1
INDICATOR
1VDD
2REF
3REFIN
4GND
5GND
13 SCK
14 SDO
15 VIO
12 DIN
11 CNV
6
IN4
7
IN5
8
IN6
01
COM
9
IN7
81
IN2
91
IN3
02
VDD
71
IN1
61
IN0
TOP VIEW
(Not to Scale)
AD7689
07353-005
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 SYSTEM
GROUND PLANE.
Figure 5. AD7689 Pin Configuration
Table 7. Pin Function Descriptions
Pin No.
AD7682
Mnemonic
AD7689
Mnemonic Type
1
Description
1, 20 VDD VDD P
Power Supply. Nominally 2.5 V to 5.5 V when using an external reference and decoupled
with 10 F and 100 nF capacitors.
When using the internal reference for a2.5 V output, the minimum should be 3.0 V.
When using the internal reference for 4.096 V output, the minimum should be 4.6 V.
2 REF REF AI/O
Reference Input/Output. See the Voltage Reference Output/Input section.
When the internal reference is enabled, this pin produces a selectable system reference of
2.5 V or 4.096 V.
When the internal reference is disabled and the buffer is enabled, REF produces a
buffered version of the voltage present on the REFIN pin (VDD − 0.5 V maximum), which
is useful when using low cost, low power references.
For improved drift performance, connect a precision reference to REF (0.5 V to VDD).
For any reference method, this pin needs decoupling with an external 10 F capacitor
connected as close to REF as possible. See the Reference Decoupling section.
3 REFIN REFIN AI/O
Internal Reference Output/Reference Buffer Input. See the Voltage Reference
Output/Input section.
When using the internal reference, the internal unbuffered reference voltage is present
and needs decoupling with a 0.1 F capacitor.
When using the internal reference buffer, apply a source between 0.5 V and (VDD − 0.5 V)
that is buffered to the REF pin, as described in the REF pin description.
4, 5 GND GND P Power Supply Ground.
6 NC IN4 AI
AD7682: no connection.
AD7689: Analog Input Channel 4.
7 IN2 IN5 AI
AD7682: Analog Input Channel 2.
AD7689: Analog Input Channel 5.
8 NC IN6 AI
AD7682: no connection.
AD7689: Analog Input Channel 6.
9 IN3 IN7 AI
AD7682: Analog Input Channel 3.
AD7689: Analog Input Channel 7.
10 COM COM AI
Common Channel Input. All input channels, IN[7:0], can be referenced to a common-
mode point of 0 V or V
REF
/2 V.
11 CNV CNV DI
Conversion Input. On the rising edge, CNV initiates the conversion. During conversion, if
CNV is held low, the busy indictor is enabled.
12 DIN DIN DI
Data Input. This input is used for writing to the 14-bit configuration register. The
configuration register can be written to during and after conversion.
13 SCK SCK DI
Serial Data Clock Input. This input is used to clock out the data on SDO and clock in data
on DIN in an MSB first fashion.