Datasheet

LTC2487
20
2487fd
Figure 6. Conversion Sequence
Figure 7. Consecutive Reading with the Same Input/Confi guration
Table 6. 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
APPLICATIONS INFORMATION
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
conversion cycle is not concluded and a valid address
selects the device, the LTC2487 generates a NAK signal
indicating the conversion cycle is in progress.
Continuous Read/Write
Once the conversion cycle is concluded, the LTC2487 can
be written to and then read from using the Repeated Start
(Sr) command.
Figure 8 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
24 bits are read out of the device or after a Stop command.
The following conversion will be performed using the newly
programmed data. In cases where the same speed (1x/2x
mode), rejection frequency (50Hz, 60Hz, 50Hz and 60Hz)
and gain is used but the channel is changed, a Stop or
Repeated Start may be issued after the fi rst byte (channel
selection data) is written into the device.
Discarding a Conversion Result and Initiating a New
Conversion with Optional Write
At the conclusion of a conversion cycle, a write cycle
can be initiated. Once the write cycle is acknowledged, a
Stop command will start a new conversion. If a new input
channel or conversion confi guration is required, this data
S ACK DATA Sr DATA TRANSFERRING P
7-BIT ADDRESS
R/W
2487 F06
CONVERSION CONVERSIONSLEEP DATA INPUT/OUTPUT
7-BIT ADDRESS 7-BIT ADDRESSSSRRACK ACKREAD READPP
2487 F07
CONVERSION CONVERSIONADDRESSSLEEP DATA OUTPUTDATA INPUT SLEEP
Operation Sequence
The LTC2487 acts as a transmitter or receiver, as shown
in Figure 6. The device may be programmed to perform
several functions. These include input channel selection,
measure the internal temperature, selecting the line fre-
quency rejection (50Hz, 60Hz, or simultaneous 50Hz and
60Hz), a 2x speed mode and gain.
Continuous Read
In applications where the input channel/confi guration does
not need to change for each cycle, the conversion can be
continuously performed and read without a write cycle
(see Figure 7). The confi guration/input channel remains
unchanged from the last value written into the device. If
the device has not been written to since power up, the
confi guration is set to the default value. At the end of a