Datasheet

LTC2489
14
2489fa
Operation Sequence
The LTC2489 acts as a transmitter or receiver, as shown
in Figure 4. The device may be programmed to select
an input channel, differential or single-ended mode, and
channel polarity.
Table 4. Address Assignment
CA1 CA0 ADDRESS
LOW LOW 0010100
LOW HIGH 0010110
LOW FLOAT 0010101
HIGH LOW 0100110
HIGH HIGH 0110100
HIGH FLOAT 0100111
FLOAT LOW 0010111
FLOAT HIGH 0100101
FLOAT FLOAT 0100100
Continuous Read
In applications where the input channel does not need to
change for each cycle, the conversion can be continuously
performed and read without a write cycle (see Figure 5).
The input channel remains unchanged from the last value
written into the device. If the device has not been writ-
ten to since power up, the channel selection is set to the
default value of CH0 = IN
+
, CH1 = IN
. At the end of a read
operation, a new conversion automatically begins. At the
conclusion of the conversion cycle, the next result may
be read using the method described above. If the conver-
sion cycle is not concluded and a valid address selects
the device, the LTC2489 generates a NAK signal indicating
the conversion cycle is in progress.
Continuous Read/Write
Once the conversion cycle is concluded, the LTC2489 can
be written to and then read from using the Repeated Start
(Sr) command.
APPLICATIONS INFORMATION
Figure 4. Conversion Sequence
Figure 5. Consecutive Reading with the Same Input/Configuration
S ACK DATA Sr DATA TRANSFERRING P
7-BIT ADDRESS
R/W
2489 F04
CONVERSION CONVERSIONSLEEP DATA INPUT/OUTPUT
7-BIT ADDRESS 7-BIT ADDRESSSSRRACK ACKREAD READPP
2489 F05
CONVERSION CONVERSIONCONVERSIONSLEEP DATA OUTPUTDATA INPUT SLEEP