AD7993 Analog Devices, AD7993 Datasheet - Page 30

• Manufacturer Part Number: AD7993
• Description: 4-Channel, 10-Bit ADC with I2C Compatible Interface in 16-Lead TSSOP
• Manufacturer: Analog Devices

Specifications of AD7993

• Resolution (bits): 10bit
• # Chan: 4
• Sample Rate: 188kSPS
• Interface: I²C/Ser 2-Wire,Ser
• Analog Input Type: SE-Uni
• Ain Range: Uni (Vref)
• Adc Architecture: SAR
• Pkg Type: SOP

AD7993/AD7994
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
SCL
SDA
SDA
SCL
SDA
SDA
SCL
SCL
Sr
S
1
1
7-BIT ADDRESS
7-BIT ADDRESS
Sr
S
1
1
AD7993/AD7994
AD7993/AD7994
W A
8
R A
ACK BY
ACK BY
7-BIT ADDRESS
7-BIT ADDRESS
9
9
1
1
COMMAND/ADDRESS
FIRST DATA BYTE
POINT BYTE
(MSBs)
AD7993/AD7994
AD7993/AD7994
ACK BY
W
8
R
Figure 34. Mode 2 Sequence Operation
AD7993/AD7994
ACK BY
A
A
9
MASTER
9
RESULT FROM CH1
ACK BY
ACK BY
Figure 33. Mode 2 Operation
A
A
1
1
9
9
Rev. 0 | Page 30 of 32
COMMAND/ADDRESS
SECOND DATA BYTE
FIRST DATA BYTE
POINT BYTE
(LSBs)
(MSBs)
A
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.
MASTER
ACK BY
AD7993/AD7994
A
9
MASTER
ACK BY
ACK BY
9
A
A
9
FIRST DATA BYTE
(MSBs)
SECOND DATA BYTE
(LSBs)
RESULT FROM CH2
MASTER
ACK BY
A
9
SECOND DATA BYTE
NACK BY
MASTER
(LSBs)
A
9
Sr/P
A/A
9