AD7631(2011) View Datasheet(PDF) - Analog Devices
Part Name
Description
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AD7631 Datasheet PDF : 32 Pages
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AD7631
Pin No.
37
38
39
40
41
43
45
46
47
48
49
Mnemonic
REF
REFGND
IN−
VCC
VEE
IN+
TEMP
REFBUFIN
PDREF
PDBUF
EPAD3
Type1
AO/I
AI
AI
P
P
AI
AO
AI
DI
DI
NC
Description
Reference Input/Output. When PDREF/PDBUF = low, the internal reference and buffer are enabled
producing 5 V on this pin. When PDREF/PDBUF = high, the internal reference and buffer are disabled,
allowing an externally supplied voltage reference up to AVDD volts. Decoupling with at least a 22 μF
capacitor is required with or without the internal reference and buffer. See the Voltage Reference
Input/Output section.
Reference Input Analog Ground. Connected to analog ground plane.
Analog Input. Referenced to IN+.
In the 0 V to 5 V input range, IN− is between 0 V and VREF V centered about VREF/2. In the 0 V to 10 V
range, IN− is between 0 V and 2 VREF V centered about VREF.
In the ±5 V and ±10 V ranges, IN− is true bipolar up to ±2 VREF V (±5 V range) or ±4 VREF V (±10 V range)
and centered about 0 V.
In all ranges, IN− must be driven 180° out of phase with IN+.
High Voltage Positive Supply. Normally +7 V to +15 V.
High Voltage Negative Supply. Normally 0 V to −15 V (0 V in unipolar ranges).
Analog Input. Referenced to IN−.
In the 0 V to 5 V input range, IN+ is between 0 V and VREF V centered about VREF/2. In the 0 V to 10 V
range, IN+ is between 0 V and 2 VREF V centered about VREF.
In the ±5 V and ±10 V ranges, IN+ is true bipolar up to ±2 VREF V (±5 V range) or ±4 VREF V (±10 V range)
and centered about 0 V.
In all ranges, IN+ must be driven 180° out of phase with IN−.
Temperature Sensor Analog Output. When the internal reference is enabled (PDREF = PDBUF = low),
this pin outputs a voltage proportional to the temperature of the AD7631. See the Voltage Reference
Input/Output section.
Reference Buffer Input. When using an external reference with the internal reference buffer (PDBUF = low,
PDREF = high), applying 2.5 V on this pin produces 5 V on the REF pin. See the Voltage Reference
Input/Output section.
Internal Reference Power-Down Input.
When low, the internal reference is enabled.
When high, the internal reference is powered down, and an external reference must be used.
Internal Reference Buffer Power-Down Input.
When low, the buffer is enabled (must be low when using internal reference).
When high, the buffer is powered down.
Exposed Pad. The exposed pad is not connected internally. It is recommended that the pad be soldered
to VEE.
1 AI = analog input; AI/O = bidirectional analog; AO = analog output; DI = digital input; DI/O = bidirectional digital; DO = digital output; P = power, NC = no internal
connection.
2 In serial configuration mode (MODE[1:0] = 3, HW/SW = low), this input is programmed with the serial configuration register and this pin is a don’t care. See the
Hardware Configuration section and the Software Configuraion section.
3 LFCSP_VQ package only.
Table 7. Data Bus Interface Definition
MODE MODE1 MODE0 D0/OB/2C
0
0
0
R[0]
1
0
1
OB/2C
1
0
1
OB/2C
2
1
0
OB/2C
2
1
0
OB/2C
2
1
0
OB/2C
2
1
0
OB/2C
3
1
1
OB/2C
D1/A0 D2/A1
R[1] R[2]
A0 = 0 R[2]
A0 = 1 R[0]
A0 = 0 A1 = 0
A0 = 0 A1 = 1
A0 = 1 A1 = 0
A0 = 1 A1 = 1
All High-Z
D[3] D[4:9]
R[3] R[4:9]
R[3] R[4:9]
R[1]
All High-Z
All High-Z
All High-Z
All High-Z
D[10:11] D[12:15] D[16:17]
R[10:11] R[12:15] R[16:17]
R[10:11] R[12:15] R[16:17]
All zeros
R[10:11] R[12:15] R[16:17]
R[2:3]
R[4:7]
R[8:9]
R[0:1]
All zeros
All zeros
R[0:1]
Serial interface
Description
18-bit parallel
16-bit high word
16-bit low word
8-bit high byte
8-bit midbyte
8-bit low byte
8-bit low byte
Serial interface
Rev. A | Page 11 of 32
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