AD7291_11 AD [Analog Devices], AD7291_11 Datasheet - Page 15

• Manufacturer Part Number: AD7291_11
• Description: 8-Channel, I2C, 12-Bit SAR ADC with Temperature Sensor
• Manufacturer: AD [Analog Devices]

INTERNAL REGISTER STRUCTURE
The AD7291 contains 34 internal registers (see Figure 23) that
are used to store conversion results, high and low conversion
limits, and information to configure and control the device.
There are 33 data registers and one address pointer register.
Each data register has an address that the address pointer
register points to when communicating with it. Table 9 details
which registers are read, write, or read/write.
ADDRESS POINTER REGISTER
The address pointer register is the register to which the first
data byte of every write operation is written automatically;
therefore, this register does not have and does not require an
address. The address pointer register is an 8-bit register in
which the six LSBs are used as pointer bits to store an address
that points to one of the AD7291’s data registers. The first byte
following each write address is to the address pointer register,
containing the address of one of the data registers. The six LSBs
select the data register to which subsequent data bytes are
written. Only the six LSBs of this register are used to select a
data register. During power-up, the address pointer register
contains all 0s, pointing to the command register.
Table 8. Address Pointer Register
D1
0
D0
0
P5
P4
Register select
P3
P2
P1
P0
Rev. 0 | Page 15 of 28
REGISTER
ADDRESS
POINTER
Figure 23. AD7291 Register Structure
SERIAL BUS INTERFACE
T
RESULT REGISTER
RESULT REGISTER
RESULT REGISTER
SENSE
CH0 HYSTERESIS
CH7 HYSTERESIS
CH1 HYSTERESIS
T
T
VOLTAGE CONV
ALERT STATUS
ALERT STATUS
CH0 DATA
CH1 DATA
CH7 DATA
SENSE
SENSE
CH0 DATA
CH1 DATA
CH7 DATA
T
REGISTER A
REGISTER B
T
SENSE
COMMAND
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
SENSE
HYSTERESIS
DATA
DATA
CONV
AVG
HIGH
LOW
HIGH
LOW
HIGH
LOW
HIGH
LOW
AD7291
SDA
SCL