AD7709 Analog Devices, AD7709 Datasheet - Page 17

• Manufacturer Part Number: AD7709
• Description: 16-Bit Sigma Delta ADC with Current Sources, Switchable Reference Inputs and I/O Port
• Manufacturer: Analog Devices

Specifications of AD7709

• Resolution (bits): 16bit
• # Chan: 4
• Sample Rate: n/a
• Interface: Ser,SPI
• Analog Input Type: Diff-Uni,SE-Uni
• Ain Range: (2Vref/PGA Gain) p-p
• Adc Architecture: Sigma-Delta
• Pkg Type: SOP

Bit
Location
CONFIG16
CONFIG15
CONFIG14
CONFIG13
CONFIG12
CONFIG11
CONFIG10
CONFIG9
CONFIG8
CONFIG7
CONFIG6
CONFIG5
CONFIG4
REV. A
Bit
Name
I1EN0
P4DIG
P3DIG
P2EN
P1EN
P4DAT
P3DAT
P2DAT
P1DAT
REFSEL
CH2
CH1
CH0
Description
IEXC1 Current Source Enable Bit
Digital Input Enable.
Set by user to enable pin AIN4/P4 as a digital input. A weak pull-up resistor is activated in this state.
Cleared by user to configure pin AIN4/P4 as an analog input.
Digital Input Enable.
Set by user to enable pin AIN3/P3 as a digital input. A weak pull-up resistor is activated in this state.
Cleared by user to configure pin AIN3/P3 as an analog input.
SW2/P2 Digital Output Enable Bit.
Set by user to enable P2 as a regular digital output pin.
Cleared by user to three-state the P2 output. PSW2 takes precedence over P2EN.
SW1/P1 Digital Output Enable Bit.
Set by user to enable P1 as a regular digital output pin.
Cleared by user to three-state the P1 output. PSW1 takes precedence over P1EN.
Digital Input Port Data Bit.
P4DAT is read only and will return a zero if P4DIG equals zero.
If P4 is enabled as a digital input, the readback value indicates the status of pin P4.
Digital Input Port Data Bit.
P3DAT is read only and will return a zero if P3DIG equals zero.
If P3 is enabled as a digital input, the readback value indicates the status of pin P3.
Digital Output Port Data Bit. P2 is a digital output only. When the port is active as an output (P2EN = 1),
the value written to this data bit appears at the output port. Reading P2DAT will return the last value
written to the P2DAT bit.
Digital Output Port Data Bit. P1 is a digital output only. When the port is active as an output (P1EN = 1),
the value written to this data bit appears at the output port. Reading P1DAT will return the last value
written to the P1DAT bit.
ADC Reference Input Select.
Cleared by the user to select REFIN1(+) and REFIN1(–) as the ADC reference.
Set by the user to select REFIN2(+) and REFIN2(–) as the ADC reference.
ADC Input Channel Selection Bit. It is used in conjunction with CH1 and CH0 as shown below.
ADC Input Channel Selection Bit. It is used in conjunction with CH2 and CH0 as shown below.
ADC Input Channel Selection Bit. It is used in conjunction with CH2 and CH1 as shown below.
CH2 CH1 CH0 Positive Input
0
0
0
0
1
1
1
1
I1EN1
0
0
1
1
The Buffer column indicates if the analog inputs are buffered or unbuffered. This determines the common-mode input range
on each input. If the input is unbuffered (AINCOM), the common-mode input includes ground.
Table VII. Configuration Register Bit Designations (continued)
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
I1EN0
0
1
0
1
AIN1
AIN2
AIN3
AIN4
AIN1
AIN3
AINCOM
AIN2
Function
IEXC1 Current Source OFF
IEXC1 Current Source Routed to the IOUT1 Pin
IEXC1 Current Source Routed to the IOUT2 Pin
Reserved
–17–
Negative Input Buffer
AINCOM
AINCOM
AINCOM
AINCOM
AIN2
AIN4
AINCOM
AIN2
Positive Analog Input
Positive Analog Input
Positive Analog Input
Positive Analog Input
Positive and Negative Analog Inputs
Positive and Negative Analog Inputs
None
Positive and Negative Analog Inputs
AD7709