MAX1204_12 Datasheet, PDF (17/23 Pages) Maxim Integrated Products – 5V, 8-Channel, Serial, 10-Bit ADC with 3V Digital Interface

MAX1204
5V, 8-Channel, Serial, 10-Bit ADC
with 3V Digital Interface
CLOCK
MODE
SHDN
DIN
INTERNAL
SETS EXTERNAL
CLOCK MODE
SXXXXX11
EXTERNAL
SX X XXX0 1
SETS FAST
POWER-DOWN
MODE
SETS EXTERNAL
CLOCK MODE
S XX XXX1 1
DOUT
DATA VALID
(10 + 2 DATA BITS)
DATA VALID
(10 + 2 DATA BITS)
MODE
POWERED UP
Figure 12a. Timing Diagram for Power-Down Modes (External Clock)
POWERED UP
FAST
POWER-DOWN
EXTERNAL
DATA
INVALID
FULL
POWER-
DOWN
POWERED
UP
CLOCK
MODE
SETS INTERNAL
CLOCK MODE
INTERNAL CLOCK MODE
SETS FULL
POWER-DOWN
DIN
SXXXXX10
SXXXXX0 0
S
DOUT
DATA VALID
DATA VALID
SSTRB
MODE
CONVERSION
POWERED UP
CONVERSION
FULL
POWER-DOWN
POWERED
UP
Figure 12b. Timing Diagram for Power-Down Modes (Internal Clock)
Hardware Power-Down
The SHDN pin places the converter into full
power-down mode. Unlike the software power-down
modes, conversion is not completed; it stops coinci-
dentally with SHDN being brought low. There is no
power-up delay if an external reference, which is not
shut down, is used. SHDN also selects internal or
external reference compensation (Table 7).
Power-Down Sequencing
The MAX1204’s automatic power-down modes can
save considerable power when operating at less than
maximum sample rates. The following sections discuss
the various power-down sequences.
Lowest Power at up to
500 Conversions per Channel per Second
Figure 14a depicts MAX1204’s power consumption for one
or eight channel conversions using full power-down mode
and internal reference compensation. A 0.01µF bypass
capacitor at REFADJ forms an RC filter with the internal
20kΩ reference resistor, with a 0.2ms time constant. To
achieve full 10-bit accuracy, 10 time constants (or 2ms in
this example) are required for the reference buffer to settle.
When exiting FULLPD, waiting this 2ms in FASTPD mode
(instead of just exiting FULLPD mode and returning to nor-
mal operating mode) reduces power consumption by a
factor of 10 or more (Figure 13).
Maxim Integrated
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