
MAX1236–MAX1239
(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
2.7V to 3.6V and 4.5V to 5.5V, Low-Power,
4-/12-Channel, 2-Wire Serial, 12-Bit ADCs
16
______________________________________________________________________________________
B. SCAN MODE CONVERSIONS WITH INTERNAL CLOCK
S
1
SLAVE ADDRESS
A
71 1
R
CLOCK STRETCH
NUMBER OF BITS
P or Sr
1
8
RESULT 8 LSBs
8
RESULT 4 MSBs
A
1
A. SINGLE CONVERSION WITH INTERNAL CLOCK
S
1
SLAVE ADDRESS
71 1
R
CLOCK STRETCH
A
NUMBER OF BITS
P or Sr
1
8
RESULT 1 ( 4MSBs)
A
1
A
8
RESULT 1 (8 LSBs) A
8
RESULT N (8LSBs)
A
1
8
RESULT N (4MSBs)
SLAVE TO MASTER
MASTER TO SLAVE
CLOCK STRETCH
tACQ1
tCONV2
tACQ2
tCONVN
tACQN
tCONV
tACQ
1
tCONV1
Figure 10. Internal Clock Mode Read Cycles
SLAVE ADDRESS
tCONV1
tACQ1
tACQ2
tCONVN
tACQN
tCONV
tACQ
NUMBER OF BITS
1
8
A
1
S
1
A
71 1
R
S
1
71 1
R
P OR Sr
1
8
A
1
A
8
A
8
B. SCAN MODE CONVERSIONS WITH EXTERNAL CLOCK
1
SLAVE ADDRESS
P OR Sr
RESULT (8 LSBs)
8
A
1
RESULT (4 MSBs)
A. SINGLE CONVERSION WITH EXTERNAL CLOCK
SLAVE TO MASTER
MASTER TO SLAVE
RESULT 1 (4 MSBs)
RESULT 2 (8 LSBs)
RESULT N (8 LSBs)
A
1
8
RESULT N (4 MSBs)
A
Figure 11. External Clock Mode Read Cycle