AD7322BRU 查看數據表（PDF） - Atmel Corporation
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AD7322BRU Datasheet PDF : 18 Pages
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AD7322
Preliminary Technical Data
AD7322 REGISTERS
The AD7322 has two-programmable registers, the Control Register and the Range Register. These registers are write only registers.
Addressing these Registers
A serial transfer on the AD7322 consists of 16 SCLK cycles. The three MSBs on the DIN line during each 16 SCLK transfer are decoded to
determine which register is addressed. The three MSBs consists of the Write bit, ZERO bit and a Register Select bit. The Register Select bit
is used to determine which of the Two on-board registers is selected. The Write bit will determine if the Data on the DIN line following
the Register select bit is loaded into the addressed register or not. If the Write bit is 1 the bits will be loaded into the register addressed by
the Register Select bit. If the Write Bit is a 0 the data on the DIN will not be loaded into any register and both registers will remain
unchanged.
Table 7. Decoding Register Select bit and Write bit.
Write
ZERO
Register Select2 Comment
0
0
0
Data on the DIN line during this serial transfer will be ignored. Register contents will
remain unchanged.
1
0
0
This combination selects the Control Register. The subsequent 12 bits will be loaded into
the Control Register.
1
0
1
This combination selects the Range Register. The subsequent 8 bits will be loaded into
the Range Register.
CONTROL REGISTER
The Control Register is used to select the Analog Input configuration, Reference, Coding, Power mode etc. 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 Register after the Range Register has been initialized. The bit functions of the Control Register are outlined in
Table 8.
Control Register (The Power-up status of all bits is 0)
Table 8. Control Register
MSB DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1
Write
ZERO
Register
Select
ZERO
ZERO
ADD0
Mode1 Mode0
PM1
PM0 Coding
Ref
Seq1 Seq2 ZERO
Bit
Mnemonic Comment
10
ADD0
ThIs Channel Address bit is used to select the analog input channel for the next conversion if the Sequencer is
not being used.
9, 8
Mode1,
These two mode bits are used to select the configuation on the two analog Input Pins. They are used in
Mode0
conjunction with the channel Address bit. On the AD7322 the analog inputs can be configured as either 2
Single Ended Inputs, 1 Fully Differential Input, 1 Pseudo Differential input. See Table 9.
7,6
PM1, PM0
Power Management Bits. These two bits are used to select different power mode options on the AD7322. See
Table 10.
5
Coding
This bit is used to select the type of output coding the AD7322 will use for the next conversion result. If the
Coding = 0 then the output coding will be 2s Complement. If Coding = 1, then the output coding will be
Straight Binary. When operating in Sequence mode the output coding for each channel will be the value
written to the coding bit during the last write to the Control Register.
4
Ref
Reference bit. This bit is used to enable or disable the internal reference. If this Ref = 0 then the Internal
Reference will be enable and used for the next conversion. If ref = 1 then an external Reference will be used
for the next conversion and the internal reference will be disabled. When operating in Sequence mode the
Rev. PrE | Page 12 of 18
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