LTC2485 LINER [Linear Technology], LTC2485 Datasheet - Page 17

• Manufacturer Part Number: LTC2485
• Description: 24-Bit ?? ADC with Easy Drive Input Current Cancellation and I2C Interface
• Manufacturer: LINER [Linear Technology]

APPLICATIO S I FOR ATIO
OPERATION SEQUENCE
The LTC2485 acts as a transmitter or receiver. The device
may be programmed to perform several functions. These
include measuring an external differential input signal or
an integrated temperature sensor, selecting line frequency
rejection (50Hz, 60Hz, or simultaneous 50Hz and 60Hz),
and a 2x speed up mode.
Continuous Read
In applications where the configuration does not need to
change for each conversion cycle, the conversion result
can be continuously read. The configuration remains
unchanged from the last value written into the device. If
the device has not been written to since power up, the
configuration is set to the default value (Input External,
simultaneous 50Hz/60Hz rejection, and 1x speed mode).
The operation sequence is shown in Figure 6. When the
conversion is finished, the device may be addressed for
CONVERSION
S
S
7-BIT ADDRESS
CONVERSION
S
CONVERSION
7-BIT ADDRESS
7-BIT ADDRESS
U
SLEEP
U
R
SLEEP
ACK
SLEEP
DATA OUTPUT
W ACK
Figure 6. Consecutive Reading at the Same Configuration
W
READ
R/W
DATA INPUT
Figure 5. The LTC2485 Conversion Sequence
Figure 7. Write, Read, Start Conversion
WRITE
ACK
U
P
Sr
DATA
CONVERSION
7-BIT ADDRESS
a read operation. At the end of a read operation, a new
conversion begins. At the conclusion of the conversion
cycle, the next result may be read using the method
described above. If the conversion cycle is not con-
cluded and a valid address selects the device, the LTC2485
generates a NAK signal indicating the conversion cycle
is in progress.
Continuous Read/Write
Once the conversion cycle is concluded, the LTC2485 can
be written to then read from, using the repeated Start
(Sr) command.
Figure 7 shows a cycle which begins with a data Write, a
repeated start, followed by a read, and concluded with a
stop command. The following conversion begins after all
32 bits are read out of the device or after the STOP
command and uses the newly programmed configura-
tion data.
DATA INPUT/OUTPUT
ADDRESS
S
Sr
7-BIT ADDRESS
DATA TRANSFERRING
R
ACK
SLEEP
DATA OUTPUT
R
READ
ACK
DATA OUTPUT
READ
CONVERSION
P
P
CONVERSION
LTC2485
2485 F07
CONVERSION
P
17
2485 F05
2485fa
2485 F06