MAX1239EEE-T Datasheet, PDF (16/22 Pages) Maxim Integrated Products – 2.7V to 3.6V and 4.5V to 5.5V, Low-Power, 4-/12-Channel, 2-Wire Serial, 12-Bit ADCs

2.7V to 3.6V and 4.5V to 5.5V, Low-Power,
4-/12-Channel, 2-Wire Serial, 12-Bit ADCs
MASTER TO SLAVE
SLAVE TO MASTER
A. SINGLE CONVERSION WITH INTERNAL CLOCK
1
7
11
S SLAVE ADDRESS R A CLOCK STRETCH
tACQ
tCONV
8
RESULT 4 MSBs A
8
RESULT 8 LSBs
11
A P or Sr
NUMBER OF BITS
B. SCAN MODE CONVERSIONS WITH INTERNAL CLOCK
1
7
11
S SLAVE ADDRESS R A
CLOCK STRETCH
tACQ1
tCONV1
tACQ2
tCONV2
8
1
8
1
CLOCK STRETCH RESULT 1 ( 4MSBs) A RESULT 1 (8 LSBs) A
tACQN
tCONVN
8
1
8
11
RESULT N (4MSBs) A RESULT N (8LSBs) A P or Sr
NUMBER OF BITS
Figure 10. Internal Clock Mode Read Cycles
(FIFO) sequence. If AIN_/REF is set to be a reference
input or output (SEL1 = 1, Table 6), AIN_/REF is exclud-
ed from a multichannel scan. The memory contents can
be read continuously. If reading continues past the
result stored in memory, the pointer wraps around and
point to the first result. Note that only the current con-
version results is read from memory. The device must
be addressed with a read command to obtain new con-
version results.
The internal clock mode’s clock stretching quiets the
SCL bus signal reducing the system noise during con-
version. Using the internal clock also frees the bus
master (typically a microcontroller) from the burden of
running the conversion clock, allowing it to perform
other tasks that do not need to use the bus.
External Clock
When configured for external clock mode (CLK = 1),
the MAX1236–MAX1239 use the SCL as the conversion
MASTER TO SLAVE
SLAVE TO MASTER
A. SINGLE CONVERSION WITH EXTERNAL CLOCK
1
7
11
8
1
8
S SLAVE ADDRESS R A RESULT (4 MSBs) A RESULT (8 LSBs)
11
A P OR Sr
t_ACQ
t_CONV
NUMBER OF BITS
B. SCAN MODE CONVERSIONS WITH EXTERNAL CLOCK
1
7
11
8
1
8
1
S _{SLAVE ADDRESS} R A _{RESULT 1 (4 MSBs)} A _{RESULT 2 (8 LSBs)} A
t_ACQ1
t_CONV1
t_ACQ2
Figure 11. External Clock Mode Read Cycle
8
1
8
11
RESULT N (4 MSBs) ^A RESULT N (8 LSBs) A ^{P OR Sr}
t_ACQN
t_CONVN
NUMBER OF BITS
16 ______________________________________________________________________________________