Datasheet
AD7993/AD7994
Rev. 0 | Page 30 of 32
911A9
S
WA A
Sr RA A
SECOND DATA BYTE
(LSBs)
FIRST DATA BYTE
(MSBs)
COMMAND/ADDRESS
POINT BYTE
7-BIT ADDRESS
7-BIT ADDRESS
SDA
119
SCL
SDA
SCL
9 9
Sr/P
8
ACK BY
AD7993/AD7994
ACK BY
AD7993/AD7994
ACK BY
MASTER
NACK BY
MASTER
ACK BY
AD7993/AD7994
03472-0-033
A
Figure 33. Mode 2 Operation
911
SCL
9
S
7-BIT ADDRESS
WA
COMMAND/ADDRESS
POINT BYTE
A
S
D
A
FIRST DATA BYTE
(MSBs)
A
SECOND DATA BYTE
(LSBs)
FIRST DATA BYTE
(MSBs)
SECOND DATA BYTE
(LSBs)
A
Sr 7-BIT ADDRESS
RA
SDA
9
9
1
1
SCL
9
8
ACK BY
AD7993/AD7994
ACK BY
AD7993/AD7994
ACK BY
MASTER
ACK BY
MASTER
ACK BY
MASTER
ACK BY
AD7993/AD7994
A
9
9
RESULT FROM CH1
RESULT FROM CH2
A/A
03472-0-034
Figure 34. Mode 2 Sequence Operation
MODE 3—AUTOMATIC CYCLE INTERVAL MODE
An automatic conversion cycle can be selected and enabled by
writing a value to the cycle timer register. A conversion cycle
interval can be set up on the AD7993/AD7994 by programming
the relevant bits in the 8-bit cycle timer register, as decoded in
Table 25. Only the 3 LSB are used; the 5 MSB should contain 0s.
When the 3 LSB of the register are programmed with any
configuration other than all 0s, a conversion takes place every
X ms; the cycle interval, X, depends on the configuration of
these three bits in the cycle timer register. There are seven
different cycle time intervals to choose from, as shown in
Table 25. Once the conversion takes place, the part powers
down again until the next conversion. To exit this mode of
operation, the user must program the 3 LSB of the cycle timer
register to contain all 0s. To select a channel(s) for operation in
the cycle mode, set the corresponding channel bit(s), D7 to D4,
of the configuration register. If more than one channel bit is set
in the configuration register, the ADC automatically cycles
through the channel sequence starting with the lowest channel
and working its way up through the sequence. Once the
sequence is complete, the ADC starts converting on the lowest
channel again, continuing to loop through the sequence until
the cycle timer register’s contents are set to all 0s. This mode
is useful for monitoring signals such as battery voltage, and
temperature, alerting only when the limits are violated.