AD7792 Analog Devices, AD7792 Datasheet - Page 19

• Manufacturer Part Number: AD7792
• Description: 3-Channel, Low Noise, Low Power, 16-Bit Sigma Delta ADC with On-Chip In-Amp and Reference
• Manufacturer: Analog Devices

Specifications of AD7792

• Resolution (bits): 16bit
• # Chan: 3
• Sample Rate: n/a
• Interface: Ser,SPI
• Analog Input Type: Diff-Uni
• Ain Range: (2Vref/PGA Gain) p-p
• Adc Architecture: Sigma-Delta
• Pkg Type: SOP

Table 18. IO Register Bit Designations
Bit Location
IO7 to IO4
IO3 to IO2
IO1 to IO0
OFFSET REGISTER
RS2, RS1, RS0 = 1, 1, 0; Power-On/Reset = 0x8000
(AD7792)/0x800000 (AD7793)
Each analog input channel has a dedicated offset register that
holds the offset calibration coefficient for the channel. This
register is 16 bits wide on the AD7792 and 24 bits wide on the
AD7793, and its power-on/reset value is 0x8000(00). The offset
register is used in conjunction with its associated full-scale
register to form a register pair. The power-on-reset value is
automatically overwritten if an internal or system zero-scale
calibration is initiated by the user. The offset register is a
read/write register. However, the AD7792/AD7793 must be
in idle mode or power-down mode when writing to the
offset register.
Bit Name
0
IEXCDIR1 to
IEXCDIR0
IEXCEN1 to
IEXCEN0
Description
These bits must be programmed with a Logic 0 for correct operation.
Direction of current sources select bits.
IEXCDIR1
0
0
1
1
These bits are used to enable and disable the current sources along with selecting the value of the
excitation currents.
IEXCEN1
0
0
1
1
IEXCDIR0
0
1
0
1
IEXCEN0
0
1
0
1
Rev. B | Page 19 of 32
Current Source Direction
Current Source IEXC1 connected to Pin IOUT1, Current Source IEXC2
connected to Pin IOUT2.
Current Source IEXC1 connected to Pin IOUT2, Current Source IEXC2
connected to Pin IOUT1.
Both current sources connected to Pin IOUT1. Permitted when the current
sources are set to 10 μA or 210 μA only.
Both current sources connected to Pin IOUT2. Permitted when the current
sources are set to 10 μA or 210 μA only.
Current Source Value
Excitation Current Disabled.
10 μA
210 μA
1 mA
FULL-SCALE REGISTER
RS2, RS1, RS0 = 1, 1, 1; Power-On/Reset = 0x5XXX
(AD7792)/0x5XXX00 (AD7793)
The full-scale register is a 16-bit register on the AD7792 and a
24-bit register on the AD7793. The full-scale register holds the
full-scale calibration coefficient for the ADC. The
AD7792/AD7793 have 3 full-scale registers, each channel
having a dedicated full-scale register. The full-scale registers are
read/write registers; however, when writing to the full-scale
registers, the ADC must be placed in power-down mode or idle
mode. These registers are configured on power-on with factory-
calibrated full-scale calibration coefficients, the calibration
being performed at gain = 1. Therefore, every device has
different default coefficients. The coefficients are different
depending on whether the internal reference or an external
reference is selected. The default value is automatically
overwritten if an internal or system full-scale calibration is
initiated by the user, or the full-scale register is written to.
AD7792/AD7793