AD7148 Analog Devices, AD7148 Datasheet - Page 32

• Manufacturer Part Number: AD7148
• Manufacturer: Analog Devices

Specifications of AD7148

• Resolution (bits): 16bit
• # Chan: 8
• Sample Rate: 250kSPS
• Interface: I²C/Ser 2-Wire,Ser
• Analog Input Type: SE-Uni
• Ain Range: ± 8 pF (Delta C)
• Adc Architecture: Sigma-Delta
• Pkg Type: CSP

AD7148
POWER-UP SEQUENCE
When the AD7148 is powered up, the following sequence is
recommended when initially developing the AD7148 and host
microprocessor serial interface:
1.
2.
3.
CONVERSION
INTERFACE
INTERRUPT
SUPPLY
POWER
SERIAL
AD7148
Address 0x002 = 0x3230 (depends on number of
conversion stages used)
STAGE
Turn on the power supplies to the AD7148.
Write to the Bank 2 registers at Address 0x080 through
Address 0x0BF. These registers are contiguous, so a
sequential register write sequence can be applied.
Note that the Bank 2 register values are unique for each
application. Register values come from characterization
of the sensor in the application and may be provided by
Analog Devices after the sensor board has been developed.
Write to the Bank 1 registers at Address 0x000 through
Address 0x007, as outlined in the following list.
Caution
At this time, Address 0x001 must remain set to Default
Value 0x0000 during this contiguous write operation.
Register values:
Address 0x000 = 0x0B2
Address 0x001 = 0x000
HOST
CONVERSION STAGES DISABLED
1
2
3
4
0
1
2
Figure 44. Recommended Start-Up Sequence
3
FIRST CONVERSION SEQUENCE
4
5
Rev. A | Page 32 of 56
6
7
8
9
10
11
4.
5.
6.
7.
0
5
1
Write to the Bank 1 register, Address 0x001 = 0x00FF;
depends on number of conversion stages used.
Read back the corresponding interrupt status register
at Address 0x008, Address 0x009, or Address 0x00A.
The address to be read back is determined by the
interrupt output configuration, as explained in the
Interrupt Output section.
Note that the specific registers required to be read back
depend on each application. For buttons, the interrupt
status registers are read back, while other sensors read
data back according to the requirements of the slider or
wheel algorithm. Analog Devices provides this informa-
tion after the sensor board has been developed.
Repeat Step 5 every time INT is asserted.
Address 0x003 = 0x0419
Address 0x004 = 0x0832
Address 0x005 = interrupt enable register; depends
on required interrupt behavior
Address 0x006 = interrupt enable register; depends
on required interrupt behavior
Address 0x007 = interrupt enable register; depends
on required interrupt behavior
2
SECOND CONVERSION
SEQUENCE
9
10
11
0
6
1
2
THIRD CONVERSION
SEQUENCE
9
10
11
0
6
1