Datasheet

LTC2495
23
2495fd
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 first 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 configuration is required, this data
can be written into the device and a STOP command will
initiate the next conversion (see Figure 9).
Figure 10. Synchronize Multiple LTC2495s with a Global Address Call
Synchronizing Multiple LTC2495s with a Global
Address Call
In applications where several LTC2495s (or other I
2
C delta-
sigma ADCs from Linear Technology Corporation) are used
on the same I
2
C bus, all converters can be synchronized
through the use of a global address call. Prior to issuing the
global address call, all converters must have completed a
conversion cycle. The master then issues a START, followed
by the global address 1110111, and a write request. All
converters will be selected and acknowledge the request.
The master then sends a write byte (optional) followed by
the STOP command. This will update the channel selection
(optional) converter configuration (optional) and simultane-
ously initiate a START of conversion for all delta-sigma ADCs
on the bus (see Figure 10). In order to synchronize multiple
converters without changing the channel or configuration,
a STOP may be issued after acknowledgement of the global
write command. Global read commands are not allowed
and the converters will NACK a global read request.
applications inForMation
Figure 8. Write, Read, START Conversion
Figure 9. Start a New Conversion Without Reading Old Conversion Result
7-BIT ADDRESS
CONVERSION CONVERSIONADDRESSSLEEP DATA OUTPUTDATA INPUT
7-BIT ADDRESSS RW ACK ACKWRITE Sr PREAD
2495 F08
7-BIT ADDRESS
CONVERSION CONVERSIONSLEEP DATA INPUT
S W ACK WRITE (OPTIONAL) P
2495 F09
GLOBAL ADDRESS
SCL
SDA
LTC2495 LTC2495 LTC2495…
ALL LTC2495s IN SLEEP CONVERSION OF ALL LTC2495s
DATA INPUT
S W ACK WRITE (OPTIONAL) P
2495 F10