AD7796 Analog Devices, AD7796 Datasheet - Page 14

• Manufacturer Part Number: AD7796
• Description: Low Power 16-Bit Sigma-Delta A/D Converter for Bridge Sensors
• Manufacturer: Analog Devices

Specifications of AD7796

• Resolution (bits): 16bit
• # Chan: 1
• Sample Rate: n/a
• Interface: Ser,SPI
• Analog Input Type: Diff-Bip,Diff-Uni
• Ain Range: ± (Vref/128)
• Adc Architecture: Sigma-Delta
• Pkg Type: SOP

AD7796/AD7797
CONFIGURATION REGISTER
RS2, RS1, RS0 = 0, 1, 0; Power-On/Reset = 0x0710
The configuration register is a 16-bit read/write register. This register is used to configure the ADC for unipolar or bipolar mode, enable
or disable the burnout currents, and select the analog input channel. Table 15 outlines the bit designations for the configuration register.
CON0 through CON15 indicate the bit locations, with CON denoting that the bits are in the configuration register. CON15 denotes the
first bit of the data stream. The number in brackets indicates the power-on/reset default status of that bit.
MSB
CON15
0(0)
Table 15. Configuration Register Bit Designations
Bit Location
CON15 to CON14
CON13
CON12
CON11
CON10 to CON8
CON7 to CON5
CON4
CON3
CON2 to CON0
DATA REGISTER
RS2, RS1, RS0 = 0, 1, 1; Power-On/Reset = 0x0000 (AD7796)/0x000000 (AD7797)
The conversion result from the ADC is stored in this data register. This is a read-only register. On completion of a read operation from
this register, the RDY bit/pin is set.
ID REGISTER
RS2, RS1, RS0 = 1, 0, 0; Power-On/Reset = 0x5A (AD7796)/0x5B (AD7797)
The identification number for the AD7796/AD7797 is stored in the ID register. This is a read-only register.
CON14
0(0)
CON13
BO(0)
Bit Name
0
BO
U/B
0
1
0
1
0
CH2 to CH0
CON12
U/ B (0)
Description
These bits must be programmed with a Logic 0 for correct operation.
Burnout Current Enable Bit. When this bit is set to 1 by the user, the 100 nA current sources in the signal
path are enabled. When BO = 0, the burnout currents are disabled.
Unipolar/Bipolar Bit. Set by user to enable unipolar coding, that is, a zero differential input results in
0x0000(00) output, and a full-scale differential input results in 0xFFFF(FF) output. Cleared by the user to
enable bipolar coding. A negative full-scale differential input results in an output code of 0x0000(00), a
zero differential input results in an output code of 0x8000(00), and a positive full-scale differential input
results in an output code of 0xFFFF(FF).
This bit must be programmed with a Logic 0 for correct operation.
These bits must be programmed with a Logic 1 for correct operation.
These bits must be programmed with a Logic 0 for correct operation.
This bit must be programmed with a Logic 1 for correct operation.
This bit must be programmed with a Logic 0 for correct operation.
Channel Select bits. Written by the user to select the active analog input channel to the ADC.
CH2
0
0
0
0
1
1
1
1
CON11
0(0)
CON10
1(1)
CH1
0
0
1
1
0
0
1
1
CON9
1(1)
Rev. A | Page 14 of 24
CON8
1(1)
CH0
0
1
0
1
0
1
0
1
CON7
0(0)
CON6
0(0)
CON5
0(0)
Temp Sensor
Channel
AIN(+) − AIN(–)
Reserved
Reserved
AIN(–) − AIN(–)
Reserved
Reserved
AV
DD
Monitor
CON4
1(1)
CON3
0(0)
CON2
CH2(0)
CON1
CH1(0)
LSB
CON0
CH0(0)