AD7322 Analog Devices, AD7322 Datasheet - Page 22

• Manufacturer Part Number: AD7322
• Description: Software Selectable True Bipolar Input, 2-Channel, 12-Bit Plus Sign ADC
• Manufacturer: Analog Devices

Specifications of AD7322

• Resolution (bits): 13bit
• # Chan: 2
• Sample Rate: 1MSPS
• Interface: Ser,SPI
• Analog Input Type: Diff-Bip,Diff-Uni,SE-Uni
• Ain Range: Bip (Vref),Bip (Vref) x 2,Bip (Vref) x 4,Bip 10V,Bip 2.5V,Bip 5.0V,Uni (Vref) x 4,Uni 10V
• Adc Architecture: SAR
• Pkg Type: SOP

AD7322
CONTROL REGISTER
The control register is used to select the analog input channel,
analog input configuration, reference, coding, and power mode.
The control register is a write-only, 12-bit register. Data loaded
on the DIN line corresponds to the AD7322 configuration for
the next conversion. Data should be loaded into the control
MSB
15
Write
Table 9. Control Register Details
Bit
12, 11, 1
10
9, 8
7, 6
5
4
3, 2
Table 10. Analog Input Configuration Selection
Channel Address Bit
ADD0
0
1
14
Zero
13
Register Select
Mnemonic
Zero
ADD0
Mode 1,
Mode 0
PM1, PM0
Coding
Ref
Seq1, Seq2
V
Mode 1 = 1, Mode 0 = 1
IN
+
Not allowed
Not allowed
Description
These bits should contain 0 during each write to the control register.
This channel address bit is used to select the analog input channel for the next conversion if the
sequencer is not being used. If the sequencer is being used, this channel address bit is used to select the
final channel in the consecutive sequence (see Table 10).
These two mode bits are used to select the configuration of the two analog input pins, V
These bits are used in conjunction with the channel address bit. On the AD7322, the analog inputs can be
configured as single-ended inputs, true differential inputs, or pseudo differential inputs (see Table 10).
The power management bits are used to select different power mode options on the AD7322 (see Table 11).
This bit is used to select the type of output coding the AD7322 uses for the next conversion result. If
coding = 0, the output coding is twos complement. If coding = 1, the output coding is straight binary.
When operating in sequence mode, the output coding for each channel is the value written to the coding
bit during the last write to the control register.
The reference bit is used to enable or disable the internal reference. If Ref = 0, the external reference is
enabled and used for the next conversion, and the internal reference is disabled. If Ref = 1, the internal
reference is used for the next conversion. When operating in sequence mode, the reference used for each
channel is the value written to the Ref bit during the last write to the control register.
The Sequence 1 and Sequence 2 bits are used to control the operation of the sequencer (see Table 12).
12
Zero
V
IN
−
11
Zero
10
ADD0
V
V
V
1 Fully Differential Input
Mode 1 = 1, Mode 0 = 0
IN
IN
IN
0
0
+
Mode 1
9
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V
V
V
IN
IN
IN
8
Mode 0
1
1
−
register after the range register has been initialized. The bit
functions of the control register are shown in Table 9 (the
power-up status of all bits is 0).
The two analog input channels can be configured as one pseudo
differential analog input, one true differential input, or two
single-ended analog inputs (see Table 10).
7
PM1
V
V
V
1 Pseudo Differential Input
IN
IN
IN
Mode 1 = 0, Mode 0 =1
0
0
+
PM0
6
5
Coding
V
V
V
IN
IN
IN
1
1
−
4
Ref
3
Seq1
V
V
V
Mode 1 = 0, Mode 0 = 0
2 Single-Ended Inputs
IN
IN
IN
0
1
+
Seq2
2
IN
0 and V
V
AGND
AGND
1
Zero
IN
−
IN
1.
LSB
0
0